Project description:Interventions: ntestinal polyp gruop and colorectal cancer gruop:Nil
Primary outcome(s): bacteria;fungi;archaea;virus
Study Design: Factorial
Project description:Methanococcus maripaludis is a methanogenic Archaea that conserves energy from molecular hydrogen to reduce carbon dioxide to methane. Chemostat grown cultures limited for phosphate or leucine were compared to determine the regulatory response to leucine limitation. Keywords: archaea, hydrogen, leucine, phosphate, nutrient limitation, growth rate, methanogen
Project description:Histones are a principal constituent of chromatin in eukaryotes and fundamental to our understanding of eukaryotic gene regulation. In archaea, histones are phylogenetically widespread but not universal: several archaeal lineages have independently lost histone genes. What prompted or facilitated these losses and how archaea without histones organize their chromatin remains largely unknown. Here, we use micrococcal nuclease digestion of native and reconstituted chromatin to elucidate primary chromatin architecture in an archaeon without histones, the acido-thermophilic archaeon Thermoplasma acidophilum. We confirm and extend prior results showing that T. acidophilum harbours a HU family protein, HTa, that protects part of the genome from MNase digestion. Charting HTa-based chromatin architecture in vitro, in vivo and in an HTa-expressing E. coli strain, we present evidence that HTa is an archaeal histone analog. HTa-protected fragments are GC-rich, display histone-like mono- and dinucleotide patterns around a conspicuous dyad, exhibit relatively invariant positioning throughout the growth cycle, and show archaeal histone-like oligomerization behaviour. Our results suggest that HTa, a DNA-binding protein of bacterial origin, has converged onto an architectural role filled by histones in other archaea.
Project description:Organisms of the third domain of life, the Archaea, share molecular characteristics both with bacteria and eukarya. These organisms attract scientific attention as research models for regulation and evolution of processes such as transcription, translation and RNA processing. We have reconstructed the primary transcriptome of Sulfolobus solfataricus P2, one of the most widely studied model archaeal organisms. Analysis of 625 million bases of sequenced cDNAs yielded a single-bp resolution map of transcription start sites and operon structures for more than 1000 transcriptional units. The analysis led to the discovery of 310 expressed non-coding RNAs, with an extensive expression of overlapping cis-antisense transcripts to a level unprecedented in any bacteria or archaea but resembling that of eukaryotes. As opposed to bacterial transcripts, most Sulfolobus transcripts completely lack 5' UTR sequences, suggesting that mRNA/ncRNA interactions differ between bacteria and archaea. The data also reveal internal hotspots for transcript cleavage linked to RNA degradation, and predict sequence motifs that promote RNA destabilization. This study emphasizes the importance of transcriptome sequencing as a key tool for understanding the mechanisms and extent of RNA-based regulation for bacteria and archaea. 5 samples of cDNA sequencing (2 of these are replicates), and 3 samples of RACE-cDNA sequencing (described in the samples section).
Project description:Structure probing combined with next-generation sequencing (NGS) has provided novel insights into RNA structure-function relationships. To date such studies have focused largely on bacteria and eukaryotes, with little attention given to the third domain of life, archaea. Furthermore, functional RNAs have not been extensively studied in archaea, leaving open questions about RNA structure and function within this domain of life. With archaeal species being diverse and having many similarities to both bacteria and eukaryotes, the archaea domain has the potential to be an evolutionary bridge. In this study, we introduce a method for probing RNA structure in vivo in the archaea domain of life. We investigated the structure of ribosomal RNA (rRNA) from Methanosarcina acetivorans, a well-studied anaerobic archaeal species, grown with either methanol or acetate. After probing the RNA in vivo with dimethyl sulfate (DMS), Structure-seq2 libraries were generated, sequenced, and analyzed. We mapped the reactivity of DMS onto the secondary structure of the ribosome, which we determined independently with comparative analysis, and confirmed the accuracy of DMS probing in M. acetivorans. Accessibility of the rRNA to DMS in the two carbon sources was found to be quite similar, although some differences were found. Overall, this study establishes the Structure-seq2 pipeline in the archaea domain of life and informs about ribosomal structure within M. acetivorans.
Project description:Precise control of the cell cycle is central to the physiology of all cells. In prior work we demonstrated that archaeal cells maintain a constant cell size; however, the regulatory mechanisms underlying the cell cycle remain unexplored in this domain of life. In this study we use genetics, functional genomics, and quantitative imaging to identify and characterize the CdrSL gene regulatory network in a model species of archaea. We demonstrate the central role of these ribbon-helix-helix family transcription factors in the regulation of cell division. In this GEO series related to this study, we use ChIP-seq analysis to demonstrate the binding of CdrL to the upstream region of the cdrS-ftsZ2 locus. We conclude that the CdrSL-Z2 transcriptional network is required to coordinate cell division with cell growth in archaea.
Project description:Organisms of the third domain of life, the Archaea, share molecular characteristics both with bacteria and eukarya. These organisms attract scientific attention as research models for regulation and evolution of processes such as transcription, translation and RNA processing. We have reconstructed the primary transcriptome of Sulfolobus solfataricus P2, one of the most widely studied model archaeal organisms. Analysis of 625 million bases of sequenced cDNAs yielded a single-bp resolution map of transcription start sites and operon structures for more than 1000 transcriptional units. The analysis led to the discovery of 310 expressed non-coding RNAs, with an extensive expression of overlapping cis-antisense transcripts to a level unprecedented in any bacteria or archaea but resembling that of eukaryotes. As opposed to bacterial transcripts, most Sulfolobus transcripts completely lack 5' UTR sequences, suggesting that mRNA/ncRNA interactions differ between bacteria and archaea. The data also reveal internal hotspots for transcript cleavage linked to RNA degradation, and predict sequence motifs that promote RNA destabilization. This study emphasizes the importance of transcriptome sequencing as a key tool for understanding the mechanisms and extent of RNA-based regulation for bacteria and archaea.