The Rv1651c-encoded PE-PGRS30 protein expressed in Mycobacterium smegmatis exhibits polar localization and modulates its growth profile

Sequencing analysis of the complete genome of Mycobacterium tuberculosis (Mtb) H37Rv resulted in the identification of a novel multigene, the PE family of genes. The genes of the largest PE-PGRS subfamily of the PE family are mainly restricted to pathogenic mycobacteria, and their exact role in the biology of Mtb is not clearly understood. Based on their sequence homology, PE-PGRS proteins were initially thought to serve common functions. However, studies on individual proteins reveal that the individual proteins of this subfamily could be performing several unrelated tasks. In the present study, we investigated the function of PE-PGRS30 by expressing it in Mycobacterium smegmatis. PE-PGRS30 expression in M. smegmatis resulted in phenotypic changes with altered colony morphology and growth profile. The recombinant PE-PGRS30 showed polar localization and was found to be associated with the cell wall of M. smegmatis. Thus, the present study suggests that the prolonged lag phase of growth caused by the PE-PGRS30 may, in part, contribute to the latency of Mtb.