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論文

Draft genome sequence of the radioresistant bacterium ${it Deinococcus grandis}$, isolated from freshwater fish in Japan

佐藤 勝也; 小野寺 威文*; 面曽 宏太*; 武田-矢野 喜代子*; 片山 豪*; 大野 豊; 鳴海 一成*

Genome Announcements (Internet), 4(1), p.e01631-15_1 - e01631-15_2, 2016/01

https://doi.org/10.1128/genomeA.01631-15

${it Deinococcus grandis}$ was isolated as a gram-negative, red-pigmented, radioresistant, rod-shaped bacterium from freshwater fish. The draft genome sequence of ${it D. grandis}$ ATCC 43672 was 4,092,497 bp, with an average G+C content of 67.5% and comprised of 4 circular contigs and 3 linear contigs that was deposited at DDBJ/EMBL/Genbank under the accession number BCMS00000000. The draft genome sequence indicates that ${it D. grandis}$ possesses a DNA damage response regulator (encoded by ${it pprI}$ homolog) and radiation-desiccation response regulons (${it recA}$, ${it ddrA}$, ${it ddrO}$, ${it pprA}$ and ${it gyrA}$ homologs etc.), which are involved in the unique radiation-desiccation response system in ${it D. radiodurans}$. As it is for ${it D. radiodurans}$, ${it D. grandis}$ seems to employ the same radioresistant mechanisms. In future, the draft genome sequence of ${it D. grandis}$ will be useful for elucidating the common principles of the radioresistance based on the extremely efficient DNA repair mechanisms in Deinococcus species by the comparative analysis of genomic sequences.

論文

Draft genome sequence of ${it Methylobacterium}$ sp. ME121, isolated from soil as a mixed single colony with ${it Kaistia}$ sp. 32K

藤浪 俊*; 武田 喜代子*; 小野寺 威文*; 佐藤 勝也; 清水 哲*; 若林 佑*; 鳴海 一成*; 中村 顕*; 伊藤 政博*

Genome Announcements (Internet), 3(5), p.e01005-15_1 - e01005-15_2, 2015/09

https://doi.org/10.1128/genomeA.01005-15

${it Methylobacterium}$ sp. ME121 was isolated from soil as a mixed single colony with ${it Kaistia}$ sp. 32K during our screening of L-glucose-utilizing microorganisms, and its growth was enhanced by coculture. It was expected that genomic analysis of this bacterium would provide novel information on coculture-dependent growth enhancement. The genomic information of symbiotic bacteria could be of use for studying the molecular mechanisms underlying microbial symbiosis. The draft genome sequence of ${it Methylobacterium}$sp. ME121 is 7,096,979 bp in total length and comprises 197 large contigs ($$>$$ 500 bp) that was deposited at DDBJ/EMBL/GenBank under the accession number BBUX00000000. The draft genome sequence shows that ${it Methylobacterium}$ sp. ME121 has some genes that encode putative methanol/ethanol family PQQ-dependent dehydrogenases involved in methylotrophy. Some unknown factor provided by the coculture may contribute to increase the growth of ${it Methylobacterium}$ sp. ME121.

論文

Draft genome sequence of calcium-dependent ${it Paenibacillus}$ sp. strain TCA20, isolated from a hot spring containing a high concentration of calcium ions

藤浪 俊*; 武田 喜代子*; 小野寺 威文*; 佐藤 勝也; 佐野 元彦*; 高橋 優嘉*; 鳴海 一成*; 伊藤 政博*

Genome Announcements (Internet), 2(5), p.e00866-14_1 - e00866-14_2, 2014/09

https://doi.org/10.1128/genomeA.00866-14

Calcium-dependent ${it Paenibacillus}$ sp. strain TCA20 was isolated from a water sample of a hot spring containing a high concentration of calcium ions. Here, we report the draft genome sequence of this bacterium, which may be the basis for the research of calcium ion homeostasis. The draft genome sequence of ${it Paenibacillus}$ sp. strain TCA20 totals 5,631,463 bp in length and is composed of 33 large contigs ($$>$$ 500 bp) that was deposited at DDBJ/EMBL/Genbank under the accession no. BBIW00000000. The annotation of the draft genome sequence shows that ${it Paenibacillus}$ sp. strain TCA20 has a calcium-specific calcium/proton antiporter, ChaA, and a P-type calcium-transporting ATPase, YloB, was identified as calcium transporters. These transporters may also be important for the growth of ${it Paenibacillus}$ sp. strain TCA20 under the high concentration of calcium ions.

論文

Draft genome sequence of potassium-dependent alkaliphilic ${it Bacillus}$ sp. strain TS-2, isolated from a jumping spider

藤浪 俊*; 武田 喜代子*; 小野寺 威文*; 佐藤 勝也; 佐野 元彦*; 鳴海 一成*; 伊藤 政博*

Genome Announcements (Internet), 2(3), p.e00458-14_1 - e00458-14_2, 2014/05

https://doi.org/10.1128/genomeA.00458-14

The potassium-dependent alkaliphilic ${it Bacillus}$ sp. strain TS-2 was isolated from the mashed extract of a jumping spider, and its draft genome sequence was obtained. Comparative genomic analysis with a previously sequenced sodium-dependent alkaliphilic ${it Bacillus}$ species may reveal potassium-dependent alkaline adaptation mechanisms. The draft genome sequence of ${it Bacillus}$ sp. strain TS-2 was 4,360,646 bp in total length, comprised 58 large contigs ($$>$$ 500 bp) that was deposited at DDBJ/EMBL/Genbank under the accession number BAWL00000000. In the draft genome sequence of ${it Bacillus}$ sp. strain TS-2, two sets of ${it mrp}$ genes, which encode multisubunit secondary cation/proton antiporter-3 family proteins, were annotated. The Mrp complex acts as an Na$$^{+}$$/H$$^{+}$$ antiporter in typical alkaliphilic ${it Bacillus}$ species and plays a critical role in the sodium-dependent alkaline adaptation mechanism.

論文

Genetic analysis of novel DNA cross-link repair genes common to ${it Deinococcus}$ and ${it Thermus}$

小野寺 威文*; 佐藤 勝也; 太田 敏博*; 鳴海 一成*

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 111, 2014/03

The ${it ygjD}$ and ${it yeaZ}$ orthologs are highly conserved in eubacteria, and the former is also widely found in the genomes of archaea and eukaryotes. However, their functions are still poorly understood. ${it Deinococcus radiodurans}$ and ${it Thermus thermophilus}$ possess the both orthologs hereafter ${it DrygjD}$, ${it DryeaZ}$, ${it TtygjD}$ and ${it TtyeaZ}$, respectively. We have reported that the ${it DrygjD}$ and ${it DryeaZ}$ disruptants show extreme sensitivity to mitomycin C (MMC), which causes interstrand DNA cross-links. In this study, we constructed ${it TtygjD}$ and ${it TtyeaZ}$ gene expression plasmids and the resultant plasmids were introduced into the ${it DrygjD}$ and ${it DryeaZ}$ disruptant strains. To investigate whether ${it ygjD}$ and ${it yeaZ}$ orthologs share the common function in ${it D. radiodurans}$ and ${it T. thermophilus}$, these generated strains were challenged by MMC.

論文

Role of DNA repair and effect of herbal extract on LOH induced by ion beam radiations in ${it Saccharomyces cerevisiae}$

布柴 達男*; 坂田 弥生*; 山内 理子*; 佐藤 勝也; 小野寺 威文*; 鳴海 一成*

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 118, 2014/03

The LOH (loss of heterozygosity) induction by various ion beam radiations was investigated in diploid ${it Saccharomyces cerevisiae}$. The ion beams $$^{12}$$C$$^{5+}$$, $$^{12}$$C$$^{6+}$$, $$^{4}$$He$$^{2+}$$ and $$^{40}$$Ar$$^{13+}$$ at the lowest dose (75, 75, 200 and 150 Gy, respectively), which had 30$$sim$$50% lethality, induced LOH with 10-fold higher frequency. The LOH induction was predominantly ($$sim$$ 90%) resulted from homologous recombination. Pol$$zeta$$ may be involved in the induction of LOH by ion beam radiations, because in the strain lacking Rev3, only slight induction of LOH was observed. In addition, the effects of 14 herbal extracts were examined on iron-beam radiation induced LOH, and ethanol extract of ${it Eucalyptus regnans}$ possessed inhibitory effect on LOH induced by $$^{12}$$C$$^{5+}$$ ion-beam radiation with the manner dependent on doses of extract.

論文

Mutagenic effect of carbon ion beams in ${it Deinococcus radiodurans}$

佐藤 勝也; 小野寺 威文*; 武田 喜代子; 鳴海 一成*

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 110, 2014/03

In this study, we investigated mutant frequencies of two different antibiotic-resistant mutants for carbon ion beams in ${it Deinococcus radiodurans}$ and identified the mutation sites in the streptomycin-resistant (Sm$$^{rm R}$$) mutants. The Sm$$^{rm R}$$ mutant frequencies increased depending on radiation dose. It seems that this dose range is the best dose to generate the mutants of interest for research and breeding purpose. Four kinds of mutation sites at the ${it rpsL}$ locus were determined from 8 Sm$$^{rm R}$$ mutants. These mutations cause amino acid substitutions at position 43 (Lys to Thr or Arg) and 88 (Lys to Glu or Arg) in the S12 protein, respectively. The two hot spots at Lys43 and Lys88 in the S12 protein might be a binding target of streptomycin or adjacent to the center of streptomycin interaction with the ribosome.

論文

Draft genome sequence of sodium-independent alkaliphilic ${it Microbacterium}$ sp. strain TS-1

藤浪 俊*; 武田 喜代子; 小野寺 威文*; 佐藤 勝也; 佐野 元彦*; 鳴海 一成*; 伊藤 政博*

Genome Announcements (Internet), 1(6), P. e01043-13, 2013/12

https://doi.org/10.1128/genomeA.01043-13

Alkaliphilic ${it Microbacterium}$ sp. strain TS-1, newly isolated from the jumping spider, showed Na$$^{+}$$-independent growth and motility. Here, we report the draft genome sequence of this bacterium, which may provide beneficial information for Na$$^{+}$$-independent alkaline adaptation mechanisms. The draft genome sequence of ${it Microbacterium}$ sp. strain TS-1 was 3,396,165 bp in total length and comprised 3 large contigs (2,699,404 bp, 691,278 bp, and 5,483 bp) that was deposited at DDBJ/ EMBL/GenBank under the accession number BASQ00000000. The annotation of the draft genome sequence indicated that this bacterium has 3 sets of ${it mrp}$ genes, which encode multisubunit secondary cation/proton antiporter-3 family proteins for pH homeostasis. The annotation also indicated that this bacterium has genes involved in chemotaxis/flagellar components, including one set of ${it mot}$ genes.

論文

${it Deinococcus radiodurans}$ YgjD and YeaZ are involved in the repair of DNA cross-links

小野寺 威文; 佐藤 勝也; 太田 敏博*; 鳴海 一成

Extremophiles, 17(1), p.171 - 179, 2013/01

https://doi.org/10.1007/s00792-012-0506-4
 被引用回数：10 パーセンタイル：25.55(Biochemistry & Molecular Biology)

Orthologs of ${it Escherichia coli ygjD}$ and ${it yeaZ}$ genes are highly conserved in various organisms. The genome of the radioresistant bacterium ${it Deinococcus radiodurans}$ possesses single orthologs of ${it ygjD}$ (DR_0382) and ${it yeaZ}$ (DR_0756). Complete loss of either one or both genes did not result in any significant changes in cell growth efficiency, indicating that both genes are not essential for cell viability in ${it D. radiodurans}$, unlike the case with other species such as ${it E. coli}$, ${it Bacillus subtilis}$ and ${it Saccharomyces cerevisiae}$. Survival rates following DNA damage induced by hydrogen peroxide, $$N$$-methyl-$$N'$$-nitro-$$N$$-nitrosoguanidine, ultra violet radiation, $$gamma$$-rays, cisplatin and mitomycin C (MMC) were compared among the wild-type strain and ${it D. radiodurans ygjD}$/${it yeaZ}$ null mutants. Interestingly, the null mutants exhibited high sensitivity to MMC, which mainly causes interstrand DNA cross-links. The sensitivity of the null mutants to MMC was restored to that of the wild-type by transformation with plasmids expressing these genes. These results suggest that ${it D. radiodurans ygjD}$ and ${it yeaZ}$ genes are involved in DNA repair and play a role in the repair of DNA cross-links in ${it D. radiodurans}$.

論文

Analysis of mutant frequencies for different LET radiations in ${it Deinococcus radiodurans}$

佐藤 勝也; 手島 光平*; 小野寺 威文; 鳴海 一成

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 103, 2013/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2012-046.pdf

${it Deinococcus radiodurans}$ exhibits extraordinary resistance to the lethal effects of ionizing radiations. This resistance has been attributed to its highly proficient DNA repair capacity. In this study, we investigated antibiotics-resistant mutant frequencies for different LET radiations in ${it D. radiodurans}$. Rifampicin is one of the antibiotics that inhibit RNA synthesis by directly interacting with the RNA polymerase beta subunit protein encoded by ${it rpoB}$ gene. By genetically altering the ${it rpoB}$ gene in genome, Rif$$^{R}$$ mutant can be generated. The Rif$$^{R}$$ mutant frequencies increased depending on radiation dose. The highest Rif$$^{R}$$ mutant frequencies were observed at a dose range that give 10$$^{-1}$$ to 10$$^{-2}$$ of surviving fraction. There is the possibility that this dose range is the best dose to generate the mutants of interest for research and breeding purposes.

論文

Functional analysis of universally conserved genes, ${it ygjD}$ and ${it yeaZ}$ orthologs, in DNA repair of ${it Deinococcus radiodurans}$

小野寺 威文; 佐藤 勝也; 太田 敏博*; 鳴海 一成

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 104, 2013/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2012-046.pdf

The ${it ygjD}$ and ${it yeaZ}$ orthologs are highly conserved in eubacteria, and the former is also widely found in the genomes of archaea and eukaryotes. ${it D. radiodurans}$, well known as a radioresistant bacterium, possesses the both orthologs, hereafter ${it DrygjD}$ and ${it DryeaZ}$. In this study, we successfully constructed ${it DrygjD}$ disruptant, ${it DryeaZ}$ disruptant and ${it DrygjD DryeaZ}$ double-disruptant strains. This result clearly indicated that neither ${it DrygjD}$ nor ${it DryeaZ}$ genes is essential for cell viability in ${it D. radiodurans}$. These gene disruptant strains exhibited extreme sensitivity to mitomycin-C compare to the wild-type strain. The deficiency of ${it DrygjD}$ and ${it DryeaZ}$ genes was complemented to restore the wild-type phenotype by introducing plasmids that express these genes.

論文

出芽酵母ゲノム健常性に対するイオンビーム照射効果

布柴 達男*; 平澤 佑啓*; 山内 理子*; 佐藤 勝也; 手島 光平*; 小野寺 威文; 鳴海 一成

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 111, 2013/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2012-046.pdf

The LOH (loss of heterozygosity) induction by various ion beam radiations was investigated in diploid ${it Saccharomyces cerevisiae}$. The ion beams $$^{12}$$C$$^{5+}$$, $$^{12}$$C$$^{6+}$$, $$^{4}$$He$$^{2+}$$ and $$^{40}$$Ar$$^{13+}$$ at the lowest dose (75, 75, 200 and 150 Gy, respectively), which had 30-50% lethality, induced LOH with 10-fold higher frequency. The LOH induction was predominantly ($$sim$$90%) resulted from gene conversion or crossover through homologous recombination, and followed by chromosome loss through chromosome mis-segregation. Induction of LOH by $$^{12}$$C$$^{5+}$$ was also examined in ${it S. cerevisiae}$ deficient in AP endonuclease (Apn1), translesion DNA polymerases Pol$$eta$$ encoded by Rad30 and Pol$$zeta$$ encoded by Rev3 and Rev7. Pol$$zeta$$ may be involved in the induction of LOH, because a slight induction of LOH by $$^{12}$$C$$^{5+}$$ was observed in the Rev3-deficient strain.

論文

The Role of ${it Deinococcus radiodurans}$ RecFOR proteins in homologous recombination

佐藤 勝也; 菊地 正博; Ishaque, A. M.*; 大庭 寛史*; 山田 貢; 手島 光平; 小野寺 威文; 鳴海 一成

DNA Repair, 11(4), p.410 - 418, 2012/04

https://doi.org/10.1016/j.dnarep.2012.01.008
 被引用回数：26 パーセンタイル：59.44(Genetics & Heredity)

放射線抵抗性細菌の相同組換え機構におけるRecFORタンパク質の役割を明らかにするために、${it recF}$, ${it recO}$及び${it recR}$遺伝子破壊株を作製し、分子遺伝学及び分子生物学的解析を行った。${it recR}$遺伝子破壊株では、形質転換効率の著しい低下が見られたことから、RecRタンパク質は、細胞内に取り込んだ外来DNAの安定性に関与していることがわかった。また、${it recF}$遺伝子破壊株は、他の遺伝子破壊株に比べて、$$gamma$$線,紫外線及びマイトマイシンCに非常に感受性を示した。これらの高い感受性は、RecFタンパク質が、組換え修復タンパク質RecAの活性化に重要な役割を担っていることに起因していることがわかった。以上のことから、放射線抵抗性細菌の効率的なDNA鎖切断修復を担うextended synthesis-dependent strand annealing(伸長合成依存的DNA鎖対合)経路の初期段階として、RecF及びRecRタンパク質は、RecAタンパク質の活性化とDNAの安定性にそれぞれ関与していることを明らかにした。

論文

Lethal effects of different LET radiations in gene disruptant strain of ${it Deinococcus radiodurans}$

佐藤 勝也; 手島 光平; 小野寺 威文; 鳴海 一成

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 106, 2012/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2011-043.pdf

In this study, we investigated lethal effects of different LET radiations in ${it recA}$ and ${it pprA}$ gene disruptant strains and determined the relationship between LET and RBE. In both gene disruptant strains, radiosensitivities to four kinds of ion beams ($$^{4}$$He$$^{2+}$$, $$^{12}$$C$$^{6+}$$, $$^{12}$$C$$^{5+}$$ and $$^{20}$$Ne$$^{8+}$$) were almost equal to that of the $$gamma$$ rays. Both gene disruptant strains did not exhibit the dependence of LET on RBE at range of LET from about 0.2 to 441 keV/$$mu$$m. These results indicate that RecA-mediated HR and PprA-mediated NHEJ mechanisms in ${it Deinococcus radiodurans}$ play important roles in repairing the ion beams-induced clustered damage as well as the $$gamma$$ ray-induced damage.

論文

Involvement of universal conserved genes, ${it ygjD}$ and ${it yeaZ}$ orthologs, in DNA repair of ${it Deinococcus radiodurans}$

小野寺 威文; 佐藤 勝也; 鳴海 一成; 太田 敏博*

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 107, 2012/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2011-043.pdf

In this study, we generated ${it DrygjD}$ and ${it DryeaZ}$ disruptant strains and investigated the disruption effect to DNA damaging agents in an effort to gain insight into the role of DrygjD and DryeaZ proteins in ${it Deinococcus radiodurans}$. We successfully constructed ${it DrygjD}$ disruptant, ${it DryeaZ}$ disruptant and ${it DrygjD DryeaZ}$ double-disruptant strains. All the disruptant strains did not exhibit the delayed growth compared to the wild-type strain, clearly indicating that neither DrygjD nor DryeaZ protein is essential for cell viability. These gene disruptant strains exhibited extremely sensitivity to mitomycin C (MMC), which causes inter- and intrastrand DNA crosslinking, suggesting that DrygjD and DryeaZ proteins are involved in the DNA repair mechanism and especially play a critical role in MMC-induced DNA damage in ${it D. radiodurans}$.

論文

放射線抵抗性細菌

小野寺 威文; 鳴海 一成

日本微生物生態学会誌, 26(2), p.75 - 77, 2011/09

https://doi.org/10.20709/jsmeja.26.2_75

イオンビーム変異誘発研究グループでは、放射線抵抗性細菌の代表選手である${it D. radiodurans}$の著しく高い放射線耐性の原因を解明する研究に携わってきた。2011年3月の東京電力福島第一原子力発電所の事故により放出された放射性物質が表層土壌に降下した。表層土や汚泥に含まれる主たる放射性核種はセシウムである。セシウムは土壌に強く吸着しているので、今後の放射性物質の除染の必要性を考えた場合、表層土や汚泥からセシウムを選択的に取り出す技術の確立が急務とされている。このような土の除染対策に微生物を直接利用することは現実的ではないにせよ、大量の放射性廃棄物を別途保管しなければならないことを考えると、土からセシウムを回収する何らかの技術が確立された後、二次的にセシウムを濃縮・回収し、保管する放射性廃棄物の量をなるべく減らすことが必要となってくる。この二次的なセシウム濃縮に微生物を利用することを、さまざまな方法の中の選択肢のひとつとして考えることは可能であろう。二次濃縮ともなれば、被曝量は微生物の致死線量には至らずとも、突然変異を高頻度に誘発することになる。濃縮効率,低コスト,安全性などを勘案すると、放射線抵抗性細菌は、二次的な放射性セシウム濃縮のための宿主として有望かも知れないと考えている。

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出芽酵母におけるゲノム安定化に対するイオンビームの影響

布柴 達男*; 平澤 佑啓*; 山内 理子*; 坂田 弥生*; 相原 玲子*; 佐藤 勝也; 手島 光平; 小野寺 威文; 鳴海 一成

no journal, , 

出芽酵母は1倍体と2倍体の両方を用いることができることから、ヘテロ接合性喪失(LOH: loss of heterozygosity)を指標とすることができる。われわれは既に突然変異マーカー遺伝子${it CAN1}$の一方のアレルに変異を持つ2倍体細胞を構築し、LOH検出系を樹立した。本研究ではこの系を用い、イオンビームによって出芽酵母のゲノムやゲノム維持機構への影響に関する基礎的知見を得ることとともに、DNA修復や損傷乗り越えDNA合成酵素の役割についても検討した。解析の結果、いずれの核種も致死作用、LOH誘発性にそれほど大きな差は見られなかった。また、イオンビーム照射が染色体不均等分配を引き起こす可能性は確認できなかった。さらに、Pol$$zeta$$(Rev3)欠損株ではLOH誘発頻度の照射による上昇率が低く、LOH誘発にtranslesion DNA polymerase Pol$$zeta$$の関与が伺えた。

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${it Deinococcus}$と${it Thermus}$に共通する新規DNA鎖間架橋修復遺伝子の遺伝学的解析

小野寺 威文; 中村 顕*; 佐藤 勝也; 太田 敏博*; 鳴海 一成

no journal, , 

これまでに、放射線抵抗性細菌${it Deinococcus radiodurans}$と高度好熱菌${it Thermus thermophilus}$の${it ygjD}$,${it yeaZ}$オルソログである${it DrygjD}$, ${it DryeaZ}$及び${it TtygjD}$, ${it TtyeaZ}$遺伝子破壊株作製に成功したこと、これらの遺伝子破壊株がDNA架橋剤であるmitomycin C (MMC)に対して著しい感受性を示すことを報告してきた。当該遺伝子は、${it D. radiodurans}$及び${it T. thermophilus}$の増殖に必須ではなく、さらにDNA修復に関連する新規の遺伝子である可能性が見いだされた。本研究では、${it DrygjD}$及び${it DryeaZ}$遺伝子破壊株のMMCに対する感受性が当該遺伝子の機能欠損に起因することを確かめるために、野生型の${it DrYgjD}$及び${it DrYeaZ}$発現プラスミドを各遺伝子破壊株に導入して遺伝子相補試験を行った。また、${it ygjD}$, ${it yeaZ}$オルソログの機能は生物間で共通しているかを調べるために、${it TtYgjD}$と${it TtYeaZ}$発現プラスミドを${it DrygjD}$及び${it DryeaZ}$遺伝子破壊株に導入してMMCに対する生存率を測定することで、生物間における${it ygjD}$及び${it yeaZ}$オルソログの機能共通性を解析したので報告する。

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放射線抵抗性細菌の相同組換え機構におけるRecFORタンパク質の重要性

佐藤 勝也; 菊地 正博; 大庭 寛史*; 山田 貢; 手島 光平; 小野寺 威文; 鳴海 一成

no journal, , 

放射線抵抗性細菌の相同組換え機構におけるRecFORタンパク質の役割を明らかにするために、RecF, RecO及びRecR欠損株を作製し、分子遺伝学及び分子生物学的解析を行った。欠損株の$$gamma$$線,紫外線及びマイトマイシンCの各変異原に対する耐性は、いずれもRecF欠損株$$<$$RecO欠損株$$<$$RecR欠損株の順であった。このことは、各変異原によって誘発されるDNA損傷の修復には、RecFORの中でRecFタンパク質の機能が最重要であることを示している。また、欠損株における遺伝子交換反応の頻度は、RecF欠損株$$>$$RecO欠損株$$>$$RecR欠損株の順であった。このことから、遺伝子交換反応には、RecFORの中でRecRタンパク質の機能が最重要であることがわかった。以上の結果から、DNAに損傷がある場合の相同組換えとDNAに損傷がない場合の相同組換えではRecFタンパク質とRecRタンパク質の重要度が逆転しており、それぞれの反応で相同組換えのメカニズムが異なるということを明らかにした。

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New host-vector system for ${it Deinococcus geothermalis}$

鳴海 一成; 小野寺 威文; 佐藤 勝也

no journal, , 

${it Deinococcus geothermalis}$ DSM11300 is an extremely radiation resistant, moderately thermophilic bacterium closely related to the mesophilic ${it Deinococcus radiodurans}$. It has been reported that the ${it D. geothermalis}$ genome was comprised of a chromosome (2.47 Mb) and two plasmids (574 kb and 206 kb). In this study, we discovered that the ${it D. geothermalis}$ genome contained a small cryptic plasmid pGEC1 (1,957 bp) that had not been reported so far. pGEC1 possessed two open reading frames, one encoding 78 amino acid residues (pGEC Orf1) and the other encoding 298 amino acid residues (pGEC Orf2). The predicted amino acid sequence encoded by pGEC Orf1 exhibited similarity to the N-terminal region of hypothetical proteins upstream of the replication initiation factor encoded by plasmids of ${it Shewanella}$ species. On the other hand, the predicted amino acid sequence encoded by pGEC1 Orf2 exhibited weak homology to replication initiation factors encoded by plasmids of thermophilic ${it Bacillus}$ sp. TK015 and ${it Synechocystis}$ sp. PCC6803.

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