A PEPTIDOGLYCAN HYDROLASE SIMILAR TO BACTERIOPHAGE ENDOLYSINS ACTS ASAN AUTOLYSIN IN NEISSERIA-GONORRHOEAE

We have identified a gene encoding an autolysin (atlA) from Neisseria gonorrhoeae. The deduced amino acid sequence of AtlA shows significant similarity to the peptidoglycan degrading transglycosylases (endolysi ns) of bacteriophages lambda and P2, suggesting that the encoded prote in also functions in peptidoglycan hydrolysis. An atlA mutant was iden tical to the wild-type strain in exponential growth rate, but demonstr ated reduced lysis and peptidoglycan turnover in the stationary phase of growth. When transferred into a buffer solution, at a pH non-permis sive for other gonococcal autolysins, an autolytic activity was detect able in the wild-type strain that was not present in the mutant. The m ost dramatic phenotype of the mutant occurred after extended time in s tationary phase. After approximately 16 h in stationary phase, both st rains underwent an apparent replication event, after which the wild-ty pe strain died rapidly whereas the atlA mutant survived considerably l onger. Even after both the wild-type and mutant cells were dead, many of the mutant cells maintained intact morphology, whereas the wild-typ e cells were lysed, These results suggest that AtlA is a peptidoglycan transglycosylase related to bacteriophage endolysins and acts as an a utolysin in the stationary phase.