Regulation of Bacteriodes fragilis katB mRNA by oxidative stress and carbon limitation.
Author
Rocha, Edson R.; Smith, C. Jeffrey
Abstract
Regulation of the katB catalase gene in the anaerobic bacterium Bacteroides fragilis was studied. Northern
blot hybridization analyses revealed that katB was transcribed as an approximately 1.6-kb monocistronic
mRNA. The levels of katB mRNA increased >15-fold when anaerobic, mid-logarithmic-phase cultures were
exposed to O2, O2 with paraquat, or hydrogen peroxide. Under anaerobic conditions, the low levels of katB
mRNA increased in a growth-dependent manner, reaching maximum expression at late logarithmic or early
stationary phase, followed by a decrease in stationary phase. Under anaerobic conditions, the expression of
katB mRNA was strongly repressed by glucose and to a lesser extent by xylose. However, glucose repression was
completely abolished upon exposure to oxygen. The nonfermentable carbon sources fumarate, succinate,
acetate, and pyruvate did not significantly affect expression. Phosphate, nitrogen, and hemin limitation did not
affect the expression of katB mRNA, suggesting that the nutritional control of katB expression is restricted to
carbon and energy sources and not other forms of nutrient limitation. Primer extension analysis revealed that
during both oxidative stress and carbon or energy limitation, katB utilized the same promoter region but
transcription initiation occurred at two different nucleotides separated by 3 or 4 bases. Interestingly, a 6-bp
inverted repeat sequence present in the katB regulatory region was also observed upstream of the B. fragilis
superoxide dismutase gene sod. It is possible that this is a recognition site for a DNA binding protein involved
in the regulation of oxidative stress genes in this organism. Originally published Journal of Bacteriology, Vol. 179, No. 22, Nov. 1997
Subject
Date
1997-11
Citation:
APA:
Rocha, Edson R., & Smith, C. Jeffrey. (November 1997).
Regulation of Bacteriodes fragilis katB mRNA by oxidative stress and carbon limitation..
Journal of Bacteriology,
179(22),
7033-
7039. Retrieved from
http://hdl.handle.net/10342/3077
MLA:
Rocha, Edson R., and Smith, C. Jeffrey.
"Regulation of Bacteriodes fragilis katB mRNA by oxidative stress and carbon limitation.". Journal of Bacteriology.
179:22. (7033-7039),
November 1997.
September 26, 2023.
http://hdl.handle.net/10342/3077.
Chicago:
Rocha, Edson R. and Smith, C. Jeffrey,
"Regulation of Bacteriodes fragilis katB mRNA by oxidative stress and carbon limitation.," Journal of Bacteriology 179, no.
22 (November 1997),
http://hdl.handle.net/10342/3077 (accessed
September 26, 2023).
AMA:
Rocha, Edson R., Smith, C. Jeffrey.
Regulation of Bacteriodes fragilis katB mRNA by oxidative stress and carbon limitation.. Journal of Bacteriology.
November 1997;
179(22):
7033-7039.
http://hdl.handle.net/10342/3077. Accessed
September 26, 2023.
Collections
Publisher
East Carolina University