Comparative genomic, proteomic and exoproteomic analyses of three Pseudomonas spp.part 6b

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.

栖息于农作物根际的细菌可通过对复杂形态磷（P）的增溶与再矿化等途径，对作物生长产生有益影响。然而[1]，当前学界对细菌在磷胁迫下的蛋白质组响应机制的认知仍较为有限。本研究针对3株假单胞菌属菌株开展胞外蛋白质组分析，并同步[2]对磷充足与磷匮乏[3]培养条件下的恶臭假单胞菌BIRD-1（BIRD-1）进行蛋白质组分析。比较胞外蛋白质组学分析结果显示，各假单胞菌菌株在低磷浓度环境下的胞外蛋白质组存在显著异质性。除已被充分表征的PHO调节子（PHO regulon）成员（如碱性磷酸酶）外，本研究还鉴定出若干响应磷匮乏的全新蛋白质，包括推定核酸酶、磷酸三酯酶、推定膦酸转运蛋白与外膜蛋白。此外，在BIRD-1中，通过对主调节因子phoBR进行诱变实验，我们证实了若干新型PHO依赖性蛋白的存在。本研究数据拓展了学界对假单胞菌属PHO调节子的认知范畴，涵盖了常用作生物菌剂（bioinoculants）的菌株，为更高效、全面地利用土壤中复合态磷开辟了潜在路径。