title: Protein S-sulfenylation is a fleeting molecular switch that regulates non-enzymatic oxidative folding.
abstract: The post-translational modification S-sulfenylation functions as a key sensor of oxidative stress. Yet the dynamics of sulfenic acid in proteins remains largely elusive due to its fleeting nature. Here we use single-molecule force-clamp spectroscopy and mass spectrometry to directly capture the reactivity of an individual sulfenic acid embedded within the core of a single Ig domain of the titin protein. Our results demonstrate that sulfenic acid is a crucial short-lived intermediate that dictates the protein's fate in a conformation-dependent manner. When exposed to the solution, sulfenic acid rapidly undergoes further chemical modification, leading to irreversible protein misfolding; when cryptic in the protein's microenvironment, it readily condenses with a neighbouring thiol to create a protective disulfide bond, which assists the functional folding of the protein. This mechanism for non-enzymatic oxidative folding provides a plausible explanation for redox-modulated stiffness of proteins that are physiologically exposed to mechanical forces, such as cardiac titin.
authors.affiliation: Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London WC2R 2LS, UK.
authors.forename: Amy E M
authors.initials: AE
authors.lastname: Beedle
authors.affiliation: Centre of Excellence for Mass Spectrometry, King's College London, London SE5 8AF, UK.
authors.forename: Steven
authors.initials: S
authors.lastname: Lynham
authors.affiliation: Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London WC2R 2LS, UK.
authors.forename: Sergi
authors.initials: S
authors.lastname: Garcia-Manyes
mesh_terms: D003512:Cyclohexanones / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D007700:Kinetics; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D015203:Reproducibility of Results; D000072760:Single Molecule Imaging; D012997:Solvents; D013434:Sulfenic Acids / Q000737:chemistry*
chemical_list: D003512:Cyclohexanones; D004220:Disulfides; D011506:Proteins; D012997:Solvents; D013434:Sulfenic Acids; C004774:dimedone; D003545:Cysteine