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Effect of DNA binding protein Ssh12 from hyperthermophilic archaeon Sulfolobus shibatae on DNA supercoiling

Science China(Life Sciences) 1999年第4期42卷 401-408页

作者：楼慧强黄力 VietQ.Mai Pomona College CA 91711

An 11.5-ku DNA binding protein, designated as Sshl2, was purified from the hyperthermophilic archaeon Sulfolobus shibatae by column chromatography in SP Sepharose, DNA cellulose and phosphocellulose. Sshl2 accounts for about 4 % of the total cellular protein. The protein is capable of binding to both negatively supercoiled and relaxed DNAs. Nick closure analysis revealed that Sshl2 constrains negative supercoils upon binding to DNA. While the ability of the protein to constrain supercoils is weak at 22℃ , it is enhanced substantially at temperatures higher than 37℃ . Both the cellular content and supercoil-constraining ability of Sshl2 suggest that the protein may play an important role in the organization and stabilization of the chromosome of S. shibatae.

关键词： hyperthermophilic archaea Sulfolobus shibatae DNA binding protein supercoiling.

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Core Metabolic Features and Hot Origin of Bathyarchaeota

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Engineering 2019年第3期5卷 498-504页

作者： Xiaoyuan Feng Yinzhao Wang Rahul Zubin Fengping Wang State Key Laboratory of Microbial Metabolism School of Life Sciences and Biotechnology Shanghai Jiao Tong University Shanghai 200240 China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai 200240 China

The archaeal phylum Bathyarchaeota comprises highly diversified subgroups and is considered to be one of the most abundant microorganisms on earth. The metabolic features and evolution of this phylum still remain largely unknown. In this article, a comparative metabolic analysis of 15 newly reconstructed and 36 published metagenomic assembled genomes (MAGs) spanning 10 subgroups was performed, revealing the core metabolic features of Bathyarchaeota—namely, protein, lipid, and benzoate degradation;glycolysis;and the Wood–Ljungdahl (WL) pathway, indicating an acetyl-CoA-centralized metabolism within this phylum. Furthermore, a partial tricarboxylic acid (TCA) cycle, acetogenesis, and sulfur-related metabolic pathways were found in specific subgroups, suggesting versatile metabolic capabilities and ecological functions of different subgroups. Intriguingly, most of the MAGs from the Bathy-21 and -22 subgroups, which are placed at the phylogenetic root of all bathyarchaeotal lineages and likely represent the ancient Bathyarchaeota types, were found in hydrothermal environments and encoded reverse gyrase, suggesting a hyperthermophilic feature. This work reveals the core metabolic features of Bathyarchaeota, and indicates a hot origin of this archaeal phylum.

关键词： Bathyarchaeota Metagenomics Comparative genomics hyperthermophilic adaptation

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Induction of the Sulfolobus shibatae virus SSV1 DNA replication by mitomycin C

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Chinese Science Bulletin 2002年第11期47卷 923-927页

作者： Danxu Liu Li Huang Chinese Acad Sci State Key Lab Microbial Resources Inst Microbiol Beijing 100080 Peoples R China

The temperate virus SSV1 from the hyper-thermophilic archaeon Sulfolobus shibatae provides a useful model system for the study of archaeal DNA replication. Southern hybridization showed that SSV1 existed primarily as a provirus in its host that was grown without shaking. Upon UV or mitomycin C induction, the cellular level of free SSV1 DNA increased drastically whereas that of integrated viral DNA remained unchanged. The results of mitomycin C induction were more reproducible than those of UV induction. We found that, when the cells that had been grown without shaking were shaken, the replication of SSV1 DNA was also induced. Based on our results, we developed a method for the induction of SSY1 DNA replication by mitomycin C. When the S. shibatae virus production was induced using this method, the cellular level of free SSV1 DNA started to increase 10 h after induction, and peaked after 12-15 h. A fully induced S. shibatae cell contained -50 molecules of free SSV1 DNA. The development of this induction

关键词： hyperthermophilic archaea Sulfolobus shibatae SSV1 DNA replication induction.

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Evolutionary conservation and DNA binding properties of the Ssh7 proteins from Sulfolobus shibatae

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Science China(Life Sciences) 2002年第6期45卷 583-592页

作者：陈绪林郭荣黄力 Ray Hong Pomona College CA91711

The thermoacidophilic archaeon Sulfolobus shibatae synthesizes a large amount of the 7-ku DMA binding proteins known as Ssh7. Our hybridization experiments showed that two Ssh7-encoding genes existed in the genome of S. shibatae. These two genes, designated ssh7a and ssh7b, have been cloned, sequenced and expressed in Escherichia coli. The two Ssh7 proteins differ only at three amino acid positions. In addition, the c/s-regulatory sequences of the ssh7a and ssh7b genes are highly conserved. These results suggest the presence of a selective pressure to maintain not only the sequence but also the expression of the two genes. We have also found that there are two genes encoding the 7-ku protein in Sulfolobus solfataricus. Based on this and other studies, we suggest that the gene encoding the 7-ku protein underwent duplication before the separation of Sulfolobus species. Binding of native Ssh7 and recombinant (r)Ssh7 to short duplex DNA fragments was analyzed by electrophoretic mobility shift assays. Both native and recombinant forms of the protein behaved in a similar fashion in the assays, suggesting that the interaction of Ssh7 with DNA is not affected either by specific lysine methylation found in the native Ssh7 proteins or by the difference between the two Ssh7 isomers in amino acid sequence. Our data show that Ssh7 binds duplex DNA fragments with a binding size of - 6.6 base pairs and an apparent dissociation constant of (0.7-1.0)×10-7 mol/L under the assay conditions employed in the present study. In addition, Ssh7 binds more tightly to negatively supercoiled DNA than to linear or relaxed DNA.

关键词： hyperthermophilic archaea, DNA binding proteins, ssh7a/ssh7b genes, protein-DNA interaction.

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