Identification and Characterization of a Cell Wall Hydrolase for Sporangiospore Maturation in Actinoplanes missouriensis

In streptomycetes, an aerial hypha is compartmentalized by multiple septations into prespores, which become spores through a series of maturation processes. However, little is known about these maturation processes. The rare actinomyceteActinoplanes missouriensis produces sporangiospores, which are assumed to be formed also from prespores generated by the compartmentalization of intrasporangium hyphae via septation. The identification of GsmA as a cell wall hydrolase for the separation of adjacent spores sheds light on the almost unknown processes of sporangiospore formation inA. missouriensis . Furthermore, the fact that GsmA orthologues are conserved within the genusActinoplanes but not in streptomycetes indicates thatActinoplanes has developed an original strategy for the spore maturation in a specific environment, that is, inside a sporangium.