<i>Mycoplasma salivarium</i> におけるヌクレアーゼの存在とその特性  [in Japanese] Existence of the nuclease in <i>Mycoplasma salivarium</i> and its characterization  [in Japanese]

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Author(s)

    • 小川 恵子 Ogawa Keiko
    • 岩手医科大学歯学部口腔生化学講座 Department of Biochemistry, Iwate Medical University School of Dentistry
    • 加茂 政晴 Kamo Masaharu
    • 岩手医科大学歯学部口腔生化学講座 Department of Biochemistry, Iwate Medical University School of Dentistry
    • 水城 春美 Mizuki Harumi
    • 岩手医科大学歯学部口腔外科学第一講座 First Department of Oral and Maxillofacial Surgery, Iwate Medical University School of Dentistry

Abstract

Mycoplasmas depend on the host cells for various nutrients such as nucleic acid precursors and steroids. It has been mentioned that the acquisition of the nucleotides from the host cells is probably mediated through their own nucleases. However, in Mycoplasma salivarium, the existence of nuclease has not yet been known. In this study, we examined the nuclease activity in M. salivarium, and analyzed the properties of the enzyme. The Triton X-114 solubilized supernatant (Tx) obtained from lysate of M. salivarium was used for the enzymatic analysis. The nuclease activity was detected as a specific band of 25kDa by SDS-PAGE and the following in-gel digestion (SDS-PAGE nuclease assay). The nuclease activity of Tx was strictly dependent on Ca^<2+>. The nuclease was heat-stable, and the optimum pH was in the range of 7-9. The nuclease showed a low substrate specificity. From these findings, it was revealed that M. salivarium has a novel type of 25kDa and Ca^<2+> dependent nuclease. Moreover, we examined whether Tx could cleave the chromatin DNA in the nuclei originated from eukaryote cells. Consequently, Tx cleaved the DNA of HS-72 B cell nuclei in vitro. From these results, it has been suggested that M. salivarium in the host cells, obtains nucleotides by the digestion of DNA and RNA from the host cells with their own nuclease, and these cleavage results in injury in host cells and the following various pathogenesis of the oral region.

Mycoplasmas depend on the host cells for various nutrients such as nucleic acid precursors and steroids. It has been mentioned that the acquisition of the nucleotides from the host cells is probably mediated through their own nucleases. However, in <i>Mycoplasma salivarium</i>, the existence of nuclease has not yet been known. <br>In this study, we examined the nuclease activity in <i>M. salivarium</i>, and analyzed the properties of the enzyme. The Triton X-114 solubilized supernatant (Tx) obtained from lysate of <i>M. salivarium</i> was used for the enzymatic analysis. The nuclease activity was detected as a specific band of 25kDa by SDS-PAGE and the following in-gel digestion (SDS-PAGE nuclease assay). The nuclease activity of Tx was strictly dependent on Ca<sup>2+</sup>.The nuclease was heat-stable, and the optimum pH was in the range of 7-9. The nuclease showed a low substrate specificity. From these findings, it was revealed that <i>M. salivarium</i> has a novel type of 25 kDa and Ca<sup>2+</sup> dependent nuclease. <br>Moreover, we examined whether Tx could cleave the chromatin DNA in the nuclei originated from eukaryote cells. Consequently, Tx cleaved the DNA of HS-72 B cell nuclei <i>.in vitro</i>.<br>From these results, it has been suggested that <i>M. salivarium</i> in the host cells, obtains nucleotides by the digestion of DNA and RNA from the host cells with their own nuclease, and these cleavage results in injury in host cells and the following various pathogenesis of the oral region.

Journal

  • Dental Journal of Iwate Medical University

    Dental Journal of Iwate Medical University 33(3), 109-122, 2008

    The Dental Society of Iwate Medical University

References:  45

Cited by:  1

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