Beier D, Schwarz B, Fuchs T M, Gross R
Lehrstuhl für Mikrobiologie, Theodor-Boveri-Institut für Biowissenschaften (Biozentrum), Universität Würzburg, Germany.
J Mol Biol. 1995 May 5;248(3):596-610. doi: 10.1006/jmbi.1995.0245.
Two-component sensor proteins are typically composed of an amino-acid sensory and a carboxy-terminal transmitter domain containing a kinase activity which catalyses the autophosphorylation of a histidine residue. In a second step, the phosphate is transferred to aspartic acid residues located in the receiver domain of the second component, the response regulator. A few sensor proteins such as the BvgS protein of Bordetella pertussis have a more complex structure. BvgS possesses additional C-terminal domains, including receiver and output modules usually found only in the response regulators. The function of these BvgS domains was investigated by mutation and complementation analysis in vivo. BvgS derivatives were constructed lacking the C-terminal domains or containing mutations in conserved amino acids. All mutations caused the inactivation of BvgS as measured by the expression of virulence factors at the transcriptional and translational level after integration of the mutated alleles in the B. pertussis chromosome. However, some of these mutants could be complemented to the wild-type phenotype by the separate expression of various C-terminal BvgS domains in trans indicating a direct interaction of the truncated and complete BvgS proteins. Therefore, the dimerization capacity of the cytoplasmic BvgS domains was analysed using a lambda repressor based dimerization probe system. These results indicated that BvgS has two dimerization regions, one in the transmitter and a second in the C-terminal receiver/output domains. Furthermore, several BvgS hybrid proteins were constructed which contained substitutions of the BvgS receiver and output domains with similar domains of two-component response regulators and of the sensor protein EvgS. It was found that the receiver domain does not carry BvgS-specific functions and can be exchanged by a heterologous receiver domain. However, the BvgS output domain could not be substituted with output domains of the related proteins without inactivation of BvgS.
双组分传感蛋白通常由一个氨基酸传感结构域和一个羧基末端的传递结构域组成，后者含有一种激酶活性，可催化组氨酸残基的自磷酸化。在第二步中，磷酸基团转移至第二组分（应答调节蛋白）的接收结构域中的天冬氨酸残基上。一些传感蛋白，如百日咳博德特氏菌的BvgS蛋白，具有更为复杂的结构。BvgS拥有额外的C末端结构域，包括通常仅在应答调节蛋白中发现的接收和输出模块。通过体内突变和互补分析研究了这些BvgS结构域的功能。构建了缺失C末端结构域或在保守氨基酸处含有突变的BvgS衍生物。在将突变等位基因整合到百日咳博德特氏菌染色体后，通过转录和翻译水平上毒力因子的表达来衡量，所有突变均导致BvgS失活。然而，其中一些突变体可通过反式单独表达各种C末端BvgS结构域而互补至野生型表型，这表明截短的和完整的BvgS蛋白之间存在直接相互作用。因此，使用基于λ阻遏物的二聚化探针系统分析了细胞质BvgS结构域的二聚化能力。这些结果表明，BvgS有两个二聚化区域，一个在传递结构域，另一个在C末端接收/输出结构域。此外，构建了几种BvgS杂合蛋白，它们用双组分应答调节蛋白和传感蛋白EvgS的相似结构域替换了BvgS的接收和输出结构域。发现接收结构域不具有BvgS特异性功能，可被异源接收结构域替换。然而，BvgS输出结构域不能被相关蛋白的输出结构域替换而不导致BvgS失活。
