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.
Project description:Experimentally mapped transcriptome structure of H. salinarum NRC-1 by hybridizing total RNA (including RNA species <200 nt) to genome-wide high-density tiling arrays (60 mer probes with 40 nt overlap between contiguous probes). H. salinarum NRC-1 presents a number of interesting switches in metabolism during growth due to complex changes in EFs including pH, oxygen, nutrition, etc. While most single perturbations (radiation, oxygen, metals, etc.) affect the expression of only ~10% of all genes (Baliga et al, 2004; Kauret al , 2006; Whitehead et al, 2006), the changes during growth resulted in differential regulation of a significantly higher proportion of genes (~63%, 1,518 genes). These conditions enabled the investigation of a wider transcriptional landscape, which includes not only modulation of transcript levels, but also extensive changes in transcriptome structure. We observed altered transcription start sites (TSSs), transcription termination site (TTSs), operon organizations and differential regulation of putative ncRNAs. By integrating hybridization signals with dynamic growth-related changes, we estimated the probability that each tiling array probe was complementary to a transcribed region, mapped locations of putative transcript boundaries and identified 1,574 TSSs and 1,952 TTSs for most genes with some transcriptional variation. In sum, TSSs were assigned to 64% (1,156 singletons and 544 genes in 203 operons) of all annotated genes and TTSs were assigned to 1,114 genes and 202 operons. We were also able to identify 5' and 3' UTRs and revise start sites for 61 genes and 12 operons.