極限環境微生物学会誌
Online ISSN : 1881-5758
Print ISSN : 1348-5474
ISSN-L : 1348-5474
4 巻 , 1 号
選択された号の論文の3件中1~3を表示しています
巻頭言
原著論文
  • N Hirota, T Matsuo, A Ikeda, R Yatsunami, T Fukui, S Nakamura
    2005 年 4 巻 1 号 p. 14-24
    発行日: 2005年
    公開日: 2007/02/23
    ジャーナル フリー
    The ferredoxin (Fd) from Haloarcula japonica possesses a plant-type [2Fe-2S] cluster and is stable at high salt concentrations. Ha. japonica Fd (HjFd) includes an N-terminal additional domain rich in acidic amino acids, as well as a common core domain that contains the Fe-S cluster. The N-terminally HAT-tagged intact HjFd (HAT/HjFd) and spinach/Ha. japonica chimeric Fd (HAT/Sp/HjFd) were prepared and characterized. Escherichia coli-produced HAT/Sp/HjFd and Ha. japonica-produced HAT/HjFd were produced as holoproteins. On the other hand, E. coli-produced HAT/HjFd did not incorporate the Fe-S cluster. These results suggested that the N-terminal domain of HjFd contributed to the polypeptide folding and successive Fe-S cluster incorporation under high salt conditions. Both Ha. japonica-produced HAT/HjFd and E. coli-produced HAT/Sp/HjFd were stable at high salt concentrations (≥1.5 M NaCl), although a reduction in stability was observed at lower concentrations. Lack of the N-terminal domain did not affect the stability of HjFd, indicating that the core domain mainly contributed to the stability of HjFd at high salt concentrations. Solubility of E. coli-produced HAT/Sp/HjFd under high salt conditions was significantly lower than that of Ha. japonica-produced HAT/HjFd. It was revealed that substitution of the N-terminal domain of HjFd to that of spinach Fd injured the solubility of HjFd. Thus, it was concluded that the N-terminal domain of HjFd should perform the essential functions for halophilic adaptation from the folding process through the folded state.
  • H Tamegai, S Nakamura, M Miyazaki, Y Nogi, R Kasahara, C Kato, K Horik ...
    2005 年 4 巻 1 号 p. 25-31
    発行日: 2005年
    公開日: 2007/02/23
    ジャーナル フリー
    In the present study, we investigated the physiological properties of Pseudomonas sp. strain MT-1 isolated from the mud of Mariana Trench. Strain MT-1 was closely related with members of the genus Pseudomonas, especially with Pseudomonas chloritidismutans and Pseudomonas stutzeri on the basis of 16S rDNA sequence. The DNA-DNA hybridization values between strain MT-1 and Pseudomonas reference strains were significantly lower than those accepted as the phylogenetic definition of a species. MT-1 had polar flagellum, and was facultative anaerobe. The growth occurred in an NaCl concentration of about 0-10% (optimum: 1-2%), in pH of about 6-10 (optimum: 7-8), and in temperature of about 4-45 °C (optimum: 32-35 °C). The G+C content of the DNA was 60.5% mol%. The major quinone was ubiquinone-9. The major fatty acid in strain MT-1 was C16:0 (hexadecanoic acid), C16:1 (hexadecenoic acid) and C18:1 (octadecenoic acid). The organism showed adaptational properties to deep-sea environment compared with the reference strains.
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