Project description:To investigate the contribution of ribonucleases to post-transcriptional regulation of mRNA levels, we examined the fitness consequences and gene expression changes of ribonuclease mutants in the extreme halophilic archaeon Halobacterium salinarum NRC-1. H. salinarum NRC-1 is known to use a large repertoire of environment-specific transcriptional regulatory programs, which may be complemented by post-transcriptional regulatory mechanisms. Homology searches identified putative RNase genes in H. salinarum NRC-1 that include likely orthologs for RNases found in prokaryotic and eukaryotic lineages. The VNG2099C protein sequence is significantly similar (e = 2 x 10^-34) to the sequence of the rat liver perchloric acid-soluble protein (L-PSP), which has been shown to have endoribonuclease activity in vitro (Morishita et al 1999). The VNG2099C protein, like the archaeal Sulfolobus tokodaii YjgF/L-PSP protein for which a crystal structure has been solved (Miyakawa et al 2006), shares conservation of residues proposed to constitute the active site of the rat protein. The purpose of this gene expression study was to investigate the role of the putative endoribonuclease VNG2099C on gene regulation.
Project description:Halobacterium salinarum NRC-1 was grown in CM media, at 37oC in a waterbath with agitation of 125 rpm under constant light. Analysis of transcriptional changes during growth, in addition to mapping of transcriptome structure under the same conditions, provided interesting insights about regulatory logic within prokaryotic coding regions.
Project description:Previous work characterized TrmB as a global glucose responsive metabolic transcription factor in archaeal extremophiles. However, it remains unclear how TrmB dynamically regulates its ~100 metabolic enzyme-coding genes. Using a dynamic perturbation approach, we elucidate the topology of the metabolic GRN in Halobacterium salinarum. We assayed gene expression in a wild-type and trmB knockout strain before and immedeatly following glucose perturbation. Clustering dynamic gene expression patterns reveals that TrmB functions alone to regulate central metabolic enzyme-coding genes, but cooperates with various regulators to control peripheral metabolic pathways.