Breaking the silence-role of MucR as a virulence determinant in Brucella.

The Zn finger protein MucR is an H-NS-like protein that serves as a gene silencer and nucleoid-structuring protein in the α-proteobacteria. MucR is also an essential virulence determinant in Brucella, where it directly and indirectly controls the expression of many genes required for the virulence of these bacteria in their mammalian hosts, including those encoding the Type IV secretion system and its effectors, the autotransporter adhesins BtaE and BmaC, and the quorum sensing regulators VjbR and BabR. Experimental evidence suggests that one of the primary functions of the Brucella MucR is to ensure that virulence genes are only expressed when their corresponding gene products provide fitness benefits to these bacteria during their infectious lifecycle, and we propose that this function is central to the well-established role of MucR as a virulence determinant.