Factor that stimulates resuscitation of dormant cells. Has peptidoglycan (PG) hydrolytic activity. Has little to no effect on actively-growing cells. PG fragments could either directly activate the resuscitation pathway of dormant bacteria or serve as a substrate for endogenous Rpf, resulting in low molecular weight products with resuscitation activity. In pM quantities promotes the resuscitation and growth of dormant, nongrowing cells from M.luteus in addition to Mycobacterium tuberculosis, M.avium, M.bovis, M.kansaii and M.smegmatis. Hydrolyzes endogeneous cell walls, peptidoglycan preparations from Mycobacterium tuberculosis and M.smegmatis as well as an artificial lysozyme substrate 4-methylumbelliferyl-beta-D-N,N',N''-triacetylchitotrioside (MUF tri-NAG). Overexpression in E.coli (when the enzyme is targeted to the periplasm) causes cell lysis. Activity on the artificial substrate MUF tri-NAG is inhibited by 2-nitrophenylthiocyanates (NPT) compounds. Found in culture supernatant, also accumulates on the cell surface. RNA is abundant in early lag phase, decreases by early mid-log phase and is undetectable by stationary phase (48 hours growth). Protein expression is slower; detectable by 5 hours, accumulating during early mid-exponential phase and then gradually disappearing by 50 hours growth (late stationary phase) (at protein level). The LysM domain is not required for resuscitation activity in vitro; in its absence the protein is active in the fM range. May be subject to further C-terminal cleavage as the protein identified in gels is smaller than is expected. Essential, it cannot be disrupted. Belongs to the transglycosylase family. Rpf subfamily.