Microm 410 Fall 2009: Prokaryotic Structure/Function part 1 Dr. Matt Parsek

Organization of the Prokaryotic Cell Prokaryotic Structures

fimbriae

Size Range of Prokaryotes

bacillus See Table 4.1

(rigid) vibrio Nanobacteria 0.05‐0.2 µm (0.14‐0.2 µm) (flexible) Thiomargarita namibiensis Mycoplasma are 700‐750 µm (Fig. 4.2) pleomorphic green alga Nanochlorum eukaryotum Mycoplasma 0.1‐ ~1-2 µm in diameter 0.3 µm Fig. 4.1 Microm 410 Fall 2009: Prokaryotic Structure/Function part 1 Dr. Matt Parsek

Staining cells for Microscopic observation Cell Arrangements

Motility- ~80% of prokaryotes are motile

streptococcus Staining properties: Gram Stain

staphylococcus Fig. 2.3

Gram Stain (1884) (Bacteria)

Gram-negative mixed culture Gram-positive Fig. 2.3 and 2.4 Microm 410 Fall 2009: Prokaryotic Structure/Function part 1 Dr. Matt Parsek

Functions of the cytoplasmic membrane The phospholipid bi‐layer

Fig. 4.9 Fig. 4.4

What is the structure of bacterial phospholipids? Other components of the cytoplasmic membrane

Figs. 4.5‐4.6 Microm 410 Fall 2009: Prokaryotic Structure/Function part 1 Dr. Matt Parsek

Archaeal membranes can be a monolayer Archaeal phospholipids have an ether linkage

Fig. 4.7 Fig. 4.8

Importance of Cell Wall Schematic diagram cell wall

• Provides rigidity to cell allowing cell to withstand the large osmotic/ionic Fig. 4.16 changes a bacterium may experience in its environment, and turgor pressure of cytoplasm (conc. of solutes in cytoplasm).

Cell lysis • May have a role in shape determination.

• Provides a barrier against certain toxic chemical and biological agents.

• Site of action of some of the most commonly used antibiotics used to treat bacterial infections ( family).

• A component of cell wall of Bacteria is responsible for some of symptoms associated with an infection, e.g. fever response (lipopolysaccharide and lipoteichoic acid). Microm 410 Fall 2009: Prokaryotic Structure/Function part 1 Dr. Matt Parsek

Prokaryotes Lacking a Cell Wall Functions of Cell Wall Structure

• The mollicutes group of Bacteria (5 genera, Mycoplasma) • Provides shape (?) and rigidity Properties of group: • Involved in cell wall biosynthesis - Sensitive to osmotic lysis • Involved in cell division (protoplast/sphereoplast) - Resistant to antibiotics directed at cell wall biosynthesis • Involved in motility () • Influences permeability (teichoic acid, LPS, OCWM) - pleomorphic Methanotrophs - contain sterols in membrane similar to those found in • LPS may inhibit phagocytosis membranes of animal cells. • LPS and lipoteichoic acid elicit symptoms of Gram-negative ‐ some are parasites of plants and animals. and positive bacteria infection, respectively.

• L-forms of Bacteria M. pneumoniae

• Certain Archaea (Thermoplasma)

Cell-walled Prokaryotes Gram-positive Gram-negative

~40-90% of wall is Outer cell wall membrane • Contain peptidoglycan peptidoglycan ~5-10%

All cells in the domain Bacteria contain peptidoglycan with exception of Planctomyces and Chlamydia

• Lack peptidoglycan

All cell-walled Archaea Murein layer

C. trachomatis- intracellular parasite; leading cause of blindness in world. Energy parasite Has genes for peptidoglycan synthesis and ATP synthase but does not express genes! Fig. 4.16 Microm 410 Fall 2009: Prokaryotic Structure/Function part 1 Dr. Matt Parsek

Gram-negative Gram-positive NAG NAM

Peptidoglycan strand

L-lysine

DAP

DAP L-lysine Fig. 4.29 Fig. 4.17

Cross-linking of Adjacent Peptidoglycan Strands Peptidoglycan Synthesis

Murein sacculus

Fig. 4.19 Fig. 6.7a Microm 410 Fall 2009: Prokaryotic Structure/Function part 1 Dr. Matt Parsek Peptidoglycan Synthesis Cross-linking of Peptidoglycan Strands cytoplasm cell membrane cell wall autolysins Bactoprenol-P Pi UDP-NAM M G pentapeptide G M Bactoprenol Bactoprenol-P-P P M UMP G P NAM G M Transpeptidase (FtsI) pentapeptide M G UDP-NAG Bactoprenol G P NAM‐NAG P NAM-NAG UMP D-Ala pentapeptide Fig. 6.7b D-alanine carboxypeptidase tRNA-aa Interbridge peptide

Peptidoglycan Synthesis Cross-linking of Peptidoglycan Strands cytoplasm cell membrane cell wall

autolysins Bactoprenol-P Pi UDP-NAM M G pentapeptide G D- Bactoprenol M (Oxamycin) Bactoprenol-P-P P M UMP G β-lactams P NAM G transpeptidase M penicillins and cephalosporins pentapeptide M G UDP-NAG Bactoprenol G P NAM‐NAG P NAM-NAG pentapeptide UMP D-Ala pentapeptide Fig. 6.5 D-alanine carboxypeptidase tRNA-aa Interbridge peptide Microm 410 Fall 2009: Prokaryotic Structure/Function part 1 Dr. Matt Parsek

Antibiotic Resistance

• Inactivate antibiotic β-lactamase (penicillinase)

Clavulanic acid Augmentin and Trimentin (combination of and or respectively)

• Change chemistry of target site

• Limit access of the antibiotic to target site