Figure 2.

Transcriptional regulation of some of the flagellar genes described in Brucella at locus I. (A) Repression of flagellar expression in B. melitensis is linked by the repressor RpoE1 (and other unknown proteins) to ftcR. This master regulator allows FlaF to be expressed and inhibits the expression of fliC and fltB. (B) The expression of a unipolar flagellum in B. melitensis is linked to FtcR, a direct regulator of flagellar protein expression; this is partially activated by the regulator VjbR, which is involved in quorum sensing and the expression of the type-IV secretion system. (C) In Brucella abortus, when the ybeY gene (BAB2_1156), an endoribonuclease, is deleted, there is an overexpression of the FtcR and this results in an increase in flagellin.