In VivoCharacterization of the Unorthodox BvgS Two-component Sensor Protein ofBordetella pertussis

• Published in: Journal of molecular biology Vol. 248; no. 3; pp. 596 - 610
• Main Authors: Beier, Dagmar, Schwarz, Brigitte, Fuchs, Thilo M., Gross, Roy
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.1995
• Subjects: Bordetella; sensor protein; signal transduction; two-component system; virulence regulation; Bordetella; sensor protein; signal transduction; two-component system; virulence regulation
• ISSN: 0022-2836; 1089-8638
• 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 ofBordetella pertussishave 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 analysisin 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 theB. pertussischromosome. However, some of these mutants could be complemented to the wild-type phenotype by the separate expression of various C-terminal BvgS domainsin transindicating a direct interaction of the truncated and complete BvgS proteins. Therefore, the dimerization capacity of the cytoplasmic BvgS domains was analysed using a λ 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.