允许麦芽糖通过β-半乳糖苷转运系统进行转运的大肠杆菌K-12突变体。
Escherichia coli K-12 mutants that allow transport of maltose via the beta-galactoside transport system.
作者信息
Shuman H A, Beckwith J
出版信息
J Bacteriol. 1979 Jan;137(1):365-73. doi: 10.1128/jb.137.1.365-373.1979.
We have isolated mutants of Escherichia coli that have an altered beta-galactoside transport system. This altered transport system is able to transport a sugar, maltose, that the wild-type beta-galactoside transport system is unable to transport. The mutation that alters the specificity of the transport system is in the lacY gene, and we refer to the allele as lacYmal. The lacYmal allele was detected originally in strains in which the lac genes were fused to the malF gene. Thus, as a result of gene fusion and isolation of the lacYmal mutation, a new transport system was evolved with regulatory properties and specificity similar to those of the original maltose transport system. Maltose transport via the lacYmal gene product is independent of all of the normal maltose transport system components. The altered transport system shows a higher affinity than the wild-type transport system for two normal substrates of the beta-galactoside transport system, thiomethyl-beta-D-galactoside and o-nitrophenyl-beta-D-galactoside.
我们已经分离出了大肠杆菌的突变体，其β-半乳糖苷转运系统发生了改变。这种改变后的转运系统能够转运一种糖——麦芽糖，而野生型β-半乳糖苷转运系统无法转运麦芽糖。改变转运系统特异性的突变位于lacY基因中，我们将该等位基因称为lacYmal。lacYmal等位基因最初是在lac基因与malF基因融合的菌株中检测到的。因此，由于基因融合和lacYmal突变的分离，进化出了一种新的转运系统，其调控特性和特异性与原始麦芽糖转运系统相似。通过lacYmal基因产物进行的麦芽糖转运不依赖于所有正常的麦芽糖转运系统成分。与野生型转运系统相比，改变后的转运系统对β-半乳糖苷转运系统的两种正常底物硫代甲基-β-D-半乳糖苷和邻硝基苯基-β-D-半乳糖苷具有更高的亲和力。
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