TAILIEUCHUNG - Báo cáo khoa học: Caenorhabditis elegans expresses a functional ArsA

Because arsenic is the most prevalent environmental toxin, it is imperative that we understand the mechanisms of metalloid detoxification. In prokary-otes, arsenic detoxification is accomplished by chromosomal and plasmid-borne operon-encoded efflux systems. | ễFEBS Journal Caenorhabditis elegans expresses a functional ArsA Yuen-Yi Tseng Chan-Wei Yu and Vivian Hsiu-Chuan Liao Department of BioenvironmentalSystems Engineering NationalTaiwan University Taipei Taiwan Keywords antimonite arsenite ASNA-1 ATPase Caenorhabditis elegans Correspondence V. . Liao Department of BioenvironmentalSystems Engineering NationalTaiwan University no. 1 Roosevelt Road Sec. 4 Taipei 106 Taiwan Fax 886 2 3366 3462 Tel 886 2 3366 5239 E-mail vivianliao@ Received 12 January 2007 revised 12 March 2007 accepted 15 March 2007 doi Because arsenic is the most prevalent environmental toxin it is imperative that we understand the mechanisms of metalloid detoxification. In prokaryotes arsenic detoxification is accomplished by chromosomal and plasmid-borne operon-encoded efflux systems. Bacterial ArsA ATPase is the catalytic component of an oxyanion pump that is responsible for resistance to arsenite As III and antimonite Sb III . Here we describe the identification of a Caenorhabditis elegans homolog asna-1 that encodes the ATPase component of the Escherichia coli As III and Sb III transporter. We evaluated the responses of wild-type and asna-1-mutant nematodes to various metal ions and found that asna-1-mutant nematodes are more sensitive to As III and Sb III toxicity than are wild-type animals. These results provide evidence that ASNA-1 is required for C. elegans defense against As III and Sb III toxicity. A purified maltose-binding protein MBP -ASNA-I fusion protein was biochemically characterized and its properties compared with those of ArsAs. The ATPase activity of the ASNA-1 protein was dependent on the presence of As III or Sb III . As III stimulated ATPase activity by 2 whereas Sb III stimulated it by . The results indicate that As III - and Sb III -stimulated ArsA ATPase activities are not restricted to bacteria but extend to animals by demonstrating that the asna-1 gene .

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