Biofilm formation of Pseudomonas putida IsoF: the role of quorum sensing as assessed by proteomics.

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.

Setting up standards and a reference map for the alkaline proteome of the Gram-positive bacterium Lactococcus lactis.

Despite the fact that almost 39% of the theoretical expressed proteins of Lactococcus lactis have a predicted isoelectric point above 7, these proteins have not been studied in previous proteome analyses. In the present study, we set up a reference map of alkaline lactococcal proteins by using immobilized pH gradients (IPG) spanning pH 6 to 12 and 9 to 12, and protein identification by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Different electrophoresis systems for isoelectric focusing were evaluated to optimize the first dimension.

Proteome analysis of intraclonal diversity of two Pseudomonas aeruginosa TB clone isolates.

Two strains, Pseudomonas aeruginosa TB10839 and TB121838, which belong to the TB clonal lineage, have been isolated from sputa of cystic fibrosis patients. Despite the fact that the strains are closely related, their pathogenic potential differs dramatically: while strain TB10839 is capable of proliferating in polymorphonuclear granulocytes, strain TB121838 is not. Comparative two-dimensional polyacrylamide gel electrophoresis coupled to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF)-mass spectrometry was employed to map the extracellular, intracellular, and surface sub-proteomes of TB10839 and TB121838 and to identify differentially expressed proteins.

Identification of quorum-sensing regulated proteins in the opportunistic pathogen Pseudomonas aeruginosa by proteomics.

The Gram-negative bacterium Pseudomonas aeruginosa is an opportunistic human pathogen which is responsible for severe nosocomial infections in immunocompromised patients and is the major pathogen in cystic fibrosis. The bacterium utilizes two interrelated quorum-sensing (QS) systems, which rely on N-acyl-homoserine lactone (AHL) signal molecules, to control the expression of virulence factors and biofilm development. In this study, we compared the protein patterns of the intracellular, extracellular and surface protein fractions of the PAO1 parent strain with those of an isogenic lasI rhlI double mutant by means of two-dimensional gel electrophoresis (2-DE).

Analysis of the quorum-sensing regulon of the opportunistic pathogen Burkholderia cepacia H111 by proteomics.

Burkholderia cepacia H111, an important pathogen for persons suffering from cystic fibrosis, employs a quorum-sensing (QS) system, cep, to control expression of virulence factors as well as the formation of biofilms. The QS system is thought to ensure that pathogenic traits are only expressed when the bacterial population density is high enough to overwhelm the host before it is able to mount an efficient response. In this study, we compared the protein pattern of the intracellular, extracellular, and surface protein fractions of an AHL-deficient cepI mutant with the one of the parent strain H111 by means of two-dimensional gel electrophoresis (2-DE).

Sample prefractionation with Sephadex isoelectric focusing prior to narrow pH range two-dimensional gels.

Due to their heterogeneity and huge differences in abundance, the detection and identification of all proteins expressed in eukaryotic cells and tissues is a major challenge in proteome analysis. Currently the most promising approaches are sample prefractionation procedures prior to narrow pH range two-dimensional gel electrophoresis (IPG-Dalt) to reduce the complexity of the sample and to enrich for low abundance proteins. We recently developed a simple, cheap and rapid sample prefractionation procedure based on flat-bed isoelectric focusing (IEF) in granulated gels.

High pressure effects step-wise altered protein expression in Lactobacillus sanfranciscensis.

In this study we investigated the cellular response to the application of high hydrostatic pressure. High pressure is increasingly used for food preservation. With high resolution 2-D electrophoresis we compared the protein patterns of atmospherically grown Lactobacillus sanfranciscensis with those pressure treated up to 200 MPa.

Web-based two-dimensional database of Saccharomyces cerevisiae proteins using immobilized pH gradients from pH 6 to pH 12 and matrix-assisted laser desorption/ionization-time of flight mass spectrometry.

An image based two-dimensional (2-D) reference map of very alkaline yeast cell proteins was established by using immobilized pH gradients (IPG) up to pH 12 (IPG 6-12, IPG 9-12 and IPG 10-12) for 2-D electrophoresis and by using matrix-assisted laser desorption/ionization-time of flight mass spectrometry peptide mass fingerprinting for spot identification. Up to now 106 proteins with theoretical isoelectric points up to pH 11.15 and molecular mass between 7.