LytM family endopeptidase LmdC is controlled by regulated auto processing and proteolytic destruction in Pseudomonas aeruginosa
Enzymes that cleave the bacterial peptidoglycan sacculus, known collectively as autolysins, are critical for growth, division and morphogenesis, but their activities must be carefully controlled to avoid catastrophic lysis. Some autolysin control mechanisms have emerged, but we still know little about how most of them are regulated. Here, we report a novel control mechanism for the LytM/M23…
A recently discovered control mechanism regulates the LytM/M23 family endopeptidase PA4404, also known as LmdC, in the bacterium Pseudomonas aeruginosa. This endopeptidase, responsible for cleaving the bacterial peptidoglycan sacculus during growth, division and morphogenesis, must be carefully controlled to prevent catastrophic lysis.
Researchers have found that LmdC undergoes regulated auto processing, where it is first cleaved into N- and C-terminal domains, which are then degraded by the carboxyl-terminal processing proteases Prc and CtpA. Mutations affecting LmdC's interaction with these processing proteases suggest that full-length LmdC is the functional enzyme, with its auto-catalytic cleavage serving only to initiate its proteolytic destruction.
Two proteins, Baf encoded by PA0664 and Api encoded by PA0663, were discovered to inhibit LmdC's auto-catalytic cleavage. It is hypothesized that Baf and Api may promote a location-specific role for LmdC, preventing any potential dangers of free LmdC cleaving peptidoglycan at the wrong site. The co-occurrence and linkage of the lmdC and baf homologs, along with conserved features of those LmdC homologs, indicate that regulated LmdC auto processing is a widely conserved control mechanism.
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