Arevalo-Ferro Catalina, Reil Gerold, Görg Angelika, Eberl Leo, Riedel Kathrin
Department of Microbiology, Technical University of Munich, Am Hochanger 4, D-85350 Freising, Germany.
Syst Appl Microbiol. 2005 Mar;28(2):87-114. doi: 10.1016/j.syapm.2004.10.005.
Pseudomonas putida strains are frequently isolated from the rhizosphere of plants and many strains promote plant-growth, exhibit antagonistic activities against plant pathogens and have the capacity to degrade pollutants. Factors that appear to contribute to the rhizosphere fitness are the ability of the organism to form biofilms and the utilization of cell-to-cell-communication systems (quorum sensing, QS) to co-ordinate the expression of certain phenotypes in a cell density dependent manner. Recently, the ppu QS locus of the tomato rhizosphere isolate P. putida Iso F was characterized and an isogenic QS-negative ppuI mutant P. putida F117 was generated. In the present study we investigated the impact of QS and biofilm formation on the protein profile of surface-associated proteins of P. putida IsoF. This was accomplished by comparative proteome analyses of the P. putida wild type IsoF and the QS-deficient mutant F117 grown either in planktonic cultures or in 60 h old mature biofilms. Differentially expressed proteins were identified by peptide mass fingerprinting and database search in the completed P. putida KT2440 genome sequence. The sessile life style affected 129 out of 496 surface proteins, suggesting that a significant fraction of the bacterial genome is involved in biofilm physiology. In surface-attached cells 53 out of 484 protein spots were controlled by the QS system, emphasizing its importance as global regulator of gene expression in P. putida IsoF. Most interestingly, the impact of QS was dependent on whether cells were grown on a surface or in suspension; about 50% of the QS-controlled proteins identified in planktonic cultures were found to be oppositely regulated when the cells were grown as biofilms. Fifty-seven percent of all identified surface-controlled proteins were also regulated by the ppu QS system. In conclusion, our data provide strong evidence that the set of QS-regulated proteins overlaps substantially with the set of proteins differentially expressed in sessile cells.
恶臭假单胞菌菌株经常从植物根际分离得到，许多菌株能促进植物生长，对植物病原体表现出拮抗活性，并且具有降解污染物的能力。似乎有助于根际适应性的因素包括生物体形成生物膜的能力以及利用细胞间通讯系统（群体感应，QS）以细胞密度依赖的方式协调某些表型的表达。最近，对番茄根际分离株恶臭假单胞菌Iso F的ppu QS位点进行了表征，并产生了同基因的QS阴性ppuI突变体恶臭假单胞菌F117。在本研究中，我们研究了群体感应和生物膜形成对恶臭假单胞菌IsoF表面相关蛋白蛋白质谱的影响。这是通过对在浮游培养物或60小时龄成熟生物膜中生长的恶臭假单胞菌野生型IsoF和QS缺陷型突变体F117进行比较蛋白质组分析来完成的。通过肽质量指纹图谱和在完整的恶臭假单胞菌KT2440基因组序列中的数据库搜索来鉴定差异表达的蛋白质。固着生活方式影响了496种表面蛋白中的129种，这表明很大一部分细菌基因组参与了生物膜生理学。在表面附着细胞中，484个蛋白点中的53个受QS系统控制，强调了其作为恶臭假单胞菌IsoF基因表达全局调节因子的重要性。最有趣的是，QS的影响取决于细胞是在表面生长还是在悬浮液中生长；在浮游培养物中鉴定出的约50%受QS控制的蛋白质在细胞作为生物膜生长时被发现受到相反的调节。所有鉴定出的表面控制蛋白中有57%也受ppu QS系统调节。总之，我们的数据提供了强有力的证据，表明QS调节的蛋白质组与固着细胞中差异表达的蛋白质组有很大重叠。
