Cysteine Oxidation Promotes Dimerization/Oligomerization of Circadian Protein Period 2

Biomolecules. 2022 Jun 25;12(7):892. doi: 10.3390/biom12070892.


The molecular circadian clock is based on a transcriptional/translational feedback loop in which the stability and half-life of circadian proteins is of importance. Cysteine residues of proteins are subject to several redox reactions leading to S-thiolation and disulfide bond formation, altering protein stability and function. In this work, the ability of the circadian protein period 2 (PER2) to undergo oxidation of cysteine thiols was investigated in HEK-293T cells. PER2 includes accessible cysteines susceptible to oxidation by nitroso cysteine (CysNO), altering its stability by decreasing its monomer form and subsequently increasing PER2 homodimers and multimers. These changes were reversed by treatment with 2-mercaptoethanol and partially mimicked by hydrogen peroxide. These results suggest that cysteine oxidation can prompt PER2 homodimer and multimer formation in vitro, likely by S-nitrosation and disulphide bond formation. These kinds of post-translational modifications of PER2 could be part of the redox regulation of the molecular circadian clock.

Keywords: PER2; S-nitrosation; circadian clock; redox.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Circadian Clocks*
  • Circadian Rhythm / physiology
  • Cysteine / metabolism
  • Dimerization
  • Oxidation-Reduction
  • Period Circadian Proteins* / chemistry
  • Period Circadian Proteins* / genetics
  • Period Circadian Proteins* / metabolism
  • Proteins / metabolism


  • Period Circadian Proteins
  • Proteins
  • Cysteine

Grants and funding

This work was supported by Fondo Nacional de Ciencia y Tecnología, Ministerio de Ciencia, Tecnología e Innovación Productiva, Argentina [grant number PICT2014-2099], Universidad Nacional de Quilmes, Argentina [grant number PUNQ 1310/19], Ministerio de Educación, Argentina [BEC-AR program for student mobility].