Comparative genomic, proteomic and exoproteomic analyses of three Pseudomonas spp. Part 3

Bacteria that inhabit the rhizosphere of agricultural crops can have a beneficial effect on crop growth, including through the solubilisation and remineralisation of complex forms of phosphorus (P). However [1], our understanding of the bacterial proteomic response to P stress is limited. Here, exoproteomic analysis of three Pseudomonas species was performed in unison[2] with proteomic analysis of Pseudomonas putida BIRD-1 (BIRD-1) grown [3]under P replete and P deplete conditions. Comparative exoproteomics revealed marked heterogeneity in the exoproteomes of each Pseudomonas species in response to low concentrations of P. In addition to well-characterised members of the PHO regulon such as alkaline phosphatases, several previously undiscovered proteins are responsive to phosphate depletion including putative nucleases, phosphotriesterases, putative phosphonate transporters and outer membrane proteins. Moreover, in BIRD-1, mutagenesis of the master regulator, phoBR, led us to confirm the addition of several novel PHO-dependent proteins. Our data expands knowledge of the Pseudomonas PHO regulon, including species that are frequently used as bioinoculants, opening up the potential for more efficient and complete use of soil complexed P.