Identification of Salmonella Typhimurium Deubiquitinase SseL Substrates by Immunoaffinity Enrichment and Quantitative Proteomic Analysis

J Proteome Res. 2015 Sep 4;14(9):4029-38. doi: 10.1021/acs.jproteome.5b00574. Epub 2015 Aug 6.


Ubiquitination is a key protein post-translational modification that regulates many important cellular pathways and whose levels are regulated by equilibrium between the activities of ubiquitin ligases and deubiquitinases. Here, we present a method to identify specific deubiquitinase substrates based on treatment of cell lysates with recombinant enzymes, immunoaffinity purification, and global quantitative proteomic analysis. As a model system to identify substrates, we used a virulence-related deubiquitinase, SseL, secreted by Salmonella enterica serovar Typhimurium into host cells. Using this approach, two SseL substrates were identified in the RAW 264.7 murine macrophage-like cell line, S100A6 and heterogeneous nuclear ribonuclear protein K, in addition to the previously reported K63-linked ubiquitin chains. These substrates were further validated by a combination of enzymatic and binding assays. This method can be used for the systematic identification of substrates of deubiquitinases from other organisms and applied to study their functions in physiology and disease.

Keywords: Ubiquitination; deubiquitinase; mass spectrometry; post-translational modification; substrate identification.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Cell Line
  • Immunoassay
  • Mass Spectrometry
  • Mice
  • Protein Interaction Mapping
  • Protein Processing, Post-Translational
  • Proteomics / methods*
  • Salmonella typhimurium / metabolism*
  • Ubiquitin-Specific Proteases / chemistry
  • Ubiquitin-Specific Proteases / metabolism*
  • Ubiquitination


  • Bacterial Proteins
  • Ubiquitin-Specific Proteases