Adaptive Mutations in RNA Polymerase and the Transcriptional Terminator Rho Have Similar Effects on Escherichia coli Gene Expression
Year: 2017
Type: article
Abstract: Modifications to transcriptional regulators play a major role in adaptation. Here, we compared the effects of multiple beneficial mutations within and between Escherichia coli rpoB, the gene encoding the RNA polymerase β subunit, and rho, which encodes a transcriptional terminator. These two genes have harbored adaptive mutations in numerous E. coli evolution experiments but particularly in our previous large-scale thermal stress experiment, where the two genes characterized alternative adaptive pathways. To compare the effects of beneficial mutations, we engineered four advantageous mutations into each of the two genes and measured their effects on fitness, growth, gene expression and transcriptional termination at 42.2 °C. Among the eight mutations, two rho mutations had no detectable effect on relative fitness, suggesting they were beneficial only in the context of epistatic interactions. The remaining six mutations had an average relative fitness benefit of ∼20%. The rpoB mutations affected the expression of ∼1,700 genes; rho mutations affected the expression of fewer genes but most (83%) were a subset of those altered by rpoB mutants. Across the eight mutants, relative fitness correlated with the degree to which a mutation restored gene expression back to the unstressed, 37.0 °C state. The beneficial mutations in the two genes did not have identical effects on fitness, growth or gene expression, but they caused parallel phenotypic effects on gene expression and genome-wide transcriptional termination.
Source: Molecular Biology and Evolution
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,418
Funders: National Science Foundation, University of California Institute for Mexico and the United States, Consejo Nacional de Ciencia y Tecnología, National Institutes of Health, University of California, Irvine, National Cancer Institute, National Institute of General Medical Sciences, National Institute of Biomedical Imaging and Bioengineering, National Center for Research Resources, Center for Complex Biological Systems, University of California, Irvine
Awards: G1738746289, COBRE Phase III: Transitional Center for Research on Processes in Evolution, G2042572339, High-Throughput DNA Sequencer, G4461738073, G4631142862, G5025827294, High Throughput DNA Sequencer, Center for Modeling Complex Interactions, G5849328965, G5980120469, Experimental Evolutionary Studies of Temperature Adaptation, G7191885690, Mathematical, Computational and Systems Biology, PacBio RS Single Molecule, Real-Time (SMRT) DNA Sequencer, G8565522207, G9000088035, G9000323126, Cancer Center Support Grant
OpenAlex ID: W2951937015