Effects of Site-Directed Mutagenesis of Protolytic Residues in Subunit I of Bacillus subtilis aa3-600 Quinol Oxidase. Role of Lysine 304 in Proton Translocation

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• 作者：Gaetano Villani ; Nazzareno Capitanio ; Antonella Bizzoca ; Luigi L. Palese ; Valeria Carlino ; Maria Tattoli ; Philippe Glaser ; Antoine Danchin ; and Sergio Papa
• 刊名：Biochemistry
• 出版年：1999
• 出版时间：February 23, 1999
• 年：1999
• 卷：38
• 期：8
• 页码：2287 - 2294
• 全文大小：229K
• 年卷期：v.38,no.8(February 23, 1999)
• ISSN：1520-4995

文摘

Various protolytic residues in subunit I of aa₃-600 quinol oxidase of the aerobic Gram-positiveBacillus subtilis were mutagenized to nonpolar residues. Two of the mutations, Y284F and K304L, impairedthe bioenergetic function of the microorganism. The Y284F mutation suppressed the electron-transferactivity of quinol oxidase and altered its interaction with CO and H₂O₂, thus showing destruction of thebinuclear domain as observed for the bo₃ quinol oxidase of Escherichia coli. The K304L mutation didnot alter significantly the redox activity of the oxidase and its interaction with CO and H₂O₂ but suppressedthe proton pumping activity of the enzyme. These results show that the K304 residue, which is invariantlyconserved (as K or R) in practically all the sequences of the heme-copper oxidases so far available(around 100), is essential for the proton pumping activity of the oxidase.