Functional and biochemical characterization of Escherichia coli sugar efflux transporters
Functional and biochemical characterization of Escherichia coli sugar efflux transporters
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DOI：
10.1074/jbc.274.33.22977
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发表时间：
1999-08-13
影响因子：
4.8
通讯作者：
Olson, ER
中科院分区：
文献类型：
--
作者：
Liu, JY;Miller, PF;Olson, ER
最近已经报道了细菌转运蛋白家族，SET（糖流出转运蛋白）家族（Liu，J.Y.，米勒，P.F.，Gosink，M.，和Olson，E. R.（1999）Mol. Microbiol. 31，1845-1851）。在这项研究中，表征了该家族的三个大肠杆菌成员（SetA、SetB和SetC）的生物化学和细胞生物学特性。我们发现SetA和SetB都可以运输乳糖和葡萄糖。此外，SetA具有广泛的底物特异性，偏好具有烷基或芳基取代基的葡糖苷或半乳糖苷。与观察到的体外底物特异性一致，如通过乳糖操纵子的诱导所测量的，超表达SetA或SetB的菌株对乳糖类似物脱敏。此外，超表达SetA的菌株对生长抑制性糖类似物邻硝基苯基-β-D-硫代半乳糖苷具有抗性。任何一个或所有的一组基因被破坏的菌株是可行的，并没有表现出乳糖利用的缺陷，也没有增加对乳糖操纵子和非代谢糖类似物的诱导剂的敏感性。这些数据表明，在正常的实验室生长条件下，这些基因要么表达很差，要么与其他细胞基因产物冗余。
A family of bacterial transporters, the SET (sugar efflux transporter) family, has been recently reported (Liu, J. Y., Miller, P. F., Gosink, M., and Olson, E. R. (1999) Mol. Microbiol. 31, 1845-1851), In this study, the biochemical and cell biological properties of the three Escherichia coli members (SetA, SetB, and SetC) of the family are characterized. We show that both SetA and SetB can transport lactose and glucose. In addition, SetA has broad substrate specificity, with preferences for glucosides or galactosides with alkyl or aryl substituents, Consistent with the observed in vitro substrate specificities, strains that hyperexpress SetA or SetB are desensitized to lactose analogues as measured by induction of the lac operon, In addition, strains that hyperexpress SetA are resistant to the growth inhibitory sugar analogue o-nitrophenyl-beta-D-thiogalactoside. Strains disrupted for any one or all of the set genes are viable and show no defects in lactose utilization nor increased sensitivity to inducers of the lac operon and nonmetabolizable sugar analogues. The data suggest that the set genes are either poorly expressed under normal laboratory growth conditions or are redundant with other cellular gene products.