|Hartney, Sierra -|
Submitted to: International Symposium on Microbiology of Aerial Plant Surfaces
Publication Type: Abstract Only
Publication Acceptance Date: June 18, 2010
Publication Date: August 15, 2010
Citation: Hartney, S., Loper, J.E. 2010. Variation in the TonB-dependent outer-membrane proteins in plant-associated strains of Pseudomonas fluorescens. International Symposium on Microbiology of Aerial Plant Surfaces Program Book. p. 62. Technical Abstract: Nutrient acquisition is key to the ecological fitness of environmental bacteria such as Pseudomonas fluorescens and TonB-dependent outer-membrane proteins are important components of the cellular machinery for the uptake of substrates from the environment. Genomic sequences of ten strains of plant-associated Pseudomonas spp. were surveyed for the presence of TonB-dependent outer-membrane proteins. The strains represent P. fluorescens (seven strains), P. chlororaphis (two strains) and P. synxantha (one strain) isolated from the phyllosphere (two strains) or rhizosphere (eight strains). In addition to published genomic sequences for three strains of P. fluorescens (Pf0-1, Pf-5, and SBW25), draft genomic sequences for seven well-characterized biocontrol strains were also evaluated in this study. The number of TonB-dependent outer-membrane proteins range from 14 in the proteome of P. fluorescens Q2-87 to 45 in P. fluorescens Pf-5. The TonB-dependent outer membrane proteins from all ten genomes were aligned and subjected to maximum parsimony analysis generating two trees (one for transducers and one for receptors, which lack the N-terminal signaling domain) with distinct, well-supported clades. This phylogenetic analysis identified a set of transducers and receptors that are conserved across all genomes. Comparisons to proteins with known functions allowed the assignment of putative roles in heme, ferrichrome, B12, copper, and pyoverdine uptake to conserved TonB-dependent outer-membrane proteins present in all ten strains. The identification of the core and unique sets of TonB-dependent outer-membrane proteins in these genomes will highlight functions conserved across the species as well as those specific to the distinctive lifestyles of each strain.