Transcriptome and proteome analysis of Bacillus subtilis gene expression in response to superoxide and peroxide stress

The Gram-positive soil bacterium Bacillus subtilis responds to oxidative stress by the activation of different cellular defence mechanisms. These are composed of scavenging enzymes as well as protection and repair systems organized in highly sophisticated networks. In this study, the peroxide and the superoxide stress stimulons of B. subtilis were characterized by means of transcriptomics and proteomics. The results demonstrate that oxidative-stress-responsive genes can be classified into two groups. One group encompasses genes which show similar expression patterns in the presence of both reactive oxygen species. Examples are members of the PerR and the Fur regulon which were induced by peroxide and superoxide stress. Similarly, both kinds of stress stimulated the activation of the stringent response. The second group is composed of genes primarily responding to one stimulus, like the members of the SOS regulon which were particularly upregulated in the presence of peroxide, and many genes involved in sulfate assimilation and methionine biosynthesis which were only induced by superoxide. Several genes encoding proteins of unknown function could be assigned to one of these groups.

A Bacillus subtilis Gene of Previously Unknown Function, yhaG, Is Translationally Regulated by Tryptophan-Activated TRAP and Appears To Be Involved in Tryptophan Transport

ABSTRACT Computer analysis of the Bacillus subtilis genome sequence revealed a gene with no previously attributed function,yhaG, specifying a transcript containing a presumptive binding site for the tryptophan-activated regulatory protein, TRAP. The presumptive TRAP binding site overlaps the yhaGShine-Dalgarno sequence and translation initiation region. TRAP was shown to regulate expression of yhaG translationally. Production of the yhaG transcript in vivo was found to compete for the binding of TRAP to other known TRAP binding sites. YhaG is likely to be a transmembrane protein involved in tryptophan transport.

A Novel Bacillus subtilis Gene,antE, Temporally Regulated and Convergent to and Overlapping dnaE

ABSTRACT A Bacillus subtilis promoter, Px, that functions in a convergent manner with the sigA operon promoter P3 has been found in the sigA operon. Promoter Px is turned on at the same time as promoter P3 during early sporulation. The transcript from promoter Px codes for a small protein with partial homology to the OmpR protein from Escherichia coli and also carries an untranslated sequence at its 3′ end that is complementary to the 5′ end of the P3 transcript, which codes for the ribosome binding site ofdnaE. The gene controlled by Px has been calledantE. The expression of antE does not require ςB, ςE, or ςH. Px was transcribed in vitro by the ςA holoenzyme and is the seventh promoter to be recognized in the ςA operon. A possible role for the antE gene during early sporulation is proposed.