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

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.

SUBMITTER: Goymer P

PROVIDER: S-EPMC1526540 | biostudies-literature | 2006 Jun

REPOSITORIES: biostudies-literature

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

Goymer Patrick P Kahn Sophie G SG Malone Jacob G JG Gehrig Stefanie M SM Spiers Andrew J AJ Rainey Paul B PB

Genetics 20060419 2

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 sin ...[more]

PMID: 16624907

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Project description:Purpose: Protozoan predators affect the structure of bacterial communities, but investigations into how predation influences bacterial evolution and antagonistic behaviours are scarce. We performed a 20-day predator-prey evolution experiment on solid media to investigate the adaptive traits that arise in bacterial prey under continuous protozoan predation. Methods: Pseudomonas fluorescens SBW25 and a wild Acanthamoeba sp. isolate as a predator prey pair co-evolved for 20 days yielded both previously described (Wrinkly Spreader; WS) and novel colony morphotype (Wrinkly Fried Egg; WFE) isolates with conferred grazing resistance. These isolates were subjected to RNAseq profiling with and without predation to determine transcriptional changes contributing to grazing resistance. Results: For differential gene expression the WT SBW25 without predation was used as a baseline. For the WS condition, a total of 881 differentially expressed genes (DEGs) were identified, of which 424 were upregulated and 457 were downregulated. In the WFE condition, a total of 908 DEGs were identified, of which 475 were upregulated and 434 were downregulated. Among all DEGs, 335 upregulated and 313 downregulated genes were shared between the WS1 and WFE conditions Conclusions: Our findings suggest that protozoan predation can profoundly influence the course of genetic and phenotypic evolution in a short period of time. Together, the differential expression results suggest expression of features that would be expected to increase biofilm formation in WFE according to previous studies. However, increased expression of these traits may not lead to a stronger biofilm, but may still provide predation resistance. For example, fibrils may increase the effective profile size of a bacterial cell. Increased Fap-mediated biofilm formation also induces increased alginate synthesis in P. aeruginosa PA01, an exopolysaccharide that protects mucoid P. aeruginosa against macrophage killing. Interestingly, we found increased expression of alginate biosynthesis genes in both WFE and WS1 (algA, algF), suggesting alternate mechanisms leading to increased alginate production in these two strains.

Dataset Information

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

Publications

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

Similar Datasets

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