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Updated: Oct 15, 2026

The Multifaceted Benefits of Protein Co-expression in Escherichia coli
Published on: February 5, 2015
Differential expression of over 60 chromosomal genes in Escherichia coli by constitutive expression of MarA
1Center for Adaptation Genetics and Drug Resistance and the Departments of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Abstract:
In Escherichia coli, the MarA protein controls expression of multiple chromosomal genes affecting resistance to antibiotics and other environmental hazards. For a more-complete characterization of the mar regulon, duplicate macroarrays containing 4,290 open reading frames of the E. coli genome were hybridized to radiolabeled cDNA populations derived from mar-deleted and mar-expressing E. coli. Strains constitutively expressing MarA showed altered expression of more than 60 chromosomal genes: 76% showed increased expression and 24% showed decreased expression. Although some of the genes were already known to be MarA regulated, the majority were newly determined and belonged to a variety of functional groups. Some of the genes identified have been associated with iron transport and metabolism; other genes were previously known to be part of the soxRS regulon. Northern blot analysis of selected genes confirmed the results obtained with the macroarrays. The findings reveal that the mar locus mediates a global stress response involving one of the largest networks of genes described.
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