| Abstract: | A genomic analysis of putative penicillin-binding proteins (PBPs) that are involved in the synthesis of the peptidoglycan
layer of the cell wall and are encoded in 12 cyanobacterial genomes was performed in order to help elucidate the role(s) of
these proteins in peptidoglycan synthesis, especially during cyanobacterial cellular differentiation. The analysis suggested
that the minimum set of PBPs needed to assemble the peptidoglycan layer in cyanobacteria probably does not exceed one bifunctional
transpeptidase–transglycosylase Class A high-molecular-weight PBP; two Class B high-molecular-weight PBPs, one of them probably
involved in cellular elongation and the other in septum formation; and one low-molecular-weight PBP. The low-molecular-weight
PBPs of all of the cyanobacteria analyzed are putative endopeptidases and are encoded by fewer genes than in Escherichia coli. We show that in Anabaena sp. strain PCC 7120, predicted proteins All2981 and Alr4579, like Alr5101, are Class A high-molecular-weight PBPs that are
required for the functional differentiation of aerobically diazotrophic heterocysts, indicating that some members of this
class of PBPs are required specifically for cellular developmental processes. |
