Transcriptomic and phenotypic characterization of a Bacillus subtilis strain without extracytoplasmic function ? factors.

ABSTRACT: Bacillus subtilis encodes seven extracytoplasmic function (ECF) ? factors. Three (?(M), ?(W), and ?(X)) mediate responses to cell envelope-active antibiotics. The functions of ?(V), ?(Y), ?(Z), and ?(YlaC) remain largely unknown, and strong inducers of these ? factors and their regulons have yet to be defined. Here, we define transcriptomic and phenotypic differences under nonstress conditions between a strain carrying deletions in all seven ECF ? factor genes (the ?7ECF mutant), a ?MWX triple mutant, and the parental 168 strain. Our results identify >80 genes as at least partially dependent on ECF ? factors, and as expected, most of these are dependent on ?(M), ?(W), or ?(X), which are active at a significant basal level during growth. Several genes, including the eps operon encoding enzymes for exopolysaccharide (EPS) production, were decreased in expression in the ?7ECF mutant but affected less in the ?MWX mutant. Consistent with this observation, the ?7ECF mutant (but not the ?MWX mutant) showed reduced biofilm formation. Extending previous observations, we also note that the ?MWX mutant is sensitive to a variety of antibiotics and the ?7ECF mutant is either as sensitive as, or slightly more sensitive than, the ?MWX strain to these stressors. These findings emphasize the overlapping nature of the seven ECF ? factor regulons in B. subtilis, confirm that three of these (?(M), ?(W), and ?(X)) play the dominant role in conferring intrinsic resistance to antibiotics, and provide initial insights into the roles of the remaining ECF ? factors.

SUBMITTER: Luo Y 

PROVIDER: S-EPMC2953670 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature