Pi J, Pittard A J
Department of Microbiology, The University of Melbourne, Parkville, Victoria, Australia.
J Bacteriol. 1996 May;178(9):2650-5. doi: 10.1128/jb.178.9.2650-2655.1996.
The PheP protein is a high-affinity phenylalanine-specific permease of the bacterium Escherichia coli. A topological model based on sequence analysis of the putative protein in which PheP has 12 transmembrane segments with both N and C termini located in the cytoplasm had been proposed (J. Pi, P. J. Wookey, and A. J. Pittard, J. Bacteriol. 173:3622-3629, 1991). This topological model of PheP has been further examined by generating protein fusions with alkaline phosphatase. Twenty-five sandwich fusion proteins have been constructed by inserting the 'phoA gene at specific sites within the pheP gene. In general, the PhoA activities of the fusions support a PheP topology model consisting of 12 transmembrane segments with the N and C termini in the cytoplasm. However, alterations to the model, affecting spans III and VI, were indicated by this analysis and were supported by additional site-directed mutagenesis of some of the residues involved.
PheP蛋白是大肠杆菌的一种高亲和力苯丙氨酸特异性通透酶。基于对假定蛋白的序列分析提出了一种拓扑模型，其中PheP有12个跨膜区段，N端和C端均位于细胞质中（J. Pi、P. J. Wookey和A. J. Pittard，《细菌学杂志》173:3622 - 3629，1991年）。通过生成与碱性磷酸酶的蛋白融合体，对PheP的这种拓扑模型进行了进一步研究。通过在pheP基因内的特定位点插入“phoA基因，构建了25个夹心融合蛋白。一般来说，融合体的碱性磷酸酶活性支持一种由12个跨膜区段组成的PheP拓扑模型，其N端和C端位于细胞质中。然而，该分析表明该模型在影响区段III和VI的方面存在改变，并且一些相关残基的额外定点诱变也支持这一点。
