TY - JOUR
T1 - Type VI secretion is a major virulence determinant in Burkholderia mallei
AU - Schell, Mark A.
AU - Ulrich, Ricky L.
AU - Ribot, Wilson J.
AU - Brueggemann, Ernst E.
AU - Hines, Harry B.
AU - Chen, Dan
AU - Lipscomb, Lyla
AU - Kim, H. Stanley
AU - Mrázek, Jan
AU - Nierman, William C.
AU - DeShazer, David
PY - 2007/6
Y1 - 2007/6
N2 - Burkholderia mallei is a host-adapted pathogen and a category B biothreat agent. Although the B. mallei VirAG two-component regulatory system is required for virulence in hamsters, the virulence genes it regulates are unknown. Here we show with expression profiling that overexpression of virAG resulted in transcriptional activation of ∼60 genes, including some involved in capsule production, actin-based intracellular motility, and type VI secretion (T6S). The 15 genes encoding the major sugar component of the homopolymeric capsule were up-expressed >2.5-fold, but capsule was still produced in the absence of virAG. Actin tail formation required virAG as well as bimB, bimC and bimE, three previously uncharacterized genes that were activated four- to 15-fold when VirAG was overproduced. Surprisingly, actin polymerization was found to be dispensable for virulence in hamsters. In contrast, genes encoding a T6S system were up-expressed as much as 30-fold and mutations in this T6S gene cluster resulted in strains that were avirulent in hamsters. SDS-PAGE and mass spectrometry demonstrated that BMAA0742 was secreted by the T6S system when virAG was overexpressed. Purified His-tagged BMAA0742 was recognized by glanders antiserum from a horse, a human and mice, indicating that this Hcp-family protein is produced in vivo during infection.
AB - Burkholderia mallei is a host-adapted pathogen and a category B biothreat agent. Although the B. mallei VirAG two-component regulatory system is required for virulence in hamsters, the virulence genes it regulates are unknown. Here we show with expression profiling that overexpression of virAG resulted in transcriptional activation of ∼60 genes, including some involved in capsule production, actin-based intracellular motility, and type VI secretion (T6S). The 15 genes encoding the major sugar component of the homopolymeric capsule were up-expressed >2.5-fold, but capsule was still produced in the absence of virAG. Actin tail formation required virAG as well as bimB, bimC and bimE, three previously uncharacterized genes that were activated four- to 15-fold when VirAG was overproduced. Surprisingly, actin polymerization was found to be dispensable for virulence in hamsters. In contrast, genes encoding a T6S system were up-expressed as much as 30-fold and mutations in this T6S gene cluster resulted in strains that were avirulent in hamsters. SDS-PAGE and mass spectrometry demonstrated that BMAA0742 was secreted by the T6S system when virAG was overexpressed. Purified His-tagged BMAA0742 was recognized by glanders antiserum from a horse, a human and mice, indicating that this Hcp-family protein is produced in vivo during infection.
UR - http://www.scopus.com/inward/record.url?scp=34249980077&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2958.2007.05734.x
DO - 10.1111/j.1365-2958.2007.05734.x
M3 - Article
C2 - 17555434
AN - SCOPUS:34249980077
SN - 0950-382X
VL - 64
SP - 1466
EP - 1485
JO - Molecular Microbiology
JF - Molecular Microbiology
IS - 6
ER -