double-psi beta-barrel fold of endolytic peptidoglycan transglycosylase RlpA and similar proteins
Endolytic peptidoglycan transglycosylase RlpA (rare lipoprotein A, RlpA) is a lytic transglycosylase with a strong preference for naked glycan strands that lack stem peptides. It adopts a double-psi beta-barrel (DPBB) fold and is one of four SPOR-domain containing proteins in Escherichia coli (including FtsN, DedA and DamX) that bind peptidoglycan (PG) and are targeted to the septum during division. It directly interacts with the divisome protein FtsK in vitro, and deletion of the rlpA gene partially bypasses the requirement for functional FtsK, a large, multi-spanning membrane protein that facilitates double-stranded DNA translocation during division and sporulation in E. coli and Bacillus subtilis, respectively. In Pseudomonas aeruginosa, RlpA contributes to rod shape maintenance and daughter cell separation. The separation of daughter cells requires extensive PG remodeling. It has been suggested that amidases and RlpA work in tandem to degrade PG in the division septum and lateral wall to facilitate daughter cell separation.
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