Phylogenetic analysis of Group I marine archaeal rRNA sequences emphasizes the hidden diversity within the primary group Archaea.
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ABSTRACT:
SUBMITTER: McInerney JO
PROVIDER: S-EPMC1688723 | biostudies-other | 1997 Nov
REPOSITORIES: biostudies-other
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Project description:In 1992, two independent reports based on small-subunit rRNA gene (SSU rDNA) cloning revealed the presence of novel Archaea among marine bacterioplankton. Here, we report the presence of further novel Archaea SSU rDNA sequences recovered from the midgut contents of a deep-sea marine holothurian. Phylogenetic analyses show that these abyssal Archaea are a paraphyletic component of a highly divergent clade that also includes some planktonic sequences. Our data confirm that this clade is a deep-branching lineage in the tree of life.
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Project description:This SuperSeries is composed of the following subset Series: GSE12923: Halobacterium salinarum NRC-1 growth curve, tiling arrays. GSE12977: Halobacterium salinarum NRC-1 growth curve GSE13108: Halobacterium salinarum NRC-1 conditional ChIP-chip for transcription initiation factor IIB 4 (TFBd) GSE7045: ChIP-Chip of General Transcription factors in Halobacterium NRC-1 GSE15786: Halobacterium sp. NRC-1 ChIP-chip for TFBa, TFBd and TFBf, high resolution array GSE15788: Halobacterium salinarum NRC-1 total RNA hybridization of TFBd overexpression versus Reference sample Despite knowledge of complex prokaryotic transcription mechanisms, generalized rules, such as the simplified organization of genes into operons with well-defined promoters and terminators, have played a significant role in systems analysis of regulatory logic in both bacteria and archaea. Here, we have investigated the prevalence of alternate regulatory mechanisms through genome-wide characterization of transcript structures of ~64% of all genes including putative non-coding RNAs in Halobacterium salinarum NRC-1. Our integrative analysis of transcriptome dynamics and protein-DNA interaction datasets revealed widespread environment-dependent modulation of operon architectures, transcription initiation and termination inside coding sequences, and extensive overlap in 3' ends of transcripts for many convergently transcribed genes. A significant fraction of these alternate transcriptional events correlate to binding locations of 11 transcription factors and regulators (TFs) inside operons and annotated genes - events usually considered spurious or non-functional. With experimental validation, we illustrate the prevalence of overlapping genomic signals in archaeal transcription, casting doubt on the general perception of rigid boundaries between coding sequences and regulatory elements Refer to individual Series
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Project description:In the evolutionary arms race between microbes, their parasites, and their neighbours, the capacity for rapid protein diversification is a potent weapon. Diversity-generating retroelements (DGRs) use mutagenic reverse transcription and retrohoming to generate myriad variants of a target gene. Originally discovered in pathogens, these retroelements have been identified in bacteria and their viruses, but never in archaea. Here we report the discovery of intact DGRs in two distinct intraterrestrial archaeal systems: a novel virus that appears to infect archaea in the marine subsurface, and, separately, two uncultivated nanoarchaea from the terrestrial subsurface. The viral DGR system targets putative tail fibre ligand-binding domains, potentially generating >10(18) protein variants. The two single-cell nanoarchaeal genomes each possess ≥4 distinct DGRs. Against an expected background of low genome-wide mutation rates, these results demonstrate a previously unsuspected potential for rapid, targeted sequence diversification in intraterrestrial archaea and their viruses.
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Project description:Despite knowledge of complex prokaryotic transcription mechanisms, generalized rules, such as the simplified organization of genes into operons with well-defined promoters and terminators, have played a significant role in systems analysis of regulatory logic in both bacteria and archaea. Here, we have investigated the prevalence of alternate regulatory mechanisms through genome-wide characterization of transcript structures of ~64% of all genes including putative non-coding RNAs in Halobacterium salinarum NRC-1. Our integrative analysis of transcriptome dynamics and protein-DNA interaction datasets revealed widespread environment-dependent modulation of operon architectures, transcription initiation and termination inside coding sequences, and extensive overlap in 3' ends of transcripts for many convergently transcribed genes. A significant fraction of these alternate transcriptional events correlate to binding locations of 11 transcription factors and regulators (TFs) inside operons and annotated genes - events usually considered spurious or non-functional. With experimental validation, we illustrate the prevalence of overlapping genomic signals in archaeal transcription, casting doubt on the general perception of rigid boundaries between coding sequences and regulatory elements This SuperSeries is composed of the SubSeries listed below.
2009-06-25 | GSE13150 | GEO
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Project description:Many cyanophage isolates which infect the marine cyanobacteria Synechococcus spp. and Prochlorococcus spp. contain a gene homologous to psbA, which codes for the D1 protein involved in photosynthesis. In the present study, cyanophage psbA gene fragments were readily amplified from freshwater and marine samples, confirming their widespread occurrence in aquatic communities. Phylogenetic analyses demonstrated that sequences from freshwaters have an evolutionary history that is distinct from that of their marine counterparts. Similarly, sequences from cyanophages infecting Prochlorococcus and Synechococcus spp. were readily discriminated, as were sequences from podoviruses and myoviruses. Viral psbA sequences from the same geographic origins clustered within different clades. For example, cyanophage psbA sequences from the Arctic Ocean fell within the Synechococcus as well as Prochlorococcus phage groups. Moreover, as psbA sequences are not confined to a single family of phages, they provide an additional genetic marker that can be used to explore the diversity and evolutionary history of cyanophages in aquatic environments.
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