Alteration of Na+-coupled transport in site-directed mutants of the melibiose carrier of Escherichia coli

被引：18

作者：

Franco, PJ ^{[1
]}

Wilson, TH ^{[1
]}

机构：

[1] HARVARD UNIV, SCH MED, DEPT CELL BIOL, BOSTON, MA 02115 USA

来源：

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES | 1996年 / 1282卷 / 02期

基金：

美国国家卫生研究院;

关键词：

melibiose carrier; cation cotransport; mutagenesis; (E-coli);

D O I：

10.1016/0005-2736(96)00062-4

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Asn-58 of the Escherichia coli melibiose carrier was replaced by Ala, Leu, Ser, and Gin. Trp-54 was replaced by Leu and a double mutant Leu-54/Ala-58 was constructed using site-directed mutagenesis. Cation/sugar cotransport and sugar-induced cation uptake were studied for each mutant. The change of Asn-58 to Ala results in a nearly complete loss of Na+-stimulated galactoside transport as well as sugar-stimulated Na+ uptake. Substitutions of Leu, Gin, and Ser for Asn-58 were also defective in Na+-stimulated sugar transport. The Trp-54 to Leu mutant shows moderate sugar accumulation with cation selectivity similar to wild-type. The double mutant Leu-54/Ala-58 shows elevated H+-melibiose cotransport as well as reduced Na+-stimulated melibiose cotransport. These results suggest that Asn-58 is important for Na+ recognition.

引用

页码：240 / 248

页数：9

共 33 条

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