2026-09-20T13:10:06Zhttps://ecommons.cornell.edu/server/oai/requestoai:ecommons.cornell.edu:1813/21222026-05-13T16:36:35Zcom_1813_35col_1813_47
Kazmierczak, Mark J.
2005-08-03T19:13:43Z
2005-08-03T19:13:43Z
2005-08-03T19:13:43Z
Kazmierczak, M. J., S. C. Mithoe, K. J. Boor, and M. Wiedmann. 2003. Listeria monocytogenes sigmaB regulates stress response and virulence functions. J. Bacteriol. 185:5722-5734.
https://hdl.handle.net/1813/2122
6476023
Dr. Martin Wiedmann, chair;Dr. John Helmann, Dr. Marci Scidmore
The food borne bacterial pathogen Listeria monocytogenes has several
mechanisms for regulating expression of stress response and virulence genes. The
alternative sigma factor sigmaB is a global regulator of genes active under environmental
stress conditions and during stationary phase growth. I identified a large portion of the
genes regulated by sigmaB using a promoter consensus sequence search and microarrays.
sigmaB directly controls expression of at least 54 genes. The genes regulated by sigmaB encode
proteins with a wide variety of functions, including basic metabolic pathways,
membrane solute transporters, and stress resistance. In addition, I found six virulence
genes, including bsh and five internalin genes, to be controlled by sigmaB.
Another protein that regulates virulence gene expression in L. monocytogenes
is PrfA. I measured expression of PrfA-dependent and sigmaB-dependent genes under
conditions that activate each regulator, using quantitative reverse transcription-PCR
(qRT-PCR). I found that sigmaB is active preferentially under environmental stress
conditions, and activity decreases upon internalization of the bacteria by human
epithelial cells. Conversely, PrfA is not active under stress conditions, but is highly
active intracellularly. Additionally, I used qRT-PCR to determine that sigmaB contributes
directly to prfA expression at the P2 promoter region.
One gene initially identified in the microarray analysis to be sigmaB-dependent is
lmo1433, which is predicted to encode glutathione reductase, an enzyme used by some bacteria to counteract oxidative stress. Characterizations of a strain bearing an in
frame polar deletion of lmo1433 (delta-lmo1433), as well as a delta-sigB delta-lmo1433 strain,
showed no difference in the strains' abilities to survive oxidative stress when
compared to their respective parent strains, although presence of an intact sigB allele
was important for survival. Likewise, the delta-lmo1433 and delta-sigB delta-lmo1433 strains did
not show a difference in total glutathione reductase activity or intracellular survival
and spread, as determined by plaquing ability on mouse L2 cell monolayers, when
compared to parent strains.
National Intstitutes of Health, U.S. Department of Agriculture
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American Society for Microbiology Press
bibid: 6476023
Listeria
Sigma B
PrfA
alternative sigma factor
CONTRIBUTIONS OF SIGMA-B AND PRFA TO STRESS RESPONSE AND VIRULENCE GENE EXPRESSION IN LISTERIA MONOCYTOGENES
dissertation or thesis
application/pdf
Publication
Cornell Theses and Dissertations
Kazmierczak, Mark J.
5893a6ea-7af3-41d7-abc6-04bcd26ab5df
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open.access
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<Abstract>The food borne bacterial pathogen Listeria monocytogenes has several
mechanisms for regulating expression of stress response and virulence genes. The
alternative sigma factor sigmaB is a global regulator of genes active under environmental
stress conditions and during stationary phase growth. I identified a large portion of the
genes regulated by sigmaB using a promoter consensus sequence search and microarrays.
sigmaB directly controls expression of at least 54 genes. The genes regulated by sigmaB encode
proteins with a wide variety of functions, including basic metabolic pathways,
membrane solute transporters, and stress resistance. In addition, I found six virulence
genes, including bsh and five internalin genes, to be controlled by sigmaB.
Another protein that regulates virulence gene expression in L. monocytogenes
is PrfA. I measured expression of PrfA-dependent and sigmaB-dependent genes under
conditions that activate each regulator, using quantitative reverse transcription-PCR
(qRT-PCR). I found that sigmaB is active preferentially under environmental stress
conditions, and activity decreases upon internalization of the bacteria by human
epithelial cells. Conversely, PrfA is not active under stress conditions, but is highly
active intracellularly. Additionally, I used qRT-PCR to determine that sigmaB contributes
directly to prfA expression at the P2 promoter region.
One gene initially identified in the microarray analysis to be sigmaB-dependent is
lmo1433, which is predicted to encode glutathione reductase, an enzyme used by some bacteria to counteract oxidative stress. Characterizations of a strain bearing an in
frame polar deletion of lmo1433 (delta-lmo1433), as well as a delta-sigB delta-lmo1433 strain,
showed no difference in the strains' abilities to survive oxidative stress when
compared to their respective parent strains, although presence of an intact sigB allele
was important for survival. Likewise, the delta-lmo1433 and delta-sigB delta-lmo1433 strains did
not show a difference in total glutathione reductase activity or intracellular survival
and spread, as determined by plaquing ability on mouse L2 cell monolayers, when
compared to parent strains.</Abstract>
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