Biomedical subjects

Pierre-Alain Binz

Publications and source records attributed to Pierre-Alain Binz.

14 recordsLinked to original sources

PubMed2006

Exploring glycopeptide-resistance in Staphylococcus aureus: a combined proteomics and transcriptomics approach for the identification of resistance-related markers.

BACKGROUND: To unravel molecular targets involved in glycopeptide resistance, three isogenic strains of Staphylococcus aureus with different susceptibility levels to vancomycin or teicoplanin were subjected to whole-genome microarray-based transcription and quantitative proteomic profiling. Quantitative proteomics performed on membrane extracts showed exquisite inter-experimental reproducibility permitting the identification and relative quantification of >30% of the predicted S. aureus proteome. RESULTS: In the absence of antibiotic selection pressure, comparison of stable resistant and susceptible strains revealed 94 differentially expressed genes and 178 proteins. As expected, only partial correlation was obtained between transcriptomic and proteomic results during stationary-phase. Application of massively parallel methods identified one third of the complete proteome, a majority of which was only predicted based on genome sequencing, but never identified to date. Several over-expressed genes represent previously reported targets, while series of genes and proteins possibly involved in the glycopeptide resistance mechanism were discovered here, including regulators, global regulator attenuator, hyper-mutability factor or hypothetical proteins. Gene expression of these markers was confirmed in a collection of genetically unrelated strains showing altered susceptibility to glycopeptides. CONCLUSION: Our proteome and transcriptome analyses have been performed during stationary-phase of growth on isogenic strains showing susceptibility or intermediate level of resistance against glycopeptides. Altered susceptibility had emerged spontaneously after infection with a sensitive parental strain, thus not selected in vitro. This combined analysis allows the identification of hundreds of proteins considered, so far as hypothetical protein. In addition, this study provides not only a global picture of transcription and expression adaptations during a complex antibiotic resistance mechanism but also unravels potential drug targets or markers that are constitutively expressed by resistant strains regardless of their genetic background, amenable to be used as diagnostic targets.

Anti-Bacterial Agents↗

PubMed2006

Autumn 2005 Workshop of the Human Proteome Organisation Proteomics Standards Initiative (HUPO-PSI) Geneva, September, 4-6, 2005.

The autumn workshop of the Proteomics Standards Initiative of the Human Proteomics Organisation met to further advance the development of the existing standards in the fields of molecular interactions and mass spectrometry. In addition, new areas were addressed, in particular developing standards for the description and exchange of data from gel electrophoresis experiments. The General Proteomics Standards group is now working closely with the FuGE (Functional Genomics Experiment) efforts to define a general standard in which to encode data that will enable a systems biology approach to data analysis. Common to all these efforts is the field of protein modifications, and work has been initiated to establish an ontology in this field that can be used by both workers in the field of proteomics and the wider scientific community.

Databases, Protein↗

PubMed2006

Automated reprocessing pipeline for searching heterogeneous mass spectrometric data of the HUPO Brain Proteome Project pilot phase.

The newly available techniques for sensitive proteome analysis and the resulting amount of data require a new bioinformatics focus on automatic methods for spectrum reprocessing and peptide/protein validation. Manual validation of results in such studies is not feasible and objective enough for quality relevant interpretation. The necessity for tools enabling an automatic quality control is, therefore, important to produce reliable and comparable data in such big consortia as the Human Proteome Organization Brain Proteome Project. Standards and well-defined processing pipelines are important for these consortia. We show a way for choosing the right database model, through collecting data, processing these with a decoy database and end up with a quality controlled protein list merged from several search engines, including a known false-positive rate.

Algorithms↗

PubMed2005

Further steps towards data standardisation: the Proteomic Standards Initiative HUPO 3(rd) annual congress, Beijing 25-27(th) October, 2004.

The increasing volume of proteomics data currently being generated by increasingly high-throughput methodologies has led to an increasing need for methods by which such data can be accurately described, stored and exchanged between experimental researchers and data repositories. Work by the Proteomics Standards Initiative of the Human Proteome Organisation has laid the foundation for the development of standards by which experimental design can be described and data exchange facilitated. The progress of these efforts, and the direct benefits already accruing from them, were described at a plenary session of the 3(rd) Annual HUPO congress. Parallel sessions allowed the three work groups to present their progress to interested parties and to collect feedback from groups already implementing the available formats.

China↗

PubMed2005

MSight: an image analysis software for liquid chromatography-mass spectrometry.

Images obtained from high-throughput mass spectrometry (MS) contain information that remains hidden when looking at a single spectrum at a time. Image processing of liquid chromatography-MS datasets can be extremely useful for quality control, experimental monitoring and knowledge extraction. The importance of imaging in differential analysis of proteomic experiments has already been established through two-dimensional gels and can now be foreseen with MS images. We present MSight, a new software designed to construct and manipulate MS images, as well as to facilitate their analysis and comparison.

Chromatography, Liquid↗

PubMed2005

5th HUPO BPP Bioinformatics Meeting at the European Bioinformatics Institute in Hinxton, UK--Setting the analysis frame.

The Bioinformatics Committee of the HUPO Brain Proteome Project (HUPO BPP) meets regularly to execute the post-lab analyses of the data produced in the HUPO BPP pilot studies. On July 7, 2005 the members came together for the 5th time at the European Bioinformatics Institute (EBI) in Hinxton, UK, hosted by Rolf Apweiler. As a main result, the parameter set of the semi-automated data re-analysis of MS/MS spectra has been elaborated and the subsequent work steps have been defined.

Computational Biology↗

PubMed2005

Gold coating of non-conductive membranes before matrix-assisted laser desorption/ionization tandem mass spectrometric analysis prevents charging effect.

Acquisition of tandem mass spectra from peptides or other analytes deposited on non-conductive membranes is inhibited on instruments combining matrix-assisted laser desorption/ionization with tandem time-of-flight analyzers (MALDI-TOF/TOF) due to a charging effect. A thin layer of gold renders the membrane conductive. This allows adequate data acquisition on MALDI-TOF/TOF systems. Therefore, this methodology extends the capacity of the molecular scanner concept to tandem mass spectrometry.

Adsorption↗

PubMed2004

The molecular scanner: concept and developments.

Approaches aimed at deciphering the proteome have illustrated the need for relatively complex and highly sensitive methodologies. The major elements of proteome analysis, such as powerful protein separation and enzymatic processing, mass spectrometry and dedicated bioinformatics have been assembled in the development of the molecular scanner. This highly flexible and data-rich approach has combined the power of electrophoretic protein separation, the simultaneous digestion and transfer of proteins through an enzymatic membrane, the immediate use of the MALDI mass spectrometer to scan a collecting membrane, and the development of dedicated bioinformatics tools to perform protein identification and molecular imaging of the proteome. Clinical applications of the molecular scanner have also started to be developed for disease diagnosis in biological material.

Animals↗

PubMed2003

Proteomics application exercise of the Swiss Proteomics Society: report of the SPS'02 session.

After the success of the mass spectrometry (MS) round table that was held at the first Swiss Proteomics Society congress (SPS'01) in Geneva, the SPS has organized a proteomics application exercise and allocated a full session at the SPS'02 congress. The main objective was to encourage the exchange of expertise in protein identification, with a focus on the use of mass spectrometry, and to create a bridge between the users' questions and the instrument providers' solutions. Two samples were sent to fifteen interested labs, including academic groups and MS hardware providers. Participants were asked to identify and partially characterize the samples. They consisted of a complex mixture of peptide/proteins (sample A) and an almost pure recombinant peptide carrying post-translational modifications (sample B). Sample A was an extract of snake venom from the species Bothrops jararaca. Sample B was a recombinant and modified peptide derived from the shrimp Penaeus vannamei penaeidin 3a. The eight labs that returned results reported the use of a wide range of MS instrumentation and techniques. They mentioned a variety of time and manpower allocations. The origin of sample A was generally identified together with a number of database protein entries. The difficulty of the sample identification lay in the incomplete knowledge of the Bothrops species genome sequence and is discussed. Sample B was generally and correctly identified as penaeidin. However, only one group reported the full primary structure. Interestingly, the approaches were again varied and are discussed in the text.

Mass Spectrometry↗

PubMed2003

The Make 2D-DB II package: conversion of federated two-dimensional gel electrophoresis databases into a relational format and interconnection of distributed databases.

The Make 2D-DB tool has been previously developed to help build federated two-dimensional gel electrophoresis (2-DE) databases on one's own web site. The purpose of our work is to extend the strength of the first package and to build a more efficient environment. Such an environment should be able to fulfill the different needs and requirements arising from both the growing use of 2-DE techniques and the increasing amount of distributed experimental data.

Databases, Protein↗

PubMed2003

Mass spectrometry-based proteomics: current status and potential use in clinical chemistry.

For some years now, scientists have been spending a lot of effort in developing methods to analyse and compare complex protein samples. One of the goals of such global analyses of what is known as proteomes is to discover specific protein markers--or fingerprints of protein markers--from various types of affected biological samples. Considering the battery of technologies currently available, mass spectrometry (MS) constitutes an essential tool in proteomics. We describe here the type of MS instrumentation that is currently dedicated to proteomics research. We also describe the major experimental workflows that are typically used in proteomics today, with a focus on those incorporating MS as a major analysis tool.

Chemistry, Clinical↗

PubMed2002

Challenges in mass spectrometry.

Report of the round table discussionThe reported MS round table took place within the ProteomeValley Technology Fair during the Swiss Proteomics Society 2001 Congress. It was organised by the Swiss Proteomics Society (SPS) in collaboration with FontisMedia (http://www.fontismedia. com). It was scheduled November 22(nd), 2001 from 16:40 to 18:00 at the Geneva University Hospital. The objective of the MS round table was to bring together two kinds of specialists in mass spectrometry: those who develop and commercialise MS equipment and those who use it as a tool in proteomic sciences. Six expert users and six representatives of leading MS instrument companies were thus invited to actively participate in this round table and share their points of view. The main objectives of this round table were not only to share experiences, but also to share dreams regarding MS technology and discuss the actual limits. It also focused on what MS users presently expect from MS producers and what are the current priorities in terms of development, for the benefit of all parties. Although it was one of the final events of the meeting, this MS round table attracted an audience of some fifty participants of the congress who were actively involved in the debate.

Ligands↗

PubMed2002

Peptide mass fingerprinting peak intensity prediction: extracting knowledge from spectra.

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry has become a valuable tool in proteomics. With the increasing acquisition rate of mass spectrometers, one of the major issues is the development of accurate, efficient and automatic peptide mass fingerprinting (PMF) identification tools. Current tools are mostly based on counting the number of experimental peptide masses matching with theoretical masses. Almost all of them use additional criteria such as isoelectric point, molecular weight, PTMs, taxonomy or enzymatic cleavage rules to enhance prediction performance. However, these identification tools seldom use peak intensities as parameter as there is currently no model predicting the intensities based on the physicochemical properties of peptides. In this work, we used standard datamining methods such as classification and regression methods to find correlations between peak intensities and the properties of the peptides composing a PMF spectrum. These methods were applied on a dataset comprising a series of PMF experiments involving 157 proteins. We found that the C4.5 method gave the more informative results for the classification task (prediction of the presence or absence of a peptide in a spectra) and M5' for the regression methods (prediction of the normalized intensity of a peptide peak). The C4.5 result correctly classified 88% of the theoretical peaks; whereas the M5' peak intensities had a correlation coefficient of 0.6743 with the experimental peak intensities. These methods enabled us to obtain decision and model trees that can be directly used for prediction and identification of PMF results. The work performed permitted to lay the foundations of a method to analyze factors influencing the peak intensity of PMF spectra. A simple extension of this analysis could lead to improve the accuracy of the results by using a larger dataset. Additional peptide characteristics or even PMF experimental parameters can also be taken into account in the datamining process to analyze their influence on the peak intensity. Furthermore, this datamining approach can certainly be extended to the tandem mass spectrometry domain or other mass spectrometry derived methods.

Acrylamide↗

PubMed2002

Molecular scanner experiment with human plasma: improving protein identification by using intensity distributions of matching peptide masses.

The development of high throughput utilities to identify proteins is a major challenge in present research in the field of proteomics. One such utility, the molecular scanner, uses proteins separated by two-dimensional polyacrylamide gel electrophoresis that are digested in the gel and during transfer onto a collecting membrane. After adding a matrix, the membrane is inserted into a matrix-assisted laser desorption/ionization-time of flight mass spectrometer and a peptide mass fingerprint (PMF) is measured for every scanned site. Since the spacing between scanned sites is much smaller than the size of the most abundant protein spots, there is a certain redundancy in the data that was used in an earlier experiment with Escherichia coli [1] to improve mass calibration and PMF identification results. It was observed that the signal intensity of a peptide mass as a function of the position on the membrane showed similar patterns if peptides stemmed from the same protein. Taking account of these similarities a clustering algorithm was used to find lists of experimental masses with similar intensity distributions, which provided clearer identification of the corresponding proteins. Here, these methods are applied to a human plasma scan, where proteins were highly modified and less separated. The presence of very abundant proteins like albumin and immunoglobulins added another difficulty. The calibration of the initial PMFs was not satisfactory and masses had to be recalibrated. After discarding chemical noise, the membrane was partitioned into regions and for each region protein identification was carried out separately. A new scoring method was used, where the PMF score was multiplied by a factor that measures the similarity of matching peptides. This method proved to be more robust than the method developed in [1] if the region where a protein was found had an extended, nonspherical shape and strong overlap with regions of other proteins. Many proteins annotated on the SWISS-2D PAGE human plasma master gel could be clearly identified and many interesting properties were observed.

Algorithms↗