Slightly enriched at the septal ring. Cells are shorter in a single mutant, while triple envC-nlpD-ygeR disruptions have defects in septation and cell separation and form long filaments (15-fold longer) and further yet by the quadruple disruption mutant (envC-nlpD-mepM(yebA)-ygeR, over 21-fold longer). Quadruple mutants are less sensitive to ampicillin lysis. Belongs to the peptidase M23B family. Extended N-terminus.