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Christian
D. Mohr, Ph.D.
Assistant Professor
Department of Microbiology
University of Texas Health Science Center, 1993,
Ph.D.,
mohrx005@umn.edu
612-625-7104 office
612-625-6957 lab
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Research Interests:
Research in my laboratory is focused on the virulence factors
and pathogenic mechanisms of the gram-negative bacterium Burkholderia
cepacia. B. cepacia has recently emerged as
an important opportunistic pathogen of the lower respiratory
tract, affecting immunocompromised individuals and particularly
cystic fibrosis (CF) patients.
Projects In My Laboratory:
Type III Secretion
Pathogenesis in a growing number of gram-negative bacteria
is dependent on the secretion of virulence proteins via a
conserved secretory system, termed type III. We have identified
and characterized a genetic locus encoding multiple type III
secretion genes in B. cepacia. Using allelic exchange
mutagenesis, we generated defined null mutations in central
components of the type III secretion system, and demonstrated
that a type III mutant is severely attenuated in virulence
in a murine model of infection. We are currently pursuing
proteomic and genomic-based approaches to identify the secreted
substrates of the B. cepacia type III translocon,
as well as further characterize the role of type III secretion
in modulating the host response to B. cepacia infection.
Cable Pilus Biogenesis
Cable pili are unique peritrichous adherence organelles expressed
by certain strains of B. cepacia. Cable pili have
been shown to mediate binding to both cellular and acellular
receptors, and likely promote B. cepacia colonization
of the respiratory tract of compromised hosts. We have undertaken
a genetic analysis of cable pili and have identified and characterized
a locus (cbl) encoding structural, accessory, and
regulatory components of the cable pilus biosynthetic pathway.
We have also initiated studies to define the regulatory control
of cable pilus gene expression, and have evidence that control
is manifested at both the transcriptional and posttranscriptional
levels. We have recently identified within the cbl
locus three additional genes, designated cblS, cblT
and cblR, predicted to encode new members of the
superfamily of environmentally responsive two-component signal
transduction systems. We are currently utilizing a combined
genetic and biochemical approach to characterize the function
of these genes and to define the signal transduction events
controlling cable pilus gene expression
Electron micrographs
of macrophages infected with Burkholderia cepacia
Electron micrographs
of wild-type Burkholderia cepacia expressing cable
pili (A-D) and a cblA mutant strain (E,F) blocked
in cable pilus expression
Recent Publications:
- Tomich, M. and C. D. Mohr. (2004). Genetic characterization
of a multicomponent signal transduction system controlling
the expression of cable pili in Burkholderia cenocepacia.
J.
Bacteriol. 186:3826-3836.
- Tomich, M. and C. D. Mohr. (2004). Transcriptional and
posttranscriptional control of cable pilus gene expression
in Burkholderia cenocepacia. J.
Bacteriol. 186:1009-1020.
- Tomich, M., A. Griffith, C. A. Herfst, J. L. Burns, and
C. D. Mohr. (2003). Attenuated virulence of a Burkholderia
cepacia type III secretion mutant in a murine model
of infection. Infect.
Immun. 71: 1405-1415.
- Tomich, M., C. A. Herfst, J. W. Golden, and C. D. Mohr.
(2002). Role of flagella in Burkholderia cepacia
host cell invasion. Infect.
Immun. 70:1799-1806.
Last modified on: April 26, 2004
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