Ongoing advances in high-throughput technologies have facilitated accurate proteomic measurements and provide a wealth of information on genomic and transcript level. In proteogenomics, this multi-omics data is combined to analyze unannotated organisms and to allow more accurate sample-specific predictions. Existing analysis methods still mainly depend on six-frame translations or reference protein databases that are extended by transcriptomic information or known single nucleotide polymorphisms (SNPs). However, six-frames introduce an artificial sixfold increase of the target database and SNP integration requires a suitable database summarizing results from previous experiments.
The overall workflow of MSProGene. (1) An RNA-Seq read mapping is analyzed to infer transcript sequences, which (2) provide the database for spectra search. (3) The resulting PSMs are represented by a network, which is analyzed to resolve protein inference and to select the correct frame per transcript. (4) Finally, peptide identifications are controlled with regard to their FDR.
Researchers from the Robert Koch Institute overcome these limitations by introducing MSProGene, a new method for integrative proteogenomic analysis based on customized RNA-Seq driven transcript databases. MSProGene is independent from existing reference databases or annotated SNPs and avoids large six-frame translated databases by constructing sample-specific transcripts. In addition, it creates a network combining RNA-Seq and peptide information that is optimized by a maximum-flow algorithm. It thereby also allows resolving the ambiguity of shared peptides for protein inference. The researchers applied MSProGene on three datasets and show that it facilitates a database-independent reliable yet accurate prediction on gene and protein level and additionally identifies novel genes.
Simplified example of a proteogenomic network
Availability – MSProGene is written in Java and Python. It is open source and available at http://sourceforge.net/projects/msprogene/
Contact – firstname.lastname@example.org