Molecular genetic characterisation of whiB3, a mycobacterial homologue of a Streptomyces sporulation factor

WhiB is an essential sporulation factor in Streptomyces coelicolor. We repo rt here the molecular genetic characterisation of whiB3, a whiB-like gene i n the nonspore-forming Mycobacterium smegmatis mc(2)155. M. smegmatis whiB3 encodes a 96-amino-acid protein with 81% similarity to its M. tuberculosis counterpart identified in the genome project, and 35% similarity to S. coe licolor WhiB. In both mycobacteria, whiB3 is flanked by the same upstream g ene, Rv3415c, and appears to be monocistronic. Promoter probe analyses sugg est that the whiB3 gene is expressed constitutively. Disruption of whiB3 di d not affect growth or the dormancy response of M. smegmatis. (C) Elsevier, Paris.