Two-Component Systems in Haemophilus influenzae: a Regulatory Role for ArcA in Serum Resistance
AUTOR(ES)
De Souza-Hart, J. A.
FONTE
American Society for Microbiology
RESUMO
Knockout mutations were constructed in the arcA gene of a virulent type b strain of Haemophilus influenzae, and the behavior of the resulting mutants was investigated in a number of conditions that mimicked distinct steps in the natural infection pathway. In arcA mutants, synthesis of capsule and lipooligosaccharide (LOS) and growth in synthetic media were unaltered compared to synthesis of capsule and LOS and growth in synthetic media in the wild-type H. influenzae type b parent strain. However, the virulence of the arcA mutants for BALB/c mice was significantly reduced. Upon exposure to human blood or serum, the arcA mutants showed markedly reduced survival compared with the survival of its wild-type parent. Serum resistance could be fully restored by complementation in cis with the H. influenzae arcA gene but not by complementation in cis with the homologous gene from Escherichia coli. The proteomes of wild-type and mutant bacteria were markedly different, especially under anaerobic conditions, underscoring the global regulatory role of ArcAB in H. influenzae. Evaluation of antibody titers and classical complement activities in various serum samples pointed to complement-mediated bactericidal activity as the factor that distinguishes between the arcA mutant and wild-type phenotypes. Comparative analysis of the membrane fractions of the arcA mutants and the wild-type strain revealed several ArcA-regulated proteins, some of which may be implicated in the serum hypersensitivity phenotype.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=143216Documentos Relacionados
- Role of the two-component signal transduction and the phosphoenolpyruvate: carbohydrate phosphotransferase systems in competence development of Haemophilus influenzae Rd.
- Role of Two Novel Two-Component Regulatory Systems in Development and Phosphatase Expression in Myxococcus xanthus
- Transcriptional control mediated by the ArcA two-component response regulator protein of Escherichia coli: characterization of DNA binding at target promoters.
- Two-component regulatory systems can interact to process multiple environmental signals.
- Comprehensive DNA Microarray Analysis of Bacillus subtilis Two-Component Regulatory Systems