Diagnostic cross-linking of paired cysteine pairs demonstrates homologous structures for two chemoreceptor domains with low sequence identity.
Diagnostic cross-linking of paired cysteine pairs demonstrates homologous structures for two chemoreceptor domains with low sequence identity.
复制标题
成对半胱氨酸对的诊断性交联证明了两个具有低序列同一性的化学感受器结构域的同源结构。
DOI：
10.1110/ps.051802806
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Hazelbauer,GeraldL
中科院分区：
文献类型：
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作者：
Lai,Wing-Cheung;Peach,MeganL;Lybrand,TerryP;Hazelbauer,GeraldL
Hundreds of bacterial chemoreceptors from many species have periplasmic, ligand‐recognition domains of approximately the same size, but little or no sequence identity. The only structure determined is for the periplasmic domain of chemoreceptor Tar fromSalmonellaandEscherichia coli. Do sequence‐divergent but similarly sized chemoreceptor periplasmic domains have related structures? We addressed this issue for the periplasmic domain of chemoreceptor TrgEfromE. coli, which has a low level of sequence similarity to Tar, by combining homology modeling and diagnostic cross‐linking between pairs of introduced cysteines. A homology model of the TrgEdomain was created using the homodimeric, four‐helix bundle structure of the TarSdomain fromSalmonella. In this model, we chose four pairs of positions at which introduced cysteines would be sufficiently close to form disulfides across each of four different helical interfaces. For each pair we chose a second pair, in which one cysteine of the original pair was shifted by one position around the helix and thus would be less favorably placed for disulfide formation. We created genes coding for proteins containing four such pairs of cysteine pairs and investigated disulfide formation in vivo as well as functional consequences of the substitutions and disulfides between neighboring helices. Results of the experimental tests provided strong support for the accuracy of the model, indicating that the TrgEperiplasmic domain is very similar to the TarSdomain. Diagnostic cross‐linking of paired pairs of introduced cysteines could be applied generally as a stringent test of homology models.
