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Published on: November 12, 2012
Membrane permeability and sensitivity to lethal heat are affected by lexA and recA mutations in Escherichia coli K12
1Laboratório de Radiobiologia Molecular, Instituto de Biofisica Carlos Chag Filho, Universidade Federal do Rio de Janeiro, Brasil.
Abstract:
Membrane permeability was evaluated in several SOS-deficient strains. Great heat sensitivity was observed in all the lexA (Ind-) strains, which was associated to an increase in membrane permeability (up to 120% increase above the wild-type control), as assayed by the crystal violet (CV) growth inhibition. After irradiation with a single UV dose (75 J.m-2 delivered to wild-type and 2 J.m-2 to the lexA3 strain), survival was followed by plating cells in both nutrient and membrane permeability-selective (nutrient + CV) media and a great lethality due to CV was observed in a lexA mutant, which appeared to be about 100 times more sensitive to CV compared to its wild-type parent strain. The decreased membrane integrity found in the lexA-deficient strains suggests that LexA protein and/or LexA-repressed genes may interact with the bacterial membrane, which could be the location of SOS events.
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