cell wall synthesis and its importance

1. BACTERIAL CELL WALL
SYNTHESIS
PRESENTED BY,
D.IRENE
16PGZ001
M.Sc.Zoology (spl in Biotechnology)
Lady Doak College,
Madurai.

2. CONTENTS
• Structure of peptidoglycan
• Synthesis of peptidoglycan
• Role of cytoskeleton in cell wall synthesis
• Patterns of cell wall synthesis
• Significance of peptidoglycan cell wall

3. PEPTIDOGLYCAN CELL WALL

4. ULTRA STRUCTURE OF CELL WALL
Gram positive bacterial cell wall
Gram negative bacterial cell wall

5. STRUCTURE OF PEPTIDOGLYCAN

6. SYNTHESIS OF PEPTIDOGLYCAN
SYNTHESIS OF UDP-NAG
Fructose-6-phosphate
glucosamine-1-phosphate
N-Acetylglucosamine-1-phosphate
UDP-NAG
Acetyl-coA
CoA

7. SYNTHESIS OF UDP-NAM
UDP-NAG
UDP-NAM
UDP-NAM Penta peptide
PEP
Pi
NADPH
NADP+
Amino acids are added one at a
time sequentially.

8. Peptidoglycan cell
wall synthesis

9. Bactoprenol unit Pyrophosphate unit

10. TRANSPEPTIDATION
Peptidoglycan Cross-Links. (a) E. coli
peptidoglycan with direct cross-linking, typical of many gram
negative bacteria.
(b) Staphylococcus aureus peptidoglycan. S.aureus is a gram-
positive bacterium. NAM is N-acetylmuramic acid. NAG is N-
acetylglucosamine. Gly is glycine. Although the polysaccharide
chains are drawn opposite each other for the sake of clarity,
two chains lying side-by-side may be linked together

12. ROLE OF CYTOSKELETON IN CELL WALL
SYNTHESIS
• Cytoskeletal structures formed by MreBCD proteins control cell shape by controlling
the cell wall synthesis.
• Any mutations that lead to the defects in bacterial cell shape are directly associated
with a defect in cell wall synthesis.
• Multiple mutations in pbp genes can convert rod shaped E.coli and B.subtilis into
round or branched cells.(Nelson et al.,2000)
• Similarly mutation in TagF (enzyme involved in teichoic acid synthesis) converts
B.subtilis to round cells. (Henriques et al., 1998)

13. • <a href="https://www.researchgate.net/figure/225086120_fig2_Figure-2-MreB-and-
Mbl-mutants-present-specific-morphological-defects-Here-are-presented"><img
src="https://www.researchgate.net/profile/Arnaud_Chastanet/publication/22508612
0/figure/fig2/AS:302571546791942@1449150086790/Figure-2-MreB-and-Mbl-
mutants-present-specific-morphological-defects-Here-are-presented.png"
MreB and Mbl mutants present
specific morphological defects
(Chastanet and Carballido 2012)

14. PATTERNS OF CELL WALL SYNTHESIS
Wall Synthesis Patterns. Patterns of new cell wall synthesis in growing and dividing bacteria.
(a) Streptococci and some other gram-positive cocci.
(b) Synthesis in rod-shaped bacteria (E. coli, Salmonella, Bacillus). The zones of growth are in
turquoise. The actual situation is more complex than indicated because cells can begin to divide
again before the first division is completed

15. SIGNIFICANCE OF PEPTIDOGLYCAN
Osmotic lysis

16. CONCLUSION
• Peptidoglycan wall is crucial for the bacterial growth,
protection and maintenance of the cell shape.
• Cytoskeletons play a crucial role in cell shape
determination but the specific effectors of cell wall
receptors of cell wall morphogenesis controlled by
cytoskeleton is unknown (Scheffers and Pinho, 2005)
• All the factors, responsible for the cell wall synthesis, if
studied it would be effective in designing drugs and
antibiotics.

18. REFERENCES
• Henriques, A. O., P. Glaser, P. J. Piggot, and C. P. Moran, Jr. 1998. Control of cell
shape and elongation by the rodA gene in Bacillus subtilis. Mol.Microbiol. 28:235–
247.
• Honeyman, A. L., and G. C. Stewart. 1989. The nucleotide sequence of the rodC
operon of Bacillus subtilis. Mol. Microbiol. 3:1257–1268.
• Nelson, D. E., and K. D. Young. 2000. Penicillin binding protein 5 affects cell
diameter, contour, and morphology of Escherichia coli. J. Bacteriol.182:1714–1721.
• Arnaud Chastanet and Rut Carballido., The actin-like MreB proteins in Bacillus
subtilis: A new turn., Article in Frontiers in bioscience (Scholar edition) · June 2012
DOI: 10.2741/S354 · Source: PubMed.
• Dirk-Jan Scheffers and Mariana G. Pinho., Bacterial Cell Wall Synthesis: New
Insights from Localization Studies., microbiology and molecular biology reviews,
Dec. 2005, p. 585–607 Vol. 69, No. 4 1092-2172/05/$08.000
doi:10.1128/MMBR.69.4.585–607.2005
• Prescott,Harley and Kleins, Microbiology., 7 edition., McGraw Hill publications.,New