KMID : 0880220110490040641
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Journal of Microbiology 2011 Volume.49 No. 4 p.641 ~ p.641
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The ATPase activity of the G2alt gene encoding an aluminium tolerance protein from Anoxybacillus gonensis G2
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Fatih Saban Beris
Lina De Smet Jozef Van Beeumen Hakan Karaoglu SABRIYE CANAKCI Ali Osman Belduz
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Abstract
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The G2ALT gene was cloned and sequenced from the thermophilic bacterium Anoxybacillus gonensis G2. The gene is 666 bp long and encodes a protein 221 amino acids in length. The gene was overexpressed in E. coli and purified to homogeneity and biochemically characterized. The enzyme has a molecular mass of 24.5 kDa and it could be classified as a member of the family of bacterial aluminium resistance proteins based on homology searches. When this fragment was expressed in E. coli, it endowed E. coli with Al tolerance to 500 ¥ìM. The purified G2ALT protein is active at a broad pH range (pH 4.0?10.0) and temperature range (25¡ÆC?80¡ÆC) with optima of 6.0 and the apparent optimal temperature of 73¡ÆC respectively. Under optimal conditions, G2ALT exhibited a low ATPase activity with Km? and Vmax? values of 10¡¾0.55 ¥ìM and 26.81¡¾0.13 mg Pi released/min/mg enzyme, respectively. The ATPase activity of G2ALT requires Mg2+ and Na+ ions, while Zn2+ and Al3+ stimulate the activity. Cd2+ and Ag+ reduced the activity and Li+, Cu2+, and Co2+ inhibited the activity. Known inhibitors of most ATPases, like such as ¥â-mercaptoethanol and ouabain, also inhibited the activity of the G2ALT. These biochemical characterizations suggested that G2ALT belongs to the PP-loop ATPase superfamily and it can be responsible for aluminium tolerance in A. gonensis G2.
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KEYWORD
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aluminium tolerance gene (G2alt), aluminium tolerance protein (G2ALT), ATPase, cloning, aluminium tolerance, Anoxybacillus gonensis G2
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