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首页> 外文期刊>Journal of bacteriology >A Study of AroP-PheP Chimeric Proteins and Identification of a Residue Involved in Tryptophan Transport
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A Study of AroP-PheP Chimeric Proteins and Identification of a Residue Involved in Tryptophan Transport

机译：AroP-PheP嵌合蛋白的研究和鉴定涉及色氨酸转运的残基

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In vivo recombination has been used to make a series of AroP-PheP chimeric proteins. Analysis of their respective substrate profiles and activities has identified a small region within span III of AroP which can confer on a predominantly PheP protein the ability to transport tryptophan. Site-directed mutagenesis of the AroP-PheP chimera, PheP, and AroP has established that a key residue involved in tryptophan transport is tyrosine at position 103 in AroP. Phenylalanine is the residue at the corresponding position in PheP. The use of PheP-specific antisera has shown that the inability of certain chimeras to transport any of the aromatic amino acids is not a result of instability or a failure to be inserted into the membrane. Site-directed mutagenesis has identified two significant AroP-specific residues, alanine 107 and valine 114, which are the direct cause of loss of transport activity in chimeras such as A152P. These residues replace a glycine and an alanine in PheP and flank a highly conserved glutamate at position 110. Some suggestions are made as to the possible functions of these residues in the tertiary structure of the proteins.
机译：体内重组已用于制备一系列AroP-PheP嵌合蛋白。对它们各自的底物谱和活性的分析已经确定了在AroP的跨度III内的一个小区域，该区域可以赋予主要的PheP蛋白转运色氨酸的能力。 AroP-PheP嵌合体，PheP和AroP的定点诱变已确定，涉及色氨酸运输的关键残基是AroP中103位的酪氨酸。苯丙氨酸是PheP中相应位置的残基。使用PheP特异性抗血清已表明，某些嵌合体无法转运任何芳香族氨基酸不是不稳定或无法插入膜的结果。定点诱变已鉴定出两个重要的AroP特异性残基，丙氨酸107和缬氨酸114，这是在诸如A152P的嵌合体中丧失运输活性的直接原因。这些残基取代了PheP中的甘氨酸和丙氨酸，并在位置110侧接了高度保守的谷氨酸。针对这些残基在蛋白质三级结构中的可能功能提出了一些建议。

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