Biosynthetic Pathways Related to Cell Structure and Function

Partha Krishnamurthy; Suhas H. Phadnis; Bruce E. Dunn; Cindy R. Deloney; Raoul S. Rosenthal

doi:10.1128/9781555818005.ch14

Chapter 14 : Biosynthetic Pathways Related to Cell Structure and Function

Authors: Partha Krishnamurthy¹, Suhas H. Phadnis², Bruce E. Dunn², Cindy R. Deloney⁴, Raoul S. Rosenthal⁵

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Affiliations: 1: Department of Pathology, Medical College of Wisconsin, Milwaukee, WI 53226; 2: Department of Pathology, Medical College of Wisconsin, Milwaukee, WI 53226; 3: Pathology and Laboratory Medicine Service, Department of Veterans Affairs Medical Center, Milwaukee, WI 53295–1000; 4: Division of Biomedical Sciences, University of California, Riverside, CA 92521; 5: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202

Content Type: Monograph

Publication Year: 2001

Category: Bacterial Pathogenesis

Book DOI: 10.1128/9781555818005

Chapter DOI: 10.1128/9781555818005.ch14

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Abstract:

The spiral morphology of Helicobacter pylori appears to confer an advantage to the bacterium in the viscous gastric mucus, since its spiral forms move more effectively in media with high viscosity than more conventional rod-shaped organisms. Peptidoglycans are the stress-bearing structures of bacteria that maintain the integrity of the cell wall and the shape of the bacterium. There is an overall decrease in monomers as the bacteria age, while the percentage of dimers, "anhydro" residues, and dipeptide monomers increases. The lack of detectable trimers or tetramers in H. pylori murein indicates that cross-linking does not occur between three or more glycan chains, whereas cross-linking between three or four glycan chains is detectable in E. coli. The presence of pentapeptide as the main fraction of H. pylori muropeptides indicates that it possesses little carboxypeptidase activity. On the basis of protein sequence homologies, the genome of H. pylori appears to code for homologs of all the enzymes involved in the cytoplasmic synthesis of the disaccharide pentapeptide, starting with the synthesis of UDP-N-acetylmuramic acid and finishing with UDP-disaccharide pentapeptide linked to an undecaprenyl lipid carrier. The second step in building the murein sacculus is the polymerization reaction, accompanied by the insertion of the newly made material into the existing peptidoglycan (PG) layer. Analysis of the H. pylori genome shows the presence of genes coding for all the enzymes of the biosynthetic pathway leading to the disaccharide pentapeptide, which is the basic building block of murein.

Citation: Krishnamurthy P, Phadnis S, Dunn B, Deloney C, Rosenthal R. 2001. Biosynthetic Pathways Related to Cell Structure and Function, p 159-166. In Mobley H, Mendz G, Hazell S (ed), Helicobacter pylori. ASM Press, Washington, DC. doi: 10.1128/9781555818005.ch14

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Biosynthetic Pathways Related to Cell Structure and Function

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Figure 1

General composition and age changes in H. pylori PG. As H. pylori cells age from early to late log phase, the composition of their PG changes. The shaded region represents the amino acids that are removed from the PG in late log phase, essentially resulting in a PG with increased dipeptides.

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Figure 1

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Tables

Biosynthetic Pathways Related to Cell Structure and Function

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Table 1

Structure of peptidoglycan isolated from H. pylori strains SP1, 84–183, NCTC 11637 and E. coli MC 4100

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Table 1

Structure of peptidoglycan isolated from H. pylori strains SP1, 84–183, NCTC 11637 and E. coli MC 4100

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Table 2

List of H. pylori 26695 putative genes that are involved in PG biosynthesis

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Table 2

List of H. pylori 26695 putative genes that are involved in PG biosynthesis

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Table 3

H. pylori 26695 ORFs that show sequence motifs of PBPs a

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Table 3

H. pylori 26695 ORFs that show sequence motifs of PBPs a