Affiliation:
1. Department of Cancer Cell Biology, Harvard School of Public Health, Boston, Massachusetts 02115
Abstract
ABSTRACT
Escherichia coli
responds to oxidative stress by activating sets of coregulated genes that help the cell to maintain homeostasis. Identified previously by genetic and biochemical approaches, the
soxRS
system mediates the induction of 18 of these redox-inducible genes (including the
soxS
gene itself). An overlapping set of genes is activated by an assortment of structurally unrelated molecules with antibiotic activities; many genes in this response are controlled by the
marRAB
system. The activation of either the
soxRS
or the
marRAB
system results in enhanced resistance to both superoxide-generating agents and multiple antibiotics. In order to probe the extent of these regulatory networks, we have measured whole-genome transcriptional profiles of the
E. coli
response to the superoxide-generating agent paraquat (PQ), an inducer of the
soxRS
system, and to the weak acid salt sodium salicylate (NaSal), an inducer of the
marRA
system. A total of 112 genes was modulated in response to PQ, while 134 genes were modulated in response to NaSal. We have also obtained transcriptional profiles of the SoxS and MarA regulons in the absence of global stress, in order to establish the regulatory hierarchies within the global responses. Several previously unrelated genes were shown to be under SoxS or MarA control. The genetic responses to both environmental insults revealed several common themes, including the activation of genes coding for functions that replenish reducing potential; regulate iron transport and storage; and participate in sugar and amino acid transport, detoxification, protein modification, osmotic protection, and peptidoglycan synthesis. A large number of PQ- and NaSal-responsive genes have no known function, suggesting that many adaptive metabolic changes that ensue after stress remain uncharacterized.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
424 articles.
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