Previous Article | Next Article ![]()
J. Bacteriol., 12 1997, 7595-7599, Vol 179, No. 23
LA Lambert, K Abshire, D Blankenhorn and JL Slonczewski
Proteins induced by benzoic acid in Escherichia coli were observed on
two-dimensional electrophoretic gels (2-D gels). Cultures were grown in
glucose-rich medium in the presence or absence of 20 mM benzoate at an
external pH of 6.5, where the pH gradient (deltapH) is large and benzoate
accumulates, and at an external pH of 8.0, where deltapH is inverted and
little benzoate is taken up. Radiolabeled proteins were separated on 2-D
gels and were identified on the basis of the index of VanBogelen and
Neidhardt. In the absence of benzoic acid, little difference was seen
between pH 6.5 and pH 8.0; this confirms that the mechanisms of protein
homeostasis in this range are constitutive, including the transition
between positive and inverted deltapH. Addition of benzoate at pH 6.5
increased the expression of 33 proteins. Twelve of the benzoate-induced
proteins were induced at pH 8.0 as well, and nine of these matched proteins
induced by the uncoupler dinitrophenol. Eighteen proteins were induced by
benzoate only at pH 6.5, not at pH 8.0, and were not induced by
dinitrophenol. One may be the iron and pH regulator Fur, which regulates
acid tolerance in Salmonella spp. The other 13 proteins had not been
identified previously. The proteins induced by benzoate only at a low pH
may reflect responses to internal acidification or to accumulation of
benzoate.
Copyright © 1997, American Society for Microbiology
Proteins induced in Escherichia coli by benzoic acid
Department of Biology, Kenyon College, Gambier, Ohio 43022, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»