Functional Analysis of Essential Peptidoglycan Degrading Enzymes Localized at Bacterial Cellular Sidewall, and Development of Novel Antibiotics Inhibiting the Enzymes

Project: Research project

Project Details

Description

A bacterial cell is covered with peptidoglycan (PG) sacculus, which behaves as an exoskeleton of the cell, and protects the cell from environmental stresses. However, PG sacculus must change its shape during cell proliferation keeping with the sacculus. Accordingly, both the synthesis and disassembly of PG are required during bacterial cell growth to accomplish such shape changing. The bacterial genes, lytE, cwlO, spr, ydhO, and yebA have been shown to encode PG degrading enzymes. According to ours and other's previous study, a depletion of LytE and CwlO in Bacillus subtilis and a depletion of Spr, YdhO, and YebA in Escherichia coli cause lethality of the bacterial cell, which may be due to the defect in cell elongation. We speculate that these enzymes are involved in disassembly of bacterial PG sacculus. Therefore, functional characterizations of these enzymes may facilitate the development of novel antibiotic reagents. In addition, we have found a proteinous inhibitor (IseA) for PG degrading enzymes from B. subtilis, and determined the three-dimensional structure of this inhibitor protein. The overall structure of IseA is similar with a "bow", and the inhibition center locates at the string part of the bow, which is an exposed linear peptide chain. Such a structure led us propose that also a chemically synthesized short polypeptide with the sequence of the inhibition center can inhibit the PG degrading enzymes. Therefore, I'll develop a peptidyl inhibitor according to the structure of IseA. Furthermore, according to our preliminary data and homologous comparison, catalytic domains of the PG degrading enzymes from B. subtilis and E. coli show significant similarity. Therefore, these enzymes are potential targets for developing new antimicrobial reagents, which can be commonly applied to both Gram negative and positive bacteria. Then, we plan to identify common functional features of the PG degrading enzymes in B. subtilis and E. coli. Specific aim 1: To reveal a physiological function of peptidoglycan degrading enzymes from B. subtilis for peptidoglycan sacculus formation. Specific aim 2: To identify common features between essential peptidoglycan degrading enzymes from B. subtilis and E. coli. Specific aim 3: To develop a peptidyl inhibitor for the essential peptidoglycan degrading enzymes.
StatusFinished
Effective start/end date13-04-0114-07-31

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