ABSTRACT
The publication of the complete genome sequences of several Brucella species allowed us to make a survey of the genomic information available on the regulation of gene expression and hence on the possible control of virulence. We identified 146 transcriptional regulators in the genome of B. melitensis. More than fifty percent of these are located on the small chromosome that, however, represents only one third of the total genome. With regard to two-component signal transduction systems, B. melitensis contains nineteen predicted histidine kinases and twenty one predicted response regulators allowing the formation of between ten and twelve pairs of proteins. The unmatched ones either belong to a phosphorelay system or are orphans. A phosphoenolpyruvafe-dependent phosphotransferase transduction pathway also appears to be present and is predicted to function in a way resembling the phosphotransferase systems of Gram-positive bacteria. With regard to specialised global regulators, B. melitensis has five sigma factors in addition to the housekeeping sigma 70 factor, two quorum-sensing linked regulators and one regulator involved in the stringent response. Where possible, we compared the organisation of the mutated locus in the α Proteobacteria and tried to predict putative functions by using, as the starting point, the previously reported attenuation of B. melitensis mutants in regulatory factors.
“ Name me someone that’s not a parasite
and I’ll go out and say a prayer for him “
(Bob Dylan, 1966, “Vision of Johanna”)
