background and objectives: brucella, causative of brucellosis, has some potential virulence factors involved in brucella replication and its strategies to circumvent the immune response. one of them is the virb gene that encodes the type іv secretion system proteins (t4ss) involved in intracellular replication of organism. brucella virulence factor a ( bvf a), and urease ( ure ) has also been d...

BACKGROUND AND OBJECTIVES Brucella, causative of brucellosis, has some potential virulence factors involved in Brucella replication and its strategies to circumvent the immune response. One of them is the virB gene that encodes the type IV secretion system proteins (T4SS) involved in intracellular replication of organism. Brucella virulence factor A (bvfA), and urease (ure) has also been descri...

Brucellosis is a widespread zoonotic disease causing considerable economic and public health problems. Despite animal vaccination, brucellosis remains endemic in some areas such as Iran, especially in the western Iranian province of Hamadan. We sought to detect some of the most common virulence-associated genes in Brucella isolated from human blood cultures to determine the prevalence of some v...

VirB activates transcription of virulence genes in Shigella flexneri by alleviating heat-stable nucleoid-structuring protein-mediated promoter repression. VirB is unrelated to the conventional transcriptional regulators, but homologous to the plasmid partitioning proteins. We determined the crystal structures of VirB HTH domain bound by the cis-acting site containing the inverted repeat, reveal...

BACKGROUND Brucella melitensis is a facultative, intracellular, pathogenic bacterium that replicates within macrophages. The type IV secretion system encoded by the virB operon (virB) is involved in Brucella intracellular survival. However, the underlying molecular mechanisms, especially the target proteins affected by the virB, remain largely unclear. METHODOLOGY/PRINCIPAL FINDINGS In order ...

Transcription of the virB gene, a transcriptional regulator of invasion genes on the large plasmid of Shigella flexneri, is strictly regulated by growth temperature; when bacteria are grown at 37 degrees C, virB transcription is highly activated, while at 30 degrees C the level of virB transcription decreases to less than 5% of that at 37 degrees C. Transcription from the virB promoter is activ...

The type IV secretion system encoded by the virB operon is required for full virulence of Brucella sp., and the present study links the RNA chaperone Hfq to wild-type expression of virB in Brucella abortus 2308. Studies employing virB-lacZ fusions, quantitative reverse transcription-PCR, and immunoblot analysis showed that both transcription and translation of virB are decreased in an isogenic ...

Type IV secretion is used by pathogenic microorganisms to transfer effector macromolecules to eukaryotic target cells. The VirB/D4 apparatus of Agrobacterium tumefaciens transfers DNA and proteins to plant cells. We postulated that the cell pole is the site of assembly of the A. tumefaciens type IV apparatus. Using immunofluorescence microscopy, we now demonstrate that 10 of the VirB proteins l...

Agrobacterium tumefaciens is a Gram-negative plant-pathogenic bacterium that causes crown gall disease by transferring and integrating its transferred DNA (T-DNA) into the host genome. We characterized the chromosomally encoded alpha-crystallin-type small heat-shock protein (alpha-Hsp) HspL, which was induced by the virulence (vir) gene inducer acetosyringone (AS). The transcription of hspL but...

brucellosis is a widespread zoonotic disease causing considerable economic and public health problems. despite animal vaccination, brucellosis remains endemic in some areas such as iran, especially in the western iranian province of hamadan. we sought to detect some of the most common virulence-associated genes in brucella isolated from human blood cultures to determine the prevalence of some v...