We hypothesize that the presence of a σB-dependent promoter upstream of sigA ensures that relevant concentrations of σA are present under all metabolic conditions to interact with RNA polymerase, even under conditions of cellular stress (i.e. σB activation). In addition, σB regulation of sigA may also be important for the return of the bacterium from a stress response to a normal transcriptional pattern. In support of this concept, recent studies in Synechocystis PCC66803 demonstrated that induction of one sigma factor altered the transcription of the remaining sigma factors suggesting a transcriptional cross-talk within CCI-779 molecular weight the sigma factor system
[30]. In addition to transcripts A (4.8 kb), B (1.5 kb), C (1.2 kb) and D (1.3 kb), two transcripts E and F were detected using all four probes. However, a transcriptional Tariquidar supplier initiation site for transcripts E and F was not identified using two separate methodologies, specifically primer extension and 5′ RACE. Therefore, we propose that transcripts E and F are processed/degraded products of the larger 4.9 kb transcript A. It is known that the MMSO of E. coli is selectively cleaved by RNaseE [31]; providing additional evidence that transcripts E and F could represent a selleck regulated,
processed form of transcript A. It is possible, although their sizes are indistinguishable, that transcripts E and F detected in exponential phase are unique from that detected in late exponential or stationary phase (i.e. 12-16 hours of growth; Figures 3A-B). However, a potential +1 site for transcripts E and F was not detected using total RNA isolated
from both exponential and stationary Hydroxychloroquine price phase cultures. Clearly, further experimentation is needed to determine the origin and function of transcripts E and F. The conservation of Serp1129 orthologs in three gram-positive species led us to investigate the potential functional role of Serp1129. ATP and GTP binding assays showed that Serp1129 was capable of binding ATP and GTP. Studies of Streptomyces NrdR have shown that the binding of ATP or dATP into a pocket within the protein affect its ability to bind and act as a transcriptional regulator of the ribonucleotide reductases genes [32]. However, it is unknown whether the ability of Serp1129 to bind ATP or GTP functions in regulating transcription of the MMSO during exponential growth. Serp1130 may also play a pivotal role in sensing the energy status of the cell and regulation of replication proteins within S. epidermidis. CBS domains are necessary for the energy sensing mechanism in some proteins such as AMP-activated protein kinase (AMPK) [24, 33, 34]. Recent data from studies in bacteria have demonstrated that the CBS domain within YrbH of Yersinia pestis negatively regulates the organisms ability to produce biofilm by responding to ATP concentrations within the cell [35].