Adaptive divergence in experimental populations of Pseudomonas fluorescens. II. Role of the GGDEF regulator WspR in evolution and development of the wrinkly spreader phenotype

Patrick Goymer, Sophie G. Kahn, Jacob G. Malone, Stefanie M. Gehrig, Andrew J. Spiers, Paul B. Rainey*

*Corresponding author for this work

Research output: Contribution to journalArticle

72 Citations (Scopus)

Abstract

Wrinkly spreader (WS) genotypes evolve repeatedly in model Pseudomonas populations undergoing adaptive radiation. Previous work identified genes contributing to the evolutionary success of WS. Here we scrutinize the GGDEF response regulator protein WspR and show that it is both necessary and sufficient for WS. Activation of WspR occurs by phosphorylation and different levels of activation generate phenotypic differences among WS genotypes. Five alleles of wspR, each encoding a protein with a single amino acid substitution, were generated by mutagenesis. Two alleles are constitutively active and cause the ancestral genotype to develop a WS phenotype; the phenotypic effects are allele specific and independent of phosphorylation. Three alleles contain changes in the GGDEF domain and when overexpressed in WS cause reversion to the ancestral phenotype. Ability to mimic this effect by overexpression of a liberated N-terminal domain shows that in WS, regulatory components upstream of WspR are overactive. To connect changes at the nucleotide level with fitness, the effects of variant alleles were examined in both structured and unstructured environments: alleles had adaptive and deleterious effects with trade-offs evident across environments. Despite the proclivity of mutations within wspR to generate WS, sequence analysis of wspR from 53 independently obtained WS showed no evidence of sequence change in this gene.

Original languageEnglish
Pages (from-to)515-526
Number of pages12
JournalGenetics
Volume173
Issue number2
DOIs
Publication statusPublished - 1 Jun 2006
Externally publishedYes

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