Project description:Antisense RNAs (asRNAs) are present in diverse organisms and play important roles in gene regulation. In this work, we mapped the primary antisense transcriptome in the halophilic archaeon Halobacterium salinarum NRC-1. By reanalyzing publicly available data, we mapped antisense transcription start sites (aTSSs) and inferred the probable 3' ends of these transcripts. We analyzed the resulting asRNAs according to the size, location, function of genes on the opposite strand, expression levels and conservation. We show that at least 21% of the genes contain asRNAs in H. salinarum. Most of these asRNAs are expressed at low levels. They are located antisense to genes related to distinctive characteristics of H. salinarum, such as bacteriorhodopsin, gas vesicles, transposases and other important biological processes such as translation. We provide evidence to support asRNAs in type II toxin⁻antitoxin systems in archaea. We also analyzed public Ribosome profiling (Ribo-seq) data and found that ~10% of the asRNAs are ribosome-associated non-coding RNAs (rancRNAs), with asRNAs from transposases overrepresented. Using a comparative transcriptomics approach, we found that ~19% of the asRNAs annotated in H. salinarum belong to genes with an ortholog in Haloferax volcanii, in which an aTSS could be identified with positional equivalence. This shows that most asRNAs are not conserved between these halophilic archaea.
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.
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:Given that transition metals are essential cofactors in central biological processes, misallocation of the wrong metal ion to a metalloprotein can have resounding and often detrimental effects on diverse aspects of cellular physiology. Therefore, in an attempt to characterize unique and shared responses to chemically similar metals we have reconstructed physiological behaviors of Halobacterium NRC-1, an archaeal halophile, in sub-lethal levels of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II). Over 20% of all genes responded transiently within minutes of exposure to Fe(II), perhaps reflecting immediate large scale physiological adjustments to maintain homeostasis. At steady state, each transition metal induced growth arrest, attempts to minimize oxidative stress, toxic ion scavenging, increased protein turnover and DNA repair, and modulation of active ion transport. While several of these constitute generalized stress responses, up regulation of active efflux of Co(II), Ni(II), Cu(II), and Zn(II), down regulation of Mn(II) uptake and up regulation of Fe(II) chelation, confer resistance to the respective metals. We have synthesized all these discoveries into a unified systems level model to provide an integrated perspective of responses to six transition metals with emphasis on experimentally verified regulatory mechanisms. Finally, through comparisons across global transcriptional responses to different metals we provide insights into putative in vivo metal selectivity of metalloregulatory proteins and demonstrate that a systems approach can help rapidly unravel novel metabolic potential and regulatory programs of poorly studied organisms. Keywords: time series
Project description:Given that transition metals are essential cofactors in central biological processes, misallocation of the wrong metal ion to a metalloprotein can have resounding and often detrimental effects on diverse aspects of cellular physiology. Therefore, in an attempt to characterize unique and shared responses to chemically similar metals we have reconstructed physiological behaviors of Halobacterium NRC-1, an archaeal halophile, in sub-lethal levels of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II). Over 20% of all genes responded transiently within minutes of exposure to Fe(II), perhaps reflecting immediate large scale physiological adjustments to maintain homeostasis. At steady state, each transition metal induced growth arrest, attempts to minimize oxidative stress, toxic ion scavenging, increased protein turnover and DNA repair, and modulation of active ion transport. While several of these constitute generalized stress responses, up regulation of active efflux of Co(II), Ni(II), Cu(II), and Zn(II), down regulation of Mn(II) uptake and up regulation of Fe(II) chelation, confer resistance to the respective metals. We have synthesized all these discoveries into a unified systems level model to provide an integrated perspective of responses to six transition metals with emphasis on experimentally verified regulatory mechanisms. Finally, through comparisons across global transcriptional responses to different metals we provide insights into putative in vivo metal selectivity of metalloregulatory proteins and demonstrate that a systems approach can help rapidly unravel novel metabolic potential and regulatory programs of poorly studied organisms. Keywords: stress response, dose response
Project description:Given that transition metals are essential cofactors in central biological processes, misallocation of the wrong metal ion to a metalloprotein can have resounding and often detrimental effects on diverse aspects of cellular physiology. Therefore, in an attempt to characterize unique and shared responses to chemically similar metals we have reconstructed physiological behaviors of Halobacterium NRC-1, an archaeal halophile, in sub-lethal levels of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II). Over 20% of all genes responded transiently within minutes of exposure to Fe(II), perhaps reflecting immediate large scale physiological adjustments to maintain homeostasis. At steady state, each transition metal induced growth arrest, attempts to minimize oxidative stress, toxic ion scavenging, increased protein turnover and DNA repair, and modulation of active ion transport. While several of these constitute generalized stress responses, up regulation of active efflux of Co(II), Ni(II), Cu(II), and Zn(II), down regulation of Mn(II) uptake and up regulation of Fe(II) chelation, confer resistance to the respective metals. We have synthesized all these discoveries into a unified systems level model to provide an integrated perspective of responses to six transition metals with emphasis on experimentally verified regulatory mechanisms. Finally, through comparisons across global transcriptional responses to different metals we provide insights into putative in vivo metal selectivity of metalloregulatory proteins and demonstrate that a systems approach can help rapidly unravel novel metabolic potential and regulatory programs of poorly studied organisms. Keywords: stress response, dose response
Project description:Given that transition metals are essential cofactors in central biological processes, misallocation of the wrong metal ion to a metalloprotein can have resounding and often detrimental effects on diverse aspects of cellular physiology. Therefore, in an attempt to characterize unique and shared responses to chemically similar metals we have reconstructed physiological behaviors of Halobacterium NRC-1, an archaeal halophile, in sub-lethal levels of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II). Over 20% of all genes responded transiently within minutes of exposure to Fe(II), perhaps reflecting immediate large scale physiological adjustments to maintain homeostasis. At steady state, each transition metal induced growth arrest, attempts to minimize oxidative stress, toxic ion scavenging, increased protein turnover and DNA repair, and modulation of active ion transport. While several of these constitute generalized stress responses, up regulation of active efflux of Co(II), Ni(II), Cu(II), and Zn(II), down regulation of Mn(II) uptake and up regulation of Fe(II) chelation, confer resistance to the respective metals. We have synthesized all these discoveries into a unified systems level model to provide an integrated perspective of responses to six transition metals with emphasis on experimentally verified regulatory mechanisms. Finally, through comparisons across global transcriptional responses to different metals we provide insights into putative in vivo metal selectivity of metalloregulatory proteins and demonstrate that a systems approach can help rapidly unravel novel metabolic potential and regulatory programs of poorly studied organisms. Keywords: stress response, dose response
Project description:Given that transition metals are essential cofactors in central biological processes, misallocation of the wrong metal ion to a metalloprotein can have resounding and often detrimental effects on diverse aspects of cellular physiology. Therefore, in an attempt to characterize unique and shared responses to chemically similar metals we have reconstructed physiological behaviors of Halobacterium NRC-1, an archaeal halophile, in sub-lethal levels of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II). Over 20% of all genes responded transiently within minutes of exposure to Fe(II), perhaps reflecting immediate large scale physiological adjustments to maintain homeostasis. At steady state, each transition metal induced growth arrest, attempts to minimize oxidative stress, toxic ion scavenging, increased protein turnover and DNA repair, and modulation of active ion transport. While several of these constitute generalized stress responses, up regulation of active efflux of Co(II), Ni(II), Cu(II), and Zn(II), down regulation of Mn(II) uptake and up regulation of Fe(II) chelation, confer resistance to the respective metals. We have synthesized all these discoveries into a unified systems level model to provide an integrated perspective of responses to six transition metals with emphasis on experimentally verified regulatory mechanisms. Finally, through comparisons across global transcriptional responses to different metals we provide insights into putative in vivo metal selectivity of metalloregulatory proteins and demonstrate that a systems approach can help rapidly unravel novel metabolic potential and regulatory programs of poorly studied organisms. Keywords: stress response, dose response
Project description:Given that transition metals are essential cofactors in central biological processes, misallocation of the wrong metal ion to a metalloprotein can have resounding and often detrimental effects on diverse aspects of cellular physiology. Therefore, in an attempt to characterize unique and shared responses to chemically similar metals we have reconstructed physiological behaviors of Halobacterium NRC-1, an archaeal halophile, in sub-lethal levels of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II). Over 20% of all genes responded transiently within minutes of exposure to Fe(II), perhaps reflecting immediate large scale physiological adjustments to maintain homeostasis. At steady state, each transition metal induced growth arrest, attempts to minimize oxidative stress, toxic ion scavenging, increased protein turnover and DNA repair, and modulation of active ion transport. While several of these constitute generalized stress responses, up regulation of active efflux of Co(II), Ni(II), Cu(II), and Zn(II), down regulation of Mn(II) uptake and up regulation of Fe(II) chelation, confer resistance to the respective metals. We have synthesized all these discoveries into a unified systems level model to provide an integrated perspective of responses to six transition metals with emphasis on experimentally verified regulatory mechanisms. Finally, through comparisons across global transcriptional responses to different metals we provide insights into putative in vivo metal selectivity of metalloregulatory proteins and demonstrate that a systems approach can help rapidly unravel novel metabolic potential and regulatory programs of poorly studied organisms. Keywords: stress response, dose response