The Brucella suis Homologue of the Agrobacterium tumefaciens Chromosomal Virulence Operon chvE Is Essential for Sugar Utilization but Not for Survival in Macrophages
American Society for Microbiology
Brucella strains possess an operon encoding type IV secretion machinery very similar to that coded by the Agrobacterium tumefaciens virB operon. Here we describe cloning of the Brucella suis homologue of the chvE-gguA-gguB operon of A. tumefaciens and characterize the sugar binding protein ChvE (78% identity), which in A. tumefaciens is involved in virulence gene expression. B. suis chvE is upstream of the putative sugar transporter-encoding genes gguA and gguB, also present in A. tumefaciens, but not adjacent to that of a LysR-type transcription regulator. Although results of Southern hybridization experiments suggested that the gene is present in all Brucella strains, the ChvE protein was detected only in B. suis and Brucella canis with A. tumefaciens ChvE-specific antisera, suggesting that chvE genes are differently expressed in different Brucella species. Analysis of cell growth of B. suis and of its chvE or gguA mutants in different media revealed that ChvE exhibited a sugar specificity similar to that of its A. tumefaciens homologue and that both ChvE and GguA were necessary for utilization of these sugars. Murine or human macrophage infections with B. suis chvE and gguA mutants resulted in multiplication similar to that of the wild-type strain, suggesting that virB expression was unaffected. These data indicate that the ChvE and GguA homologous proteins of B. suis are essential for the utilization of certain sugars but are not necessary for survival and replication inside macrophages.
ACESSO AO ARTIGOhttp://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=95417
- The Agrobacterium tumefaciens virulence gene chvE is part of a putative ABC-type sugar transport operon.
- The chromosomal virulence gene, chvE, of Agrobacterium tumefaciens is regulated by a LysR family member.
- Glu-255 outside the predicted ChvE binding site in VirA is crucial for sugar enhancement of acetosyringone perception by Agrobacterium tumefaciens.
- The Phenolic Recognition Profiles of the Agrobacterium tumefaciens VirA Protein Are Broadened by a High Level of the Sugar Binding Protein ChvE
- Early Acidification of Phagosomes Containing Brucella suis Is Essential for Intracellular Survival in Murine Macrophages