High-resolution analysis of chromosome conformation in hyperthermophilic archaea.
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ABSTRACT:
SUBMITTER: Takemata N
PROVIDER: S-EPMC8170502 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Chromosome organization in archaea has long been enigmatic due, in part, to the typically small cell size of archaea and the extremophilic nature of many of the model archaeal species studies, rendering live-cell imaging technically challenging. To circumvent these problems, we recently applied chromosome conformation capture combined with biotin enrichment and deep sequencing (Hi-C) to members of hyperthermophilic archaeal genus Sulfolobus. Our optimized Hi-C protocol described here permits delineation of how Sulfolobus species organize their chromosomes. For complete details on the use and execution of this protocol, please refer to Takemata et al. (2019).
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Project description:To date, no experimental data has been reported for the metallome of hyperthermophilic microorganisms although their metal requirements for growth are known to be unique. Here, experiments were conducted to determine (i) cellular trace metal concentrations of the hyperthermophilic Archaea Methanococcus jannaschii and Pyrococcus furiosus, and (ii) a first estimate of the metallome for these hyperthermophilic species via ICP-MS. The metal contents of these cells were compared to parallel experiments using the mesophilic bacterium Escherichia coli grown under aerobic and anaerobic conditions. Fe and Zn were typically the most abundant metals in cells. Metal concentrations for E. coli grown aerobically decreased in the order Fe > Zn > Cu > Mo > Ni > W > Co. In contrast, M. jannaschii and P. furiosus show almost the reverse pattern with elevated Ni, Co, and W concentrations. Of the three organisms, a biosignature is potentially demonstrated for the methanogen M. jannaschii that may, in part, be related to the metallome requirements of methanogenesis. The bioavailability of trace metals more than likely has varied through time. If hyperthermophiles are very ancient, then the trace metal patterns observed here may begin to provide some insights regarding Earth's earliest cells and in turn, early Earth chemistry.
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Project description:Homologous recombination events between circular chromosomes, occurring during or after replication, can generate dimers that need to be converted to monomers prior to their segregation at cell division. In Escherichia coli, chromosome dimers are converted to monomers by two paralogous site-specific tyrosine recombinases of the Xer family (XerC/D). The Xer recombinases act at a specific dif site located in the replication termination region, assisted by the cell division protein FtsK. This chromosome resolution system has been predicted in most Bacteria and further characterized for some species. Archaea have circular chromosomes and an active homologous recombination system and should therefore resolve chromosome dimers. Most archaea harbour a single homologue of bacterial XerC/D proteins (XerA), but not of FtsK. Therefore, the role of XerA in chromosome resolution was unclear. Here, we have identified dif-like sites in archaeal genomes by using a combination of modeling and comparative genomics approaches. These sites are systematically located in replication termination regions. We validated our in silico prediction by showing that the XerA protein of Pyrococcus abyssi specifically recombines plasmids containing the predicted dif site in vitro. In contrast to the bacterial system, XerA can recombine dif sites in the absence of protein partners. Whereas Archaea and Bacteria use a completely different set of proteins for chromosome replication, our data strongly suggest that XerA is most likely used for chromosome resolution in Archaea.
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Project description:Chromosome conformation capture-based methods such as Hi-C have become mainstream techniques for the study of the 3D organization of genomes. These methods convert chromatin interactions reflecting topological chromatin structures into digital information (counts of pair-wise interactions). Here, we describe an updated protocol for Hi-C (Hi-C 2.0) that integrates recent improvements into a single protocol for efficient and high-resolution capture of chromatin interactions. This protocol combines chromatin digestion and frequently cutting enzymes to obtain kilobase (kb) resolution. It also includes steps to reduce random ligation and the generation of uninformative molecules, such as unligated ends, to improve the amount of valid intra-chromosomal read pairs. This protocol allows for obtaining information on conformational structures such as compartment and topologically associating domains, as well as high-resolution conformational features such as DNA loops.
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Project description:Chromosome conformation capture (3C) provides an adaptable tool through which to study diverse biological questions. Currently, 3C techniques provide either low-resolution interaction profiles across the entire genome, e.g. HiC, or high-resolution interaction profiles at up to several hundred loci, e.g. NG Capture-C and 4C-seq. Generation of high-resolution, genome-wide interaction profiles can feasibly be achieved through efficiency improvements to current high-resolution methods. To this end we systematically tested and removed areas inefficiency in NG Capture-C to develop a new method Nuclear Capture-C, which provides a 300% increase in informative sequencing content. Using Nuclear Capture-C we target 8,026 erythroid promoters in triplicate, showing that this method can achieve high-resolution genome-wide 3C interaction profiles at scale.
2020-10-28 | GSE160229 | GEO
Project description:In this paper, we introduce sequence-based multiscale modeling for biomolecular data analysis. We employ spectral clustering method in our modeling and reveal the difference between sequence-based global scale clustering and local scale clustering. Essentially, two types of distances, i.e., Euclidean (or spatial) distance and genomic (or sequential) distance, can be used in data clustering. Clusters from sequence-based global scale models optimize spatial distances, meaning spatially adjacent loci are more likely to be assigned into the same cluster. Sequence-based local scale models, on the other hand, result in clusters that optimize genomic distances. That is to say, in these models, sequentially adjoining loci tend to be cluster together. We propose two sequence-based multiscale models (SeqMMs) for the study of chromosome hierarchical structures, including genomic compartments and topological associated domains (TADs). We find that genomic compartments are determined only by global scale information in the Hi-C data. The removal of all the local interactions within a band region as large as 10 Mb in genomic distance has almost no significant influence on the final compartment results. Further, in TAD analysis, we find that when the sequential scale is small, a tiny variation of diagonal band region in a contact map will result in a great change in the predicted TAD boundaries. When the scale value is larger than a threshold value, the TAD boundaries become very consistent. This threshold value is highly related to TAD sizes. By the comparison of our results with those previously obtained using a spectral clustering model, we find that our method is more robust and reliable. Finally, we demonstrate that almost all TAD boundaries from both clustering methods are local minimum of a TAD summation function.
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Project description:Encapsidation of genetic material into polyhedral particles is one of the most common structural solutions employed by viruses infecting hosts in all three domains of life. Here, we describe a new virus of hyperthermophilic archaea, Sulfolobus polyhedral virus 1 (SPV1), which condenses its circular double-stranded DNA genome in a manner not previously observed for other known viruses. The genome complexed with virion proteins is wound up sinusoidally into a spherical coil which is surrounded by an envelope and further encased by an outer polyhedral capsid apparently composed of the 20-kDa virion protein. Lipids selectively acquired from the pool of host lipids are integral constituents of the virion. None of the major virion proteins of SPV1 show similarity to structural proteins of known viruses. However, minor structural proteins, which are predicted to mediate host recognition, are shared with other hyperthermophilic archaeal viruses infecting members of the order Sulfolobales The SPV1 genome consists of 20,222 bp and contains 45 open reading frames, only one-fifth of which could be functionally annotated.IMPORTANCE Viruses infecting hyperthermophilic archaea display a remarkable morphological diversity, often presenting architectural solutions not employed by known viruses of bacteria and eukaryotes. Here we present the isolation and characterization of Sulfolobus polyhedral virus 1, which condenses its genome into a unique spherical coil. Due to the original genomic and architectural features of SPV1, the virus should be considered a representative of a new viral family, "Portogloboviridae."
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