Thermoplasma volcanium GSS1
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Project description:Thermophilic acidophilic archaea
| PRJNA110 | ENA
Project description:We use MNase-Seq to elucidate primary chromatin architecture in an archaeon without histones, the acido-thermophilic archaeon Thermoplasma acidophilum. Like all members of the Thermoplasmatales, T. acidophilum harbours a HU family protein, HTa, that is highly expressed and protects - like histones but unlike well-characterized bacterial HU proteins – a sizeable fraction of the genome from MNase digestion. Comparing HTa-based chromatin architecture to that of three histone-encoding archaea, Methanothermus fervidus, Haloferax volcanii, and Thermococcus kodakkarensis, we present evidence that HTa is an archaeal histone analog. HTa-protected fragments are GC-rich, display histone-like mono- and dinucleotide patterns around the dyad, exhibit relatively invariant positioning throughout the growth cycle, and show archaeal histone-like oligomerization dynamics. Our results suggest that HTa, a DNA-binding protein of bacterial origin, has converged onto an architectural role filled by histones in other archaea.
2019-03-11 | GSE127727 | GEO
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.
2019-10-08 | GSE138576 | GEO
Project description:We use MNase-Seq to elucidate primary chromatin architecture in an archaeon without histones, the acido-thermophilic archaeon Thermoplasma acidophilum. Like all members of the Thermoplasmatales, T. acidophilum harbours a HU family protein, HTa, that is highly expressed and protects - like histones but unlike well-characterized bacterial HU proteins – a sizeable fraction of the genome from MNase digestion. Comparing HTa-based chromatin architecture to that of three histone-encoding archaea, Methanothermus fervidus, Haloferax volcanii, and Thermococcus kodakkarensis, we present evidence that HTa is an archaeal histone analog. HTa-protected fragments are GC-rich, display histone-like mono- and dinucleotide patterns around the dyad, exhibit relatively invariant positioning throughout the growth cycle, and show archaeal histone-like oligomerization dynamics. Our results suggest that HTa, a DNA-binding protein of bacterial origin, has converged onto an architectural role filled by histones in other archaea.
2019-03-11 | GSE127726 | GEO
Project description:Archaea of the order Sulfolobales execute a well-structured cell cycle program similar to that of eukaryotic cells. However, the mechanism of cell cycle regulation remains enigmatic. Here, we show that three essential ribbon-helix-helix domain transcription factors, aCcr1, aCcr2, and aCcr3, play pivotal roles in controlling the cell cycle progression in the thermoacidophilic archaeon Saccharolobus islandicus by licensing the timely transcription of the key genes that define the cell cycle phases. The three transcription factors act as repressors and recognize similar regulatory sequences. However, their expression timing during the cell cycle differs: aCcr1 is expressed immediately after the cell division, aCcr3 during the transition between the G1 and genome replication (S) phase, whereas aCcr2 is expressed throughout the cell cycle. The disengagement of aCcr2 from the recognized promoters prior to the M phase is controlled through its phosphorylation by the cyclically-expressed eukaryotic-like kinase aCcrK (archaea cell cycle regulatory kinase). The synergy between aCcr1, aCcr2, and aCcr3 is also achieved through their differential affinities for the promoters and the levels of protein expression. The global regulation of the Sulfolobales cell cycle may be achieved not through transcriptional activation, but rather by repression of the key genes during strategic moments of the cell cycle. We propose a phosphorylation-assisted braking point model for the cell cycle control in Sulfolobales, which may represent a simple evolutionary intermediate on the way to the more complex cell cycle regulation in eukaryotes.
2026-04-29 | GSE316930 | GEO