This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Priyadarshini, R. Articles by Young, K. D. Search for Related Content PubMed PubMed Citation Articles by Priyadarshini, R. Articles by Young, K. D.

Daughter Cell Separation by Penicillin-Binding Proteins and Peptidoglycan Amidases in Escherichia coli

Department of Microbiology and Immunology, University of North Dakota School of Medicine, Grand Forks, North Dakota 58202-9037,¹ Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia 24061²

Received 5 April 2006/ Accepted 13 May 2006

As one of the final steps in the bacterial growth cycle, daughter cells must be released from one another by cutting the shared peptidoglycan wall that separates them. In Escherichia coli, this delicate operation is performed by several peptidoglycan hydrolases, consisting of multiple amidases, lytic transglycosylases, and endopeptidases. The interactions among these enzymes and the molecular mechanics of how separation occurs without lysis are unknown. We show here that deleting the endopeptidase PBP 4 from strains lacking AmiC produces long chains of unseparated cells, indicating that PBP 4 collaborates with the major peptidoglycan amidases during cell separation. Another endopeptidase, PBP 7, fulfills a secondary role. These functions may be responsible for the contributions of PBPs 4 and 7 to the generation of regular cell shape and the production of normal biofilms. In addition, we find that the E. coli peptidoglycan amidases may have different substrate preferences. When the DD-carboxypeptidase PBP 5 was deleted, thereby producing cells with higher levels of pentapeptides, mutants carrying only AmiC produced a higher percentage of cells in chains, while mutants with active AmiA or AmiB were unaffected. The results suggest that AmiC prefers to remove tetrapeptides from peptidoglycan and that AmiA and AmiB either have no preference or prefer pentapeptides. Muropeptide compositions of the mutants corroborated this latter conclusion. Unexpectedly, amidase mutants lacking PBP 5 grew in long twisted chains instead of straight filaments, indicating that overall septal morphology was also defective in these strains.

This article has been cited by other articles:

• Park, J. T., Uehara, T. (2008). How Bacteria Consume Their Own Exoskeletons (Turnover and Recycling of Cell Wall Peptidoglycan). Microbiol. Mol. Biol. Rev. 72: 211-227 [Abstract] [Full Text]  
• Uehara, T., Park, J. T. (2008). Growth of Escherichia coli: Significance of Peptidoglycan Degradation during Elongation and Septation. J. Bacteriol. 190: 3914-3922 [Abstract] [Full Text]  
• Derouaux, A., Wolf, B., Fraipont, C., Breukink, E., Nguyen-Disteche, M., Terrak, M. (2008). The Monofunctional Glycosyltransferase of Escherichia coli Localizes to the Cell Division Site and Interacts with Penicillin-Binding Protein 3, FtsW, and FtsN. J. Bacteriol. 190: 1831-1834 [Abstract] [Full Text]  
• Priyadarshini, R., de Pedro, M. A., Young, K. D. (2007). Role of Peptidoglycan Amidases in the Development and Morphology of the Division Septum in Escherichia coli. J. Bacteriol. 189: 5334-5347 [Abstract] [Full Text]  
• Kenyon, W. J., Nicholson, K. L., Rezuchova, B., Homerova, D., Garcia-del Portillo, F., Finlay, B. B., Pallen, M. J., Kormanec, J., Spector, M. P. (2007). {sigma}s-Dependent carbon-starvation induction of pbpG (PBP 7) is required for the starvation-stress response in Salmonella enterica serovar Typhimurium. Microbiology 153: 2148-2158 [Abstract] [Full Text]