Probable enzyme that may play an important role in cell wall biology. Cell wall biogenesis; peptidoglycan biosynthesis. Monomer. Probably localized either on the surface of the outer spore membrane and/or in the inner spore coat. Expressed in the mother cell compartment from T4 of sporulation. LysM domains are thought to be involved in peptidoglycan binding. Regulated by SigK. Could also be negatively regulated by GerE. Transcribed by SigK RNA polymerase. Inactivation of the ykuD gene does not affect vegetative growth, spore resistance to heat, chloroform and lysozyme, or spore germination in the presence of L-alanine. Belongs to the YkuD family.