Yamamoto K, Imae Y
Department of Molecular Biology, Faculty of Science, Nagoya University, Japan.
Proc Natl Acad Sci U S A. 1993 Jan 1;90(1):217-21. doi: 10.1073/pnas.90.1.217.
Salmonella typhimurium shows an attractant response to citrate and a repellent response to phenol, and a chemoreceptor mediating these responses has been identified and named Tcp (taxis to citrate and away from phenol). Tcp is one of the methyl-accepting chemotaxis proteins that have a molecular mass of approximately 60 kDa estimated by SDS/PAGE, and its methylation level is increased by citrate and decreased by phenol. Tcp also mediates an attractant response to metal-citrate complexes. The complete nucleotide sequence of the tcp coding region has been determined. The deduced amino acid sequence of Tcp, consisting of 547-amino acid residues, is homologous with that of the aspartate chemoreceptor of S. typhimurium. Thus, Tcp is another member of the bacterial transmembrane chemoreceptor family. Because citrate is a good carbon source for S. typhimurium but is not a carbon source for the closely related species Escherichia coli and because citrate utilization is used as a key diagnostic character to distinguish these species, it is reasonable to assume that Tcp is specific to S. typhimurium.
鼠伤寒沙门氏菌对柠檬酸盐表现出吸引反应，对苯酚表现出排斥反应，并且已经鉴定出介导这些反应的一种化学感受器并将其命名为Tcp（对柠檬酸盐的趋化性和远离苯酚的趋化性）。Tcp是甲基接受趋化蛋白之一，通过SDS/PAGE估计其分子量约为60 kDa，其甲基化水平在柠檬酸盐作用下升高，在苯酚作用下降低。Tcp还介导对金属 - 柠檬酸盐复合物的吸引反应。已经确定了tcp编码区的完整核苷酸序列。推导的由547个氨基酸残基组成的Tcp氨基酸序列与鼠伤寒沙门氏菌天冬氨酸化学感受器的序列同源。因此，Tcp是细菌跨膜化学感受器家族的另一个成员。由于柠檬酸盐是鼠伤寒沙门氏菌的良好碳源，但不是密切相关物种大肠杆菌的碳源，并且由于柠檬酸盐利用被用作区分这些物种的关键诊断特征，因此合理推测Tcp是鼠伤寒沙门氏菌特有的。
