DOCSLIB.ORG

Molecular Biology

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Molecular Biology Molecular biology 1. Cytoskeleton 2. Motor proteins 3. Signal sequences-navigated protein transport 4. Apoptosis 5. RNA: structure and function 6. RNAinterference 7. Control of gene expression 8. Cojugative gene transfer 9. DNA damage response 10. Cell –cell signaling 11. Bacterial chemotaxis 12. Bacterial cell motility 13. Bacterial toxins 14. Viroids Vladimír Jirků 1. Cytoskeleton The Cytoskeleton is a highly dynamic (complex, responsive) filamentous structure, acting as an intracellular scaffolding organizing the cell's contents to maximize inner-cell differentiation, transport and coordination of cell processes, as well as maintaining or altering cell shape and cell motion. In addition, interactions with the cytoskeleton influence a number of other behaviors, including signaling pathways (But one of the most important roles of the microtubule cytoskeleton is that it regulates and thus coordinates actin polymerization. Without this coordination, cells can't maintain their ability to have front ends and back ends – this front / back dichotomy is referred to as “cell polarity”). It is contained in all eukaryotic cells. While the cytoskeleton is an interconnected network, it is conventionally broken into three distinct cytoplasmic systems: microtubules, actin filaments ( microfilaments) and intermediate filaments. Microtubules: They are hollow filaments of about 25 nm, formed by 13 protofilaments which, in turn, are polymers of alpha and beta tubulin. They have a very dynamic behaviour, binding GTP for polymerization. They are organized by the microtubule organizing centre (MTOC, centrosome , - spindle pole body in yeast cell). They play key roles in: intracellular transport (associated with motor proteins) - transport cell compartments; the axoneme of cilia and flagella; the mitotic spindle; synthesis of the cell wall in plant cell, among others. Microtubules have + end / - end (MTOC) polarity. Actin filaments These filaments (around 7 nm in diameter) are composed of two actin chains oriented in an helicoidal shape. They are mostly concentrated just beneath the plasma membrane, as they keep cellular shape, form cytoplasmatic protuberances (like pseudopodia and microvili), and participate in some cell-to-cell or cell-to-matrix junctions and in the transduction of signals. They are also important for cytokinesis and, along with myosin, muscular contraction. G- actin (globular actin) with bound ATP can polymerize, to form F-actin (filamentous actin). F-actin may hydrolyze its bound ATP to ADP + Pi and release Pi. ADP release from the filament does not occur because the cleft opening is blocked. ADP/ATP exchange: G-actin can release ADP and bind ATP, which is usually present in the cytosol at higher concentration than ADP. Actin filaments have polarity. The actin monomers all orient with their cleft toward the same end of the filament (designated the minus end). Actin monomers spiral around the axis of the filament, with a structure resembling a double helix. At the ends of actin filaments are boud capping proteins. Different capping proteins may either stabilize an actin filament or promote disassembly. They may have a role in determining filament length. Cross-linking proteins organize actin filaments into bundles or networks. Actin- binding domains of several of the cross-linking proteins (e.g., filamin, -actinin, spectrin, dystrophin and fimbrin) are homologous. Most cross-linking proteins are dimeric or have 2 actin-binding domains. Some actin-binding proteins such as -actinin, villin and fimbrin bind actin filaments into parallel bundles. Depending on the length of a cross-linking protein, or the distance between actin-binding domains, actin filaments in parallel bundles may be held close together, or may be far enough apart to allow interaction with other proteins such as myosin. Filamins dimerize, through antiparallel association of their C-terminal domains, to form V-shaped cross-linking proteins that have a flexible shape due to hinge regions. Filamins organize actin filaments into loose networks that give some areas of the cytosol a gel-like consistency. Filamins may also have scaffolding roles relating to their ability to bind constituents of signal pathways such as plasma membrane receptors, calmodulin, caveolin, protein kinase C, transcription factors, etc. Nucleation. three 'barbed'-end nucleators of F actin have been described. The ARP2/3 complex, made up of two ARP proteins and five associated subunits (ARPC1–5/p41–16), serves as a template for F-actin formation and can also interact with the sides of existing actin filaments, forming branched F-actin arrays. Upstream regulation: cofilins are inhibited in their activity and dynamics by specific kinases (such as LIM (Lin-11/Isl-1/Mec-3) or TES kinases) that phosphorylate the proteins on the conserved serine residue. Dephosphorylation by phosphatases activates cofilins. ARP, actin-related protein; CAP, cyclase-associated protein; FH1, formin homology 1; FH2, formin homology Filopodia (also called microspikes) are long, thin and transient processes that extend out from the cell surface. Bundles of parallel actin filaments, with their plus ends oriented toward the filopodial tip, are cross-linked within filopodia by a small actin-binding protein such as fascin. The closely spaced actin filaments provide stiffness. Microvilli are shorter / more numerous protrusions of the cell surface found in some cells. Tightly bundled actin filaments within these structures also have their plus ends oriented toward the tip. Small cross-linking proteins such as fimbrin and villin bind actin filaments together within microvilli. Lamellipodia are thin but broad projections at the edge of a mobile cell. Lamellipodia are dynamic structures, constantly changing shape. Lamellipodia, at least in some motile cells, have been shown to contain extensively branched arrays of actin filaments, oriented with their plus (barbed) ends toward the plasma membrane. Forward extension of a lamellipodium occurs by growth of actin filaments adjacent to the plasma membrane. Cells move through the rapid rearrangement of the actin cytoskeleton. In the dendritic nucleation model, several signaling pathways converge to activate WASp/Scar proteins, which in turn activate the Arp2/3 complex. Active Arp2/3 complex binds to the side of an existing filament and nucleates new filament growth towards the cell membrane. The combined force from many growing filaments pushes the cell membrane forward, moving the cell.. ARP, actin-related protein; CAP, cyclase-associated protein; FH1, formin homology 1; FH2, formin homology Intermediate filaments These filaments, 8 to 11 nanometers in diameter, are strongly bound and very heterogeneous constituents of the cytoskeleton. They organize the internal tridimensional structure of the cell (they are structural support of the nuclear membrane for example). They also participate in some cell-cell and cell-matrix junctions. Respectively, they are made from many different types of proteins (desmin, vimentin, keratin, lamin…….). Intermediate filaments are essential for normal tissue structure and function; they provide physical resilience for cells to withstand the mechanical stresses of the tissue in which they are expressed. They are found in the nucleus (lamins) and the cytoplasm (cytoplasmic intermediate filaments). Assembly: Intermediate filaments are assembled from tetramers: two monomers form a parallel dimer by the winding of their α-helical rods into a coiled coil, oriented in register and in the same direction, and then two dimers join side-by-side in a staggered anti-parallel orientation to form a bidirectional tetramer. Each dimer is 48 nm long; because the dimers are staggered the tetramer is somewhat longer. The anti-parallel orientation of tetramers means that, unlike microtubules and microfilaments (which have a preferred assembly end), intermediate filaments do not show polarized unidirectional properties. Assembly and disassembly is regulated by cycles of phosphorylation and dephosphorylation; polymerization of intermediate filaments occurs rapidly and does not require cofactors or associated proteins. In most cells, intermediate filaments assemble into complex networks that course through the cytoplasm between the nucleus and the cell surface. Towards the cell center, they are attached to the nuclear envelope, and in the region of the plasma membrane, they are associated with various adhesion structures such as the desmosomes and hemidesmosomes of epithelial cells and the focal adhesions of fibroblasts. Cytoskeletal intermediate filaments play important roles in a wide range of cellular functions. These include the formation and maintenance of cell shape, cellular mechanical integrity, signal transduction, and the overall stability and integration of other cytoskeletal systems, i.e. microtubules and actin filaments. Types of intermediate filaments: The proteins comprising these filasments are encoded by approximately 70 different genes. This large family of proteins is subdivided into five types, four of which are located in the cytoplasm (cytoskeletal IF) and one in the nucleus (nucleoskeletal IF). In the cytoplasm, one, two or even more types of IF protein chains can polymerize into cytoskeletal IF of 10 nm diameter. Textbooks describe IF as very stable and rigid structures, only recognized for their maintenance of the mechanical stability of cells. However, the results of live cell imaging studies demonstrate the opposite. These studies have shown that
Load more

Recommended publications
  • Cytoskeleton and Cell Motility
    Cytoskeleton and Cell Motility Thomas Risler1 1Laboratoire Physicochimie Curie (CNRS-UMR 168), Institut Curie, Section de Recherche, 26 rue d’Ulm, 75248 Paris Cedex 05, France (Dated: January 23, 2008) PACS numbers: 1 Article Outline Glossary I. Definition of the Subject and Its Importance II. Introduction III. The Diversity of Cell Motility A. Swimming B. Crawling C. Extensions of cell motility IV. The Cell Cytoskeleton A. Biopolymers B. Molecular motors C. Motor families D. Other cytoskeleton-associated proteins E. Cell anchoring and regulatory pathways F. The prokaryotic cytoskeleton V. Filament-Driven Motility A. Microtubule growth and catastrophes B. Actin gels C. Modeling polymerization forces D. A model system for studying actin-based motility: The bacterium Listeria mono- cytogenes E. Another example of filament-driven amoeboid motility: The nematode sperm cell VI. Motor-Driven Motility A. Generic considerations 2 B. Phenomenological description close to thermodynamic equilibrium C. Hopping and transport models D. The two-state model E. Coupled motors and spontaneous oscillations F. Axonemal beating VII. Putting It Together: Active Polymer Solutions A. Mesoscopic approaches B. Microscopic approaches C. Macroscopic phenomenological approaches: The active gels D. Comparisons of the different approaches to describing active polymer solutions VIII. Extensions and Future Directions Acknowledgments Bibliography Glossary Cell Structural and functional elementary unit of all life forms. The cell is the smallest unit that can be characterized as living. Eukaryotic cell Cell that possesses a nucleus, a small membrane-bounded compartment that contains the genetic material of the cell. Cells that lack a nucleus are called prokaryotic cells or prokaryotes. Domains of life archaea, bacteria and eukarya - or in English eukaryotes, and made of eukaryotic cells - which constitute the three fundamental branches in which all life forms are classified.
    [Show full text]
  • Genscript Product Catalog 2010-2011
    GenScript Product Catalog 2010-2011 GenScript Product Catalog GenScript USA Inc. 120 Centennial Ave. Piscataway, NJ 08854 USA Tel: 1-732-885-9188 / 1-732-885-9688 Toll-Free Tel: 1-877-436-7274 Fax: 1-732-210-0262 / 1-732-885-5878 Email: [email protected] Business Development Tel: 1-732-317-5088 Email: [email protected] 2010-2011 GenScript GenScript The Biology CRO The Biology CRO Date Version: 04/21/2010 Your Innovation Partner in Drug Discovery! Welcome to GenScript GenScript USA Incorporation, founded in 2002, is a fast growing biotechnology company and contract research organization (CRO) specialized in custom services and consumable products for academic and pharmaceutical research. Built on our assembly-line mode, one-stop solution, continuous improvement, and stringent IP protection, GenScript provides a comprehensive portfolio of products and services at the most competitive prices in the industry to meet your research needs every day. Over the years, GenScript’s scientists have developed many innovative technologies that allow us to maintain the position at the cutting edge of biological and medical research while offering cost-effective solutions for customers to accelerate their research. Our advanced expertise includes proprietary technology for custom gene synthesis, OptimumGeneTM codon optimization technology, CloneEZ® seamless cloning technology, FlexPeptideTM technology for custom peptide synthesis, BacPowerTM technology for protein expression and purification, T-MaxTM adjuvant and advanced nanotechnology for custom antibody production, as well as ONE-HOUR WesternTM detection system and eStainTM protein staining system. GenScript offers a broad range of reagents, optimized kits, and system solutions to help you unravel the mysteries of biology.
    [Show full text]
  • NIH Public Access Author Manuscript Cell Signal
    NIH Public Access Author Manuscript Cell Signal. Author manuscript; available in PMC 2012 December 1. NIH-PA Author ManuscriptPublished NIH-PA Author Manuscript in final edited NIH-PA Author Manuscript form as: Cell Signal. 2011 December ; 23(12): 1907±1920. doi:10.1016/j.cellsig.2011.07.023. Management of cytoskeleton architecture by molecular chaperones and immunophilins Héctor R. Quintáa, Natalia M. Galignianaa, Alejandra G. Erlejmanb, Mariana Lagadaria, Graciela Piwien Pilipuka, and Mario D. Galignianaa,b,* aInstituto de Biología y Medicina Experimental-CONICET, Vuelta de Obligado 2490, Buenos Aires (C1428ADN), Argentina. bDepartamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Universidad de Buenos Aires, Buenos Aires (C1428EGA), Argentina. Abstract Cytoskeletal structure is continually remodeled to accommodate normal cell growth and to respond to pathophysiological cues. As a consequence, several cytoskeleton-interacting proteins become involved in a variety of cellular processes such as cell growth and division, cell movement, vesicle transportation, cellular organelle location and function, localization and distribution of membrane receptors, and cell-cell communication. Molecular chaperones and immunophilins are counted among the most important proteins that interact closely with the cytoskeleton network, in particular with microtubules and microtubule-associated factors. In several situations, heat-shock proteins and immunophilins work together as a functionally active heterocomplex,
    [Show full text]
  • Arxiv:1105.2423V1 [Physics.Bio-Ph] 12 May 2011 C
    Cytoskeleton and Cell Motility Thomas Risler Institut Curie, Centre de Recherche, UMR 168 (UPMC Univ Paris 06, CNRS), 26 rue d'Ulm, F-75005 Paris, France Article Outline C. Macroscopic phenomenological approaches: The active gels Glossary D. Comparisons of the different approaches to de- scribing active polymer solutions I. Definition of the Subject and Its Importance VIII. Extensions and Future Directions II. Introduction Acknowledgments III. The Diversity of Cell Motility Bibliography A. Swimming B. Crawling C. Extensions of cell motility IV. The Cell Cytoskeleton A. Biopolymers B. Molecular motors C. Motor families D. Other cytoskeleton-associated proteins E. Cell anchoring and regulatory pathways F. The prokaryotic cytoskeleton V. Filament-Driven Motility A. Microtubule growth and catastrophes B. Actin gels C. Modeling polymerization forces D. A model system for studying actin-based motil- ity: The bacterium Listeria monocytogenes E. Another example of filament-driven amoeboid motility: The nematode sperm cell VI. Motor-Driven Motility A. Generic considerations B. Phenomenological description close to thermo- dynamic equilibrium arXiv:1105.2423v1 [physics.bio-ph] 12 May 2011 C. Hopping and transport models D. The two-state model E. Coupled motors and spontaneous oscillations F. Axonemal beating VII. Putting It Together: Active Polymer Solu- tions A. Mesoscopic approaches B. Microscopic approaches 2 Glossary I. DEFINITION OF THE SUBJECT AND ITS IMPORTANCE Cell Structural and functional elementary unit of all life forms. The cell is the smallest unit that can be We, as human beings, are made of a collection of cells, characterized as living. which are most commonly considered as the elementary building blocks of all living forms on earth [1].
    [Show full text]
  • Cytoskeleton and Cell Motility Thomas Risler
    Cytoskeleton and Cell Motility Thomas Risler To cite this version: Thomas Risler. Cytoskeleton and Cell Motility. Robert A. Meyers. Encyclopedia of Complexity and System Science, Springer, pp.1738-1774, 2009, 978-0-387-75888-6. 10.1007/978-0-387-30440-3_112. hal-00961037 HAL Id: hal-00961037 https://hal.archives-ouvertes.fr/hal-00961037 Submitted on 22 Mar 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Cytoskeleton and Cell Motility Thomas Risler Institut Curie, Centre de Recherche, UMR 168 (UPMC Univ Paris 06, CNRS), 26 rue d'Ulm, F-75005 Paris, France Article Outline C. Macroscopic phenomenological approaches: The active gels Glossary D. Comparisons of the different approaches to de- scribing active polymer solutions I. Definition of the Subject and Its Importance VIII. Extensions and Future Directions II. Introduction Acknowledgments III. The Diversity of Cell Motility Bibliography A. Swimming B. Crawling C. Extensions of cell motility IV. The Cell Cytoskeleton A. Biopolymers B. Molecular motors C. Motor families D. Other cytoskeleton-associated proteins E. Cell anchoring and regulatory pathways F. The prokaryotic cytoskeleton V. Filament-Driven Motility A. Microtubule growth and catastrophes B.
    [Show full text]
  • The Development of a Novel Approach to the Design of Microdevices
    The development of a novel approach to the design of microdevices Submitted in total fulfillment of the requirements for the degree of Doctor of Philosophy by Yulia Alekseeva Faculty of Life and Social Sciences Swinburne University of Technology December 2011 Abstract The effectiveness of protein-based microdevices depends on the ability of their surfaces to provide spatial immobilization and maintain protein bioactivities. Although methodologies for the construction of microdevices for biomedical applications have been developed, the manufacturing of microdevices remains expensive due to the high cost of materials and fabrication processes. As the surfaces display structural uniformities which restrict protein-surface interactions and consequently protein immobilization, innovative approaches to the design of surfaces are required. The approaches need to allow for the minimization of fabrication costs via efficient amplification and spatial immobilization of multiplex proteins so that the bioactivity of protein-based microdevices (e.g., microarrays) can be retained. A novel approach to the design of surfaces for microdevices has been developed and evaluated in this work. This approach is based on micro/nanostructures fabricated via laser ablation of a thin metal layer deposited on a transparent polymer. The structures of a 100 nm-range are represented by „combinatorialized‟ micro/nano- channels that allow amplified protein immobilization in a highly controlled manner. The relationship between the properties of the micro/nano-channel surface topography, physico-chemistry, and protein immobilization, for five, molecularly different proteins, i.e., lysozyme, myoglobin, alpha-chymotrypsin, human serum albumin, and human immunoglobulin has been investigated. Using quantitative fluorescence measurements and atomic force microscopy, protein immobilization on microstructures has been characterized.
    [Show full text]
  • Cellular and Molecular Biophysics Module 14 - Cytoskeleton and Molecular Motors Content Writer: Dr
    Course - PGPathshala-Biophysics Paper 11 - Cellular and molecular Biophysics Module 14 - Cytoskeleton and molecular motors Content Writer: Dr. Karthikeyan Pethusamy, AIIMS, NEW DELHI. Objectives: To understand the role of cytoskeleton & molecular motors To differentiate the three types of cytoskeletal elements To enlist the drugs acting on cytoskeletal elements and their uses To understand the pathological basis of disorders associated with cytoskeletal elements To understand the interaction between cytoskeleton and molecular motor proteins Introduction: The cytoskeleton is a cellular structure that helps cells maintain their shape and internal organization. It also provides mechanical support that enables cells to carry out essential functions like cell- division, anchorage and movement. In this module, we will discuss the cytoskeleton. Cytoskeleton is not a single component. It is made up of network of filamentous proteins. In certain cells, cytoskeletal proteins constitute 80% of total cellular proteins. Cytoskeleton consists of three major class of protein elements namely microfilaments, intermediate filaments and microtubules. Out of these, microfilaments are the thinnest, microtubules are the largest and intermediate filaments are intermediate-sized. 1. Microfilaments Microfilament is formed by actin family of proteins in all eukaryotic cells. Apha, beta, and gamma are the three major actin isoforms. Alpha actin is found in muscles and is involved in muscle contraction. Beta and gamma actins are found in various cells. Microfilaments are composed of two intertwined strands of double helical polymers that are arranged head to tail. Each strand is made up of multiple actin monomers. Microfilaments are dynamic structures which undergo rapid assembly and disassembly. ATP binding promotes the addition of actin monomers.
    [Show full text]
  • The Discovery of the Prokaryotic Cytoskeleton: 25Th Anniversary
    MBoC | RETROSPECTIVE The discovery of the prokaryotic cytoskeleton: 25th anniversary Harold P. Erickson* Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710-3709 ABSTRACT The year 2017 marks the 25th anniversary of the discovery of homologues of Monitoring Editor tubulin and actin in prokaryotes. Before 1992, it was largely accepted that tubulin and actin Keith G. Kozminski were unique to eukaryotes. Then three laboratories independently discovered that FtsZ, a University of Virginia protein already known as a key player in bacterial cytokinesis, had the “tubulin signature se- Received: Nov 21, 2016 quence” present in all α-, β-, and γ-tubulins. That same year, three candidates for bacterial Accepted: Nov 30, 2016 actins were discovered in silico. X-ray crystal structures have since confirmed multiple bacte- rial proteins to be homologues of eukaryotic tubulin and actin. Tubulin and actin were appar- ently derived from bacterial precursors that had already evolved a wide range of cytoskeletal functions. INTRODUCTION The 1970s and 1980s saw extensive research on microtubules G/AGGTGSG sequence conserved in all α-, β-, and γ-tubulins. That and actin. During this period, the consensus developed that sequence, known as the tubulin signature sequence, was believed these cytoskeletal elements were unique to eukaryotes and that to be involved in the binding of GTP in the tubulins. The three nothing related to tubulin or actin existed in bacteria or archae- groups all concluded that the GTP-binding site of FtsZ appeared to ans. This consensus was overthrown in the 1990s when a series of be related to that of tubulins.
    [Show full text]
  • Phd Unimib 708296.Pdf
    1 2 Solo la ricerca dell'impossibile può condurre a ciò che è realizzabile. Anonimo 3 4 Table of contents Chapter 1: General Introduction • The Idiopathic Inflammatory Myopathies • Inflammatory myopathies and infections • Type I and type II interferons and the host defense against viral and bacterial infections • The induction of type I IFNs: the role of Toll-like receptors and cytosolic RNA helicases • Nucleic acid-sensing TLRs: compartimentalization as an effective ploy against autoimmunity • The cytoskeleton • Scope of the thesis Chapter 2: Type I interferon molecules and Toll-like receptors in inflammatory myopathies. Cappelletti C, Baggi F, Zolezzi F, Biancolini D, Beretta O, Severa M, Coccia E, Confalonieri P, Morandi L, Mantegazza E, Bernasconi P. Paper submitted Chapter 3: The kinesin superfamily motor protein KIF4 is associated with immune cell activation in idiopathic inflammatory myopathies. Bernasconi P, Cappelletti C, Navone F, Nessi V, Baggi F, Vernos I, Romaggi S, Confalonieri P, Mora M, Morandi L, Mantegazza R. J Neuropathol Exp Neurol 2008; 67: 624-632 5 Chapter 4: Summary, Conclusions and Future perspectives Chapter 5: Publications Chapter 6: Acknowledgments 6 Chapter 1 Introduction The idiopathic inflammatory myopathies The idiopathic inflammatory myopathies (IIMs) constitute a heterogeneous group of subacute, chronic or acute acquired disorders affecting skeletal muscle, sharing the predominating clinical symptom of muscle weakness and histopathological signs of inflammation in muscle tissue. 1,2 On the basis of clinical, demographic, histological and immunopathological criteria, IIMs are divided in three major and discrete subgroups: dermatomyositis (DM), polymyositis (PM), and sporadic inclusion body myositis (IBM) ( box1 ). There are differences in the age and gender distribution of the three major subtypes of inflammatory myopathies.
    [Show full text]
  • 1 Cover Thai
    การโคลนยีน และการวิเคราะห์ลักษณะของโปรตีน MreB และ FtsZ จากเชือแบคทีเรียบาซิลลัส ซับทิลิส ว่าทีร้อยตรีหญิงสุนารี โชคนัด วิทยานิพนธ์นี%เป็นส่วนหนึงของการศึกษาตามหลักสูตรปริญญาวิทยาศาสตรมหาบัณฑิต สาขาวิชาชีวเคมี มหาวิทยาลัยเทคโนโลยีสุรนารี ปีการศึกษา 2558 GENE CLONING AND CHARACTERIZATION OF MREB AND FTSZ FROM BACILLUS SUBTILIS Sunaree Choknud A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Chemistry Suranaree University of Technology Academic Year 2015 สุนารี โชคนัด : การโคลนยีน และการวิเคราะห์ลักษณะของโปรตีน MreB และ FtsZ จากเชื)อ แบคทีเรียบาซิลลัส ซับทิลิส -.E0E 1230I0. A0D 17A8A1TE8I&ATI30 3F M8EB A0D FTS& F83M BACILLUS SUBTILIS). อาจารย์ทีปรึกษา : อาจารย์ ดร.เศกสิทธิA ชํานาญศิลป์, 105 หน้า. MreB และ Fts& เป็นโปรตีน โครงสร้างของเซลล์แบคทีเรีย MreB มีความสําคัญสําหรับการ ควบคุมทิศทางในการสร้างผนังเซลล์ ในขณะที Fts& มีความจําเป็นในการแบ่งเซลล์ ไม่นานนี)มี รายงานวาทั่ )งสองโปรตีนได้ทําอันตรกิริยากนโดยตรงั บริเวณทีมีการสร้างผนังก)นเซลล์ั แนะให้เห็น วาโปรตีนทั่ )งสองทํางานร่วมกนในการแบั ่งเซลล์และการสร้างผนังเซลล์ การเกิดเป็นเส้นใยของ MreB และ Fts& เป็นขั)นตอนแบบพลวัต โดยทัวไปถูกควบคุมโดยการสลาย= ATR และ .TR ตามลําดับ และการเกิดเป็นเส้นใยของ MreB ทีบริเวณผิวภายในเซลล์นั)น ยังต้องการ Mg2V MreB ทํา หน้าทีเป็นโครงสร้างคํ)ายันเพือเชือมโยงเอนไซม์ peptidoglycan synthases โดยการทําอันตรกิริยา ผานกลุ่ ่มโปรตีนชือ penicillin ainding p oteins Fts& ไม่ได้มีหน้าทีในการสร้างผนังเซลล์โดยตรง เช่นเดียวกบั MreB แต ่ Fts& ทําหน้าทีขับเคลือนการสร้างผนังเซลล์ในระหวางการแบ่ ่งเซลล์ ณ เวลา และสถานทีทีจําเพาะ
    [Show full text]
  • Cytoskeleton - Wikipedia
    6/13/2020 Cytoskeleton - Wikipedia Cytoskeleton The cytoskeleton is a complex, dynamic network of interlinking Cell biology protein filaments present in the The animal cell cytoplasm of all cells, including bacteria and archaea.[1] It extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. In eukaryotes, it is composed of three main components, microfilaments, intermediate filaments and microtubules, and these are all capable of rapid growth or disassembly dependent on the cell's Components of a typical animal cell: requirements.[2] 1. Nucleolus A multitude of functions can be 2. Nucleus performed by the cytoskeleton. Its 3. Ribosome (little dots) primary function is to give the cell its shape and mechanical resistance to 4. Vesicle deformation, and through association 5. Rough endoplasmic reticulum with extracellular connective tissue 6. Golgi apparatus (or, Golgi body) and other cells it stabilizes entire tissues.[3][4] The cytoskeleton can also 7. Cytoskeleton contract, thereby deforming the cell 8. Smooth endoplasmic reticulum and the cell's environment and 9. Mitochondrion allowing cells to migrate.[5] Moreover, it is involved in many cell signaling 10. Vacuole pathways and in the uptake of 11. Cytosol (fluid that contains organelles, extracellular material (endocytosis),[6] comprising the cytoplasm) the segregation of chromosomes 12. Lysosome during cellular division,[3] the 13. Centrosome cytokinesis stage of cell division,[7] as scaffolding to organize the contents of 14. Cell membrane the cell in space[5] and in intracellular transport (for example, the movement of vesicles and organelles within the cell)[3] and can be a template for the construction of a cell wall.[3] Furthermore, it can form specialized structures, such as flagella, cilia, lamellipodia and podosomes.
    [Show full text]
  • Prokaryotic Cells: Structural Organisation of the Cytoskeleton and Organelles
    Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 107(3): 283-293, May 2012 283 Prokaryotic cells: structural organisation of the cytoskeleton and organelles Wanderley de Souza1,2,3 1Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Av. Brigadeiro Trompowsky s/n Bloco G, 21941-900 Rio de Janeiro, RJ, Brasil 2Diretoria de Programas, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brasil 3Instituto Nacional de Metrologia, Qualidade e Tecnologia, Rio de Janeiro, RJ, Brasil For many years, prokaryotic cells were distinguished from eukaryotic cells based on the simplicity of their cy- toplasm, in which the presence of organelles and cytoskeletal structures had not been discovered. Based on current knowledge, this review describes the complex components of the prokaryotic cell cytoskeleton, including (i) tubulin homologues composed of FtsZ, BtuA, BtuB and several associated proteins, which play a fundamental role in cell divi- sion, (ii) actin-like homologues, such as MreB and Mb1, which are involved in controlling cell width and cell length, and (iii) intermediate filament homologues, including crescentin and CfpA, which localise on the concave side of a bacterium and along its inner curvature and associate with its membrane. Some prokaryotes exhibit specialised mem- brane-bound organelles in the cytoplasm, such as magnetosomes and acidocalcisomes, as well as protein complexes, such as carboxysomes. This review also examines recent data on the presence of nanotubes, which are structures that are well characterised in mammalian cells that allow direct contact and communication between cells.
    [Show full text]