rho is not essential for viability or virulence in Staphylococcus aureus

We have identified the gene for transcription termination factor Rho in Sta phylococcus aureus, Deletion of rho in S. aureus reveals that it is not ess ential for viability or virulence, We also searched the available bacterial genomic sequences for homologs of Rho and found that it is broadly distrib uted and highly conserved. Exceptions include Streptococcus pneumoniae, Str eptococcus pyogenes, Mycoplasma genitalium, Mycoplasma pneumoniae, Ureaplas ma urealyticum, and Synechocystis sp, strain PCC6803, all of which appear n ot to possess a Rho homolog. Complementation studies indicate that S, aureu s Rho possesses the same activity as Escherichia coli Rho and that the Rho inhibitor bicyclomycin is active against S, aureus Rho, Our results explain the lack of activity of bicyclomycin against many gram-positive bacteria a nd raise the possibility that the essentiality of rho may be the exception rather than the rule.