Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2008
Publication Date: 6/2/2008
Citation: Hartney, S.L., Loper, J.E. 2008. Bioinformatic analysis of TonB-dependent receptors of Pseudomonas fluorescens Pf-5. Phytopathology. 98:S66. Interpretive Summary:
Technical Abstract: TonB-dependent receptors (TBDRs) are outer membrane proteins that play essential roles in iron uptake by Gram-negative bacteria. The biological control strain Pseudomonas fluorescens Pf-5 has 45 predicted TBDRs, which far exceeds the number of TBDRs in most published bacterial proteomes. From a phylogenetic analysis of the TBDRs of Pf-5 and other Pseudomonas spp., candidate TBDRs likely to function in iron acquisition have been identified, but there are many that do not appear to function in iron acquisition. Bioinformatic analysis confirmed that all 45 TBDRs of Pf-5 have conserved domains with shared functionality, such as the plug and receptor domains. Eighteen TBDRs were found to have the N-terminal extension domain characteristic of transducers, a subclass of TBDRs that typically initiate a signaling pathway involving anti-sigma factors and extracytoplasmic function (ECF) sigma factors. Sixteen of the putative transducer genes are adjacent to genes encoding an ECF sigma factor and anti-sigma factor in the Pf-5 genome. Five of the 18 putative transducers are related to TBDRs that function in the uptake of ferric-pyoverdines, the fluorescent siderophores produced by Pseudomonas spp., and these are being tested as ferric-pyoverdine receptors in Pf-5. The remaining 27 TBDRs lack the N-terminal extension domain and linked sigma factors, but may function as receptors for a variety of substrates, as found recently in the plant pathogenic bacterium Xanthomonas campestris pv. campestris. TonB-dependent receptors may have important roles influencing the environmental fitness of the biological control strain P. fluorescens Pf-5.