Targeted proteomics and absolute protein quantification for the construction of a stoichiometric host-pathogen surface density model

Research output: Contribution to journalArticle


Sepsis is a systemic immune response responsible for considerable morbidity and mortality. Molecular modeling of host-pathogen interactions in the disease state represents a promising strategy to define molecular events of importance for the transition from superficial to invasive infectious diseases. Here we used the Gram-positive bacterium Streptococcus pyogenes as a model system to establish a mass spectrometry based workflow for the construction of a stoichiometric surface density model between the S. pyogenes surface, the surface virulence factor M-protein, and adhered human blood plasma proteins. The workflow relies on stable isotope labeled reference peptides and selected reaction monitoring mass spectrometry analysis of a wild-type strain and an M-protein deficient mutant strain, to generate absolutely quantified protein stoichiometry ratios between S. pyogenes and interacting plasma proteins. The stoichiometry ratios in combination with a novel targeted mass spectrometry method to measure cell numbers enabled the construction of a stoichiometric surface density model using protein structures available from the protein data bank. The model outlines the topology and density of the hostpathogen protein interaction network on the S. pyogenes bacterial surface, revealing a dense and highly organized protein interaction network. Removal of the M-protein from S. pyogenes introduces a drastic change in the network topology, validated by electron microscopy. We propose that the stoichiometric surface density model of S. pyogenes in human blood plasma represents a scalable framework that can continuously be refined with the emergence of new results. Future integration of new results will improve the understanding of protein-protein interactions and their importance for bacterial virulence. Furthermore, we anticipate that the general properties of the developed workflow will facilitate the production of stoichiometric surface density models for other types of host-pathogen interactions.


External organisations
  • University of Zurich
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Medical Biotechnology
Original languageEnglish
Pages (from-to)S29-S41
JournalMolecular and Cellular Proteomics
Issue number4
Publication statusPublished - 2017 Apr 1
Publication categoryResearch

Related research output

Sjöholm, K., 2017 May 4, 1 ed. Lund: Department of Immunotechnology, Lund University. 76 p.

Research output: ThesisDoctoral Thesis (compilation)

View all (1)