Peptidoglycan hydrolase LytF plays a role in cell separation with Cw1F during vegetative growth of Bacillus subtilis

Peptidoglycan hydrolase, LytF (CwIE), was determined to be identical to Yhd D (deduced cell wall binding protein) by zymography after insertional inact ivation of the yhdD gene. YhdD exhibits high sequence similarity with CwIF (PapQ, LytE) and p60 of Listeria monocytogenes. The N-terminal region of Yh dD has a signal sequence followed by five tandem repeated regions containin g polyserine residues. The C-terminal region corresponds to the catalytic d omain, because a truncated protein without the N-terminal region retained c ell wall hydrolase activity. The histidine-fagged LytF protein produced in Escherichia coli cells hydrolyzed the linkage of D-gamma-glutamyl-meso-diam inopimelic acid in murein peptides, indicating that it is a D,L-endopeptida se. Northern hybridization and primer extension analyses indicated that the lytF gene was transcribed by E sigma(D) RNA polymerase. Disruption of lytF led to slightly filamentous cells, and a lytF cwlF double mutant exhibited extraordinary microfiber formation, which is similar to the cell morpholog y of the cwlF sigD mutant.