Matos M E, Wilson T H
Department of Cell Biology, Harvard Medical School, Boston, MA 02115.
Biochem Biophys Res Commun. 1994 Apr 15;200(1):268-74. doi: 10.1006/bbrc.1994.1444.
A lactose carrier mutant of Escherichia coli (ML308-22) showed a severe defect in thiomethylgalactoside accumulation but a faster than normal entry of o-nitrophenyl-galactoside. Sequencing of the mutant lacY gene revealed a point mutation resulting in the substitution of glycine-159 by a cysteine residue. The mutant showed an increased sensitivity to sulfhydryl reagents, a property that is consistent with the view that the Cysteine-159 is in or near the sugar recognition site and the energy coupling region of the carrier.
大肠杆菌的乳糖载体突变体（ML308 - 22）在硫代甲基半乳糖苷积累方面表现出严重缺陷，但对邻硝基苯 - 半乳糖苷的摄取速度比正常情况快。对突变的lacY基因进行测序发现一个点突变，导致第159位甘氨酸被半胱氨酸残基取代。该突变体对巯基试剂的敏感性增加，这一特性与半胱氨酸 - 159位于载体的糖识别位点或其附近以及能量偶联区域的观点一致。
