Regulation of the 18-kDa heat shock protein in Mycobacterium ulcerans: An alpha-crystallin orthologue that promotes biofilm formation

Abstract

Mycobacterium ulcerans is the causative agent of the debilitating skin disease Buruli ulcer, which is most prevalent in Western and Central Africa. M. ulcerans shares >-98% DNA sequence identity with Mycobacterium marinum, however, M. marinum produces granulomatous, but not ulcerative, lesions in humans and animals. Here we report the differential expression of a small heat shock protein (Hsp18) between strains of M. ulcerans (Hsp18+) and M. marinum (Hsp18-) and describe the molecular basis for this difference. We show by gene deletion and GFP reporter assays in M. marinum that a divergently transcribed gene called hspR_2, immediately upstream of hsp18, encodes a MerR-like regulatory protein..