title: Testing temperature-induced proteomic changes in the plant-associated bacterium Pseudomonas fluorescens SBW25.
abstract: Traits used by bacteria to enhance ecological performance in natural environments are not well understood. Recognizing that the saprophytic plant-colonizing bacterium Pseudomonas fluorescens SBW25 experiences temperatures in its natural environment significantly cooler than the 28°C routinely used in the laboratory, we identified proteins differentially expressed between 28°C and the more environmentally relevant temperature of 14°C. Of 2102 protein isoforms, 32 were temperature responsive and identified by mass spectrometry. Seven of these (OmpR, MucD, GuaD, OsmY and three of unknown function, Tee1, Tee2 and Tee3) were selected for genetic and ecological analyses. In each instance, changes in protein expression with temperature were mirrored by parallel transcriptional changes. The fitness contribution of the genes encoding each of the seven proteins was larger at 14°C than 28°C and included two cases of trade-offs (enhanced fitness at one temperature and reduced fitness at the other -mucD and tee2 deletions). The relationship between the fitness effects of genes in vitro and in vivo was variable, but two temperature-responsive genes -osmY and mucD- contribute substantially to the ability of P. fluorescens to colonize the plant environment.
authors.affiliation: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK. Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester M13 9PT, UK. Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK. New Zealand Institute for Advanced Study and Allan Wilson Centre for Molecular Ecology and Evolution, Massey University, Private Bag 102904, North Shore Mail Centre 0745, Auckland, New Zealand.
authors.forename: C G
authors.initials: CG
authors.lastname: Knight
authors.forename: X X
authors.initials: XX
authors.lastname: Zhang
authors.forename: A
authors.initials: A
authors.lastname: Gunn
authors.forename: T
authors.initials: T
authors.lastname: Brenner
authors.forename: R W
authors.initials: RW
authors.lastname: Jackson
authors.forename: S R
authors.initials: SR
authors.lastname: Giddens
authors.forename: S
authors.initials: S
authors.lastname: Prabhakar
authors.forename: N
authors.initials: N
authors.lastname: Zitzmann
authors.forename: P B
authors.initials: PB
authors.lastname: Rainey