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A New Insight Into Role of Phosphoketolase Pathway in Synechocystis Sp
www.nature.com/scientificreports OPEN A new insight into role of phosphoketolase pathway in Synechocystis sp. PCC 6803 Anushree Bachhar & Jiri Jablonsky* Phosphoketolase (PKET) pathway is predominant in cyanobacteria (around 98%) but current opinion is that it is virtually inactive under autotrophic ambient CO2 condition (AC-auto). This creates an evolutionary paradox due to the existence of PKET pathway in obligatory photoautotrophs. We aim to answer the paradox with the aid of bioinformatic analysis along with metabolic, transcriptomic, fuxomic and mutant data integrated into a multi-level kinetic model. We discussed the problems linked to neglected isozyme, pket2 (sll0529) and inconsistencies towards the explanation of residual fux via PKET pathway in the case of silenced pket1 (slr0453) in Synechocystis sp. PCC 6803. Our in silico analysis showed: (1) 17% fux reduction via RuBisCO for Δpket1 under AC-auto, (2) 11.2–14.3% growth decrease for Δpket2 in turbulent AC-auto, and (3) fux via PKET pathway reaching up to 252% of the fux via phosphoglycerate mutase under AC-auto. All results imply that PKET pathway plays a crucial role under AC-auto by mitigating the decarboxylation occurring in OPP pathway and conversion of pyruvate to acetyl CoA linked to EMP glycolysis under the carbon scarce environment. Finally, our model predicted that PKETs have low afnity to S7P as a substrate. Metabolic engineering of cyanobacteria provides many options for producing valuable compounds, e.g., acetone from Synechococcus elongatus PCC 79421 and butanol from Synechocystis sp. strain PCC 68032. However, certain metabolites or overproduction of intermediates can be lethal. Tere is also a possibility that required mutation(s) might be unstable or the target bacterium may even be able to maintain the fux distribution for optimal growth balance due to redundancies in the metabolic network, such as alternative pathways. -
UV-B Induced Stress Responses in Three Rice Cultivars
BIOLOGIA PLANTARUM 54 (3): 571-574, 2010 BRIEF COMMUNICATION UV-B induced stress responses in three rice cultivars I. FEDINA1*, J. HIDEMA2, M. VELITCHKOVA3, K. GEORGIEVA1 and D. NEDEVA1 Institute of Plant Physiology1 and Institute of Biophysics3, Bulgarian Academy of Sciences, Academic Georgi Bonchev Street, Building 21, Sofia 1113, Bulgaria Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan2 Abstract UV-B responses of three rice (Oryza sativa L.) cultivars (Sasanishiki, Norin 1 and Surjamkhi) with different photolyase activity were investigated. Carbon dioxide assimilation data support that Sasanishiki was less sensitive to UV-B than Norin 1 and Surjamkhi. UV-B radiation sharply decreased the content of Rubisco protein in Surjamkhi and has no effect in Sasanishiki. The photochemical activities of photosystem (PS) 1 and PS 2 was slightly affected by UV-B treatment. The content of H2O2 and the activities of antioxidant enzymes, catalase (CAT), peroxides (POX) and superoxide dismutase (SOD) were enhanced after UV-B treatment. The activities of CAT and POX isoenzymes in Sasanishiki were more enhanced by UV-B radiation than those in Norin 1 and Surjamkhi. 14 Additional key words: catalase, CO2 fixation, hydrogen peroxide, peroxidase, Rubisco, superoxide dismutase. ⎯⎯⎯⎯ UV-B sensitivity of plants is determined by the balance of Furthermore, transgenic rice plants in which the CPD damage incurred and by the efficiency of repair processes photolyase was overexpressed had higher CPD photolyase that can restore the impaired functions. This balance is activity and showed significantly greater resistance to influenced by several factors, including the genetic UV-B than wild plants (Hidema et al. -
Synthesis of Tryptophan from Indole, Pyruvate, and Ammonia (E
Proc. Nat. Acad. S&i. USA Vol. 69, No. 5, pp. 1086-1090, May 1972 Reversibility of the Tryptophanase Reaction: Synthesis of Tryptophan from Indole, Pyruvate, and Ammonia (E. coli/a-aminoacrylate/Michaelis-Menten kinetics/pyridoxal 5'-phosphate) TAKEHIKO WATANABE AND ESMOND E. SNELL Department of Biochemistry, University of California, Berkeley, Calif. 94720 Contributed by Esmond E. Snell, February 14, 1972 ABSTRACT Degradation of tryptophan to indole, tain substituted indoles. Reactions 1-3 were shown (4)t to pro- pyruvate, and ammonia by tryptophanase (EC 4 ....) from ceed through a common intermediate, probably an enzyme- Escherichia coli, previously thought to be an irreversible reaction, is readily reversible at high concentrations of bound a-aminoacrylic acid, which could either decompose to pyruvate and ammonia. Tryptophan and certain of its pyruvate and ammonia (in reactions 1 and 2) or add indole to analogues, e.g., 5-hydroxytryptophan, can be synthesized form tryptophan (in reaction 3). At concentrations previously by this reaction from pyruvate, ammonia, and indole or an tested, reactions 1 and 2 were irreversible (4). appropriate derivative at maximum velocities approaching to Yamada et al. those of the degradative reactions. Concentrations of Subsequent these investigations, (5-7) ammonia required for the synthetic reactions produce showed that 0-tyrosinase from Escherichia intermedia cata- specific changes in the spectrum of tryptophanase that lyzes reaction 4 but not reaction 1, and is similar in many differ from those produced by K+ and indicate that am- respects to tryptophanase. monia interacts with bound pyridoxal 5'-phosphate to form an imine. Kinetic results indicate that pyruvate is Tyrosine + H20 Phenol + Pyruvate + NH3 (4) the second substrate bound, hence indole must be the too, catalyzes degradation of serine, cysteine, etc. -
B Number Gene Name Mrna Intensity Mrna Present # of Tryptic
list list sample) short list predicted B number Gene name assignment mRNA present mRNA intensity Gene description Protein detected - Membrane protein detected (total list) detected (long list) membrane sample Proteins detected - detected (short list) # of tryptic peptides # of tryptic peptides # of tryptic peptides # of tryptic peptides # of tryptic peptides Functional category detected (membrane Protein detected - total Protein detected - long b0003 thrB 6781 P 9 P 3 3 P 3 0 homoserine kinase Metabolism of small molecules b0004 thrC 15039 P 18 P 10 P 11 P 10 0 threonine synthase Metabolism of small molecules b0008 talB 20561 P 20 P 13 P 16 P 13 0 transaldolase B Metabolism of small molecules b0009 mog 1296 P 7 0 0 0 0 required for the efficient incorporation of molybdate into molybdoproteins Metabolism of small molecules b0014 dnaK 13283 P 32 P 23 P 24 P 23 0 chaperone Hsp70; DNA biosynthesis; autoregulated heat shock proteins Cell processes b0031 dapB 2348 P 16 P 3 3 P 3 0 dihydrodipicolinate reductase Metabolism of small molecules b0032 carA 9312 P 14 P 8 P 8 P 8 0 carbamoyl-phosphate synthetase, glutamine (small) subunit Metabolism of small molecules b0048 folA 1588 P 7 P 1 2 P 1 0 dihydrofolate reductase type I; trimethoprim resistance Metabolism of small molecules peptidyl-prolyl cis-trans isomerase (PPIase), involved in maturation of outer b0053 surA 3825 P 19 P 4 P 5 P 4 P(m) 1 GenProt membrane proteins (1st module) Cell processes b0054 imp 2737 P 42 P 5 0 0 P(m) 5 GenProt organic solvent tolerance Cell processes b0071 leuD 4770 -
Taming the Wild Rubisco: Explorations in Functional Metagenomics
Taming the Wild RubisCO: Explorations in Functional Metagenomics DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Brian Hurin Witte, M.S. Graduate Program in Microbiology The Ohio State University 2012 Dissertation Committee : F. Robert Tabita, Advisor Joseph Krzycki Birgit E. Alber Paul Fuerst Copyright by Brian Hurin Witte 2012 Abstract Ribulose bisphosphate carboxylase/oxygenase (E.C. 4.1.1.39) (RubisCO) is the most abundant protein on Earth and the mechanism by which the vast majority of carbon enters the planet’s biosphere. Despite decades of study, many significant questions about this enzyme remain unanswered. As anthropogenic CO2 levels continue to rise, understanding this key component of the carbon cycle is crucial to forecasting feedback circuits, as well as to engineering food and fuel crops to produce more biomass with few inputs of increasingly scarce resources. This study demonstrates three means of investigating the natural diversity of RubisCO. Chapter 1 builds on existing DNA sequence-based techniques of gene discovery and shows that RubisCO from uncultured organisms can be used to complement growth in a RubisCO-deletion strain of autotrophic bacteria. In a few short steps, the time-consuming work of bringing an autotrophic organism in to pure culture can be circumvented. Chapter 2 details a means of entirely bypassing the bias inherent in sequence-based gene discovery by using selection of RubisCO genes from a metagenomic library. Chapter 3 provides a more in-depth study of the RubisCO from the methanogenic archaeon Methanococcoides burtonii. -
B Number Gene Name Mrna Intensity Mrna
sample) total list predicted B number Gene name assignment mRNA present mRNA intensity Gene description Protein detected - Membrane protein membrane sample detected (total list) Proteins detected - Functional category # of tryptic peptides # of tryptic peptides # of tryptic peptides detected (membrane b0002 thrA 13624 P 39 P 18 P(m) 2 aspartokinase I, homoserine dehydrogenase I Metabolism of small molecules b0003 thrB 6781 P 9 P 3 0 homoserine kinase Metabolism of small molecules b0004 thrC 15039 P 18 P 10 0 threonine synthase Metabolism of small molecules b0008 talB 20561 P 20 P 13 0 transaldolase B Metabolism of small molecules chaperone Hsp70; DNA biosynthesis; autoregulated heat shock b0014 dnaK 13283 P 32 P 23 0 proteins Cell processes b0015 dnaJ 4492 P 13 P 4 P(m) 1 chaperone with DnaK; heat shock protein Cell processes b0029 lytB 1331 P 16 P 2 0 control of stringent response; involved in penicillin tolerance Global functions b0032 carA 9312 P 14 P 8 0 carbamoyl-phosphate synthetase, glutamine (small) subunit Metabolism of small molecules b0033 carB 7656 P 48 P 17 0 carbamoyl-phosphate synthase large subunit Metabolism of small molecules b0048 folA 1588 P 7 P 1 0 dihydrofolate reductase type I; trimethoprim resistance Metabolism of small molecules peptidyl-prolyl cis-trans isomerase (PPIase), involved in maturation of b0053 surA 3825 P 19 P 4 P(m) 1 GenProt outer membrane proteins (1st module) Cell processes b0054 imp 2737 P 42 P 5 P(m) 5 GenProt organic solvent tolerance Cell processes b0071 leuD 4770 P 10 P 9 0 isopropylmalate -
Commentary. in the Article “Genetic Code Origins: Experi- Ments Confirm Phylogenetic Predictions and May Explain a Puzzle” B
5890 Corrections Proc. Natl. Acad. Sci. USA 96 (1999) Commentary. In the article “Genetic code origins: Experi- Neurobiology. In the article “Growth factor-mediated Fyn ments confirm phylogenetic predictions and may explain a signaling regulates a-amino-3-hydroxy-5-methyl-4-isox- puzzle” by Paul Schimmel and Lluis Ribas de Pouplana, which azolepropionic acid (AMPA) receptor expression in rodent appeared in number 2, January 19, 1999 of Proc. Natl. Acad. neocortical neurons” by Mako Narisawa-Saito, Alcino J. Silva, Sci. USA (96, 327–328), the following corrections should be Tsuyoshi Yamaguchi, Takashi Hayashi, Tadashi Yamamoto, noted. The fifth and sixth sentences of the first paragraph on and Hiroyuki Nawa, which appeared in number 5, March 2, page 328 should read as follows (changes are indicated by bold 1999, of Proc. Natl. Acad. Sci. USA (96, 2461–2466), due to a type): “This base pair is found in the spirochetes T. pallidum printer’s error, there were several errors in the author and and B. burgdorferi that contain a class I enzyme. In contrast, affiliations lines. The correct affiliations are as follows: Ibba et al. (1) show that the class II E. coli enzyme cannot MAKO NARISAWA-SAITO*†,ALCINO J. SILVA‡,TSUYOSHI accept G2-U71.” Also, the word “spirocytes” in the sixth YAMAGUCHI*, TAKASHI HAYASHI§,TADASHI YAMAMOTO§, sentence of the second paragraph on page 328 should read AND HIROYUKI NAWA*†‡ spirochetes. Finally, the sixth sentence of the last paragraph on page 328 should read as follows: “So multiple lateral gene *Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan; ‡Cold Spring Harbor Laboratory, Cold transfer from archaebacteria to certain bacteria could account Spring Harbor, NY 11724; and §Institute of Medical Science, University of for the presence of class I LysRS in bacterial organisms such Tokyo, Tokyo 108-8639, Japan as T. -
The Mechanism of Rubisco Catalyzed Carboxylation Reaction: Chemical Aspects Involving Acid-Base Chemistry and Functioning of the Molecular Machine
catalysts Review The Mechanism of Rubisco Catalyzed Carboxylation Reaction: Chemical Aspects Involving Acid-Base Chemistry and Functioning of the Molecular Machine Immacolata C. Tommasi Dipartimento di Chimica, Università di Bari Aldo Moro, 70126 Bari, Italy; [email protected] Abstract: In recent years, a great deal of attention has been paid by the scientific community to improving the efficiency of photosynthetic carbon assimilation, plant growth and biomass production in order to achieve a higher crop productivity. Therefore, the primary carboxylase enzyme of the photosynthetic process Rubisco has received considerable attention focused on many aspects of the enzyme function including protein structure, protein engineering and assembly, enzyme activation and kinetics. Based on its fundamental role in carbon assimilation Rubisco is also targeted by the CO2-fertilization effect, which is the increased rate of photosynthesis due to increasing atmospheric CO2-concentration. The aim of this review is to provide a framework, as complete as possible, of the mechanism of the RuBP carboxylation/hydration reaction including description of chemical events occurring at the enzyme “activating” and “catalytic” sites (which involve Broensted acid- base reactions) and the functioning of the complex molecular machine. Important research results achieved over the last few years providing substantial advancement in understanding the enzyme functioning will be discussed. Citation: Tommasi, I.C. The Mechanism of Rubisco Catalyzed Keywords: enzyme carboxylation reactions; enzyme acid-base catalysis; CO2-fixation; enzyme Carboxylation Reaction: Chemical reaction mechanism; potential energy profiles Aspects Involving Acid-Base Chemistry and Functioning of the Molecular Machine. Catalysts 2021, 11, 813. https://doi.org/10.3390/ 1. Introduction catal11070813 The increased amount of anthropogenic CO2 emissions since the beginning of the industrial era (starting around 1750) has significantly affected the natural biogeochemical Academic Editor: Arnaud Travert carbon cycle. -
Supplementary Information
Supplementary information (a) (b) Figure S1. Resistant (a) and sensitive (b) gene scores plotted against subsystems involved in cell regulation. The small circles represent the individual hits and the large circles represent the mean of each subsystem. Each individual score signifies the mean of 12 trials – three biological and four technical. The p-value was calculated as a two-tailed t-test and significance was determined using the Benjamini-Hochberg procedure; false discovery rate was selected to be 0.1. Plots constructed using Pathway Tools, Omics Dashboard. Figure S2. Connectivity map displaying the predicted functional associations between the silver-resistant gene hits; disconnected gene hits not shown. The thicknesses of the lines indicate the degree of confidence prediction for the given interaction, based on fusion, co-occurrence, experimental and co-expression data. Figure produced using STRING (version 10.5) and a medium confidence score (approximate probability) of 0.4. Figure S3. Connectivity map displaying the predicted functional associations between the silver-sensitive gene hits; disconnected gene hits not shown. The thicknesses of the lines indicate the degree of confidence prediction for the given interaction, based on fusion, co-occurrence, experimental and co-expression data. Figure produced using STRING (version 10.5) and a medium confidence score (approximate probability) of 0.4. Figure S4. Metabolic overview of the pathways in Escherichia coli. The pathways involved in silver-resistance are coloured according to respective normalized score. Each individual score represents the mean of 12 trials – three biological and four technical. Amino acid – upward pointing triangle, carbohydrate – square, proteins – diamond, purines – vertical ellipse, cofactor – downward pointing triangle, tRNA – tee, and other – circle. -
Overexpression of an Agave Phosphoenolpyruvate Carboxylase Improves Plant Growth and Stress Tolerance
cells Article Overexpression of an Agave Phosphoenolpyruvate Carboxylase Improves Plant Growth and Stress Tolerance Degao Liu 1,2,†, Rongbin Hu 1,† , Jin Zhang 1,2 , Hao-Bo Guo 3, Hua Cheng 1 , Linling Li 1, Anne M. Borland 1,4 , Hong Qin 3, Jin-Gui Chen 1,2, Wellington Muchero 1,2, Gerald A. Tuskan 1,2 and Xiaohan Yang 1,2,* 1 Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA; [email protected] (D.L.); [email protected] (R.H.); [email protected] (J.Z.); [email protected] (H.C.); [email protected] (L.L.); [email protected] (A.M.B.); [email protected] (J.-G.C.); [email protected] (W.M.); [email protected] (G.A.T.) 2 The Center for Bioenergy Innovation (CBI), Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 3 Department of Computer Science and Engineering, SimCenter, University of Tennessee Chattanooga, Chattanooga, TN 37403, USA; [email protected] (H.-B.G.); [email protected] (H.Q.) 4 School of Natural and Environmental Science, Newcastle University, Newcastle upon Tyne NE1 7RU, UK * Correspondence: [email protected]; Tel.: +1-865-241-6895; Fax: +1-865-576-9939 † These authors contribute equally to this work. Abstract: It has been challenging to simultaneously improve photosynthesis and stress tolerance in plants. Crassulacean acid metabolism (CAM) is a CO2-concentrating mechanism that facilitates plant adaptation to water-limited environments. We hypothesized that the ectopic expression of a CAM- specific phosphoenolpyruvate carboxylase (PEPC), an enzyme that catalyzes primary CO2 fixation in Citation: Liu, D.; Hu, R.; Zhang, J.; CAM plants, would enhance both photosynthesis and abiotic stress tolerance. -
Physiological Effects of a Constitutive Tryptophanase in Bacillus Alvei
JOURNAL OF BACTE1RIOLOGY, Sept., 1965 Vol. 90, No. 3 Copyright @ 1965 American Society for Microbiology Printed in U.S.A, Physiological Effects of a Constitutive Tryptophanase in Bacillus alvei J. A. HOCH AND R. D. DEMOSS Department of Microbiology, University of Illinois, Urbana, Illinois Received for publication 8 April 1965 ABSTRACT HOCH, J. A. (University of Illinois, Urbana), AND R. D. DEMoss. Physiological effects of a constitutive tryptophanase in Bacillus alvei. J. Bacteriol. 90:604-610. 1965. -Tryptophanase synthesis in B. alvei is not under the control of tryptophan and is not subject to catabolite repression. Exogenously supplied tryptophan was converted to indole by tryptophanase, and was excreted into the culture medium. The amount of indole excreted was dependent upon the concentration of tryptophan supplied. At intermediate levels of tryptophan (5 to 15 ,jg/ml), the excreted indole was completely reutilized by the cell, in contrast to the result with higher levels. Indole reutil zation was shown to be dependent upon a functional tryptophan synthetase. In the absience of exogenous tryptophan, indole was excreted into the culture medium at an earlier phys- iological age. The early indole was shown not to be a consequence of tryptophanase action. The early indole accompanied uniformly the normal process of tryptophan biosynthesis, and the fission of indole-3-glycerol phosphate was suggested as the origin of the excreted indole. The enzyme tryptophanase from Escherichia MATERIALS AND METHODS coli has been the subject of considerable research Bacteria. B. alvei ATCC 6348 was obtained from in recent years (Burns and DeMoss, 1962; New- the American Type Culture Collection. -
Greater Efficiency of Photosynthetic Carbon Fixation Due to Single Amino
ARTICLE Received 7 Aug 2012 | Accepted 16 Jan 2013 | Published 26 Feb 2013 DOI: 10.1038/ncomms2504 OPEN Greater efficiency of photosynthetic carbon fixation due to single amino-acid substitution Judith Katharina Paulus1,*, Daniel Schlieper1,* & Georg Groth1 The C4-photosynthetic carbon cycle is an elaborated addition to the classical C3-photo- synthetic pathway, which improves solar conversion efficiency. The key enzyme in this pathway, phosphoenolpyruvate carboxylase, has evolved from an ancestral non- photosynthetic C3 phosphoenolpyruvate carboxylase. During evolution, C4 phosphoe- nolpyruvate carboxylase has increased its kinetic efficiency and reduced its sensitivity towards the feedback inhibitors malate and aspartate. An open question is the molecular basis of the shift in inhibitor tolerance. Here we show that a single-point mutation is sufficient to account for the drastic differences between the inhibitor tolerances of C3 and C4 phosphoenolpyruvate carboxylases. We solved high-resolution X-ray crystal structures of a C3 phosphoenolpyruvate carboxylase and a closely related C4 phosphoenolpyruvate carboxylase. The comparison of both structures revealed that Arg884 supports tight inhibitor binding in the C3-type enzyme. In the C4 phosphoenolpyruvate carboxylase isoform, this arginine is replaced by glycine. The substitution reduces inhibitor affinity and enables the enzyme to participate in the C4 photosynthesis pathway. 1 Cluster of Excellence on Plant Sciences (CEPLAS), Institute of Biochemical Plant Physiology, Heinrich Heine University, Universitaetsstr. 1, 40225 Du¨sseldorf, Germany. * These authors contributed equally to this work. Correspondence and requests for materials should be addressed to G.G. (email: [email protected]). NATURE COMMUNICATIONS | 4:1518 | DOI: 10.1038/ncomms2504 | www.nature.com/naturecommunications 1 & 2013 Macmillan Publishers Limited.