Site-Specific Proteomic Mapping Identifies Selectively Modified Regulatory Cysteine Residues in Functionally Distinct Protein Networks. Issue 7 (23rd July 2015) - Gould, Neal S.
Summary: S -Acylation, S -glutathionylation, S -nitrosylation, and S -sulfenylation are prominent, chemically distinct modifications that regulate protein function, redox sensing, and trafficking. Although the biological significance of these modifications is increasingly appreciated, their integration in the proteome remains unknown. Novel mass spectrometry-based technologies identified 2, 596 predominately unique sites in 1, 319 mouse liver proteins under physiological conditions. Structural analysis localized the modifications in unique, evolutionary conserved protein segments, outside commonly annotated functional regions. Contrary to expectations, propensity for modification did not correlate with biophysical properties that regulate cysteine reactivity. However, the in vivo chemical reactivity is fine-tuned for specificity, demonstrated by the nominal complementation between the four modifications and quantitative proteomics which showed that a reduction in S -nitrosylation is not correlated with increased S -glutathionylation. A comprehensive survey uncovered clustering of modifications within biologically related protein networks. The data provide the first evidence for the occurrence of distinct, endogenous protein networks that undergo redox signaling through specific cysteine modifications. Graphical Abstract: Highlights: Post-translational modification of cysteine is selective and specific in vivo Minimal crosstalk exists between different modifications The propensity for thiol modification is not due solely to chemical reactivity Abstract : Protein cysteine residues can undergo numerous covalent modifications that elicit specific functional or regulatory effects. Gould et al. utilize unique MS techniques and in-depth bioinformatics analysis to identify proteome-wide protein networks that undergo specific cysteine PTMs under normal signaling in vivo.