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  • Genotype-by-environment interactions govern fitness changes associated with adaptive mutations in two-component response systems
Title: Genotype-by-environment interactions govern fitness changes associated with adaptive mutations in two-component response systems
Introduction:Two-component response systems (TCRS) are the main mechanism by which prokaryotes acclimate to changing environments. These systems are composed of a membrane bound histidine kinase (HK) that senses external signals and a response regulator (RR) that activates transcription of response genes. Despite their known role in acclimation, little is known about the role TCRS play in environmental adaptation. Several experimental evolution studies have shown the acquisition of mutations in TCRS during adaptation, therefore here we set out to characterize the adaptive mechanism resulting from these mutations and evaluate whether single nucleotide changes in one gene could induce variable genotype-by-environment (GxE) interactions. Methods:To do this, we assessed fitness changes and differential gene expression for four adaptive mutations incusS, the gene that encodes the HK CusS,acquired byEscherichia coliduring silver adaptation. Results:Fitness assays showed that as the environment changed, each mutant displayed a unique fitness profile with greatest fitness in the original selection environment. RNAseq then indicated that, in ± silver nitrate, each mutant induces a primary response that upregulatescusS,its RRcusR, and constitutively expresses the target response genescusCFBA. This then induces a secondary response via differential expression of genes regulated by the CusR through TCRS crosstalk. Finally, each mutant undergoes fitness tuning through unique tertiary responses that result in gene expression patterns specific for the genotype, the environment and optimized for the original selection conditions. Discussion:This three-step response shows that different mutations in a single gene leads to individualized phenotypes governed by unique GxE interactions that not only contribute to transcriptional divergence but also to phenotypic plasticity.  more » « less
Award ID(s):
1900220
PAR ID:
10549342
Author(s) / Creator(s):
; ; ; ;
Editor(s):
Spiers, Andrew
Publisher / Repository:
Frontiers in Genetics
Date Published:
Journal Name:
Frontiers in Genetics
Volume:
15
ISSN:
1664-8021
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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