Molecular assembly of the period-cryptochrome circadian transcriptional repressor complex

Elife. 2014 Aug 15:3:e03674. doi: 10.7554/eLife.03674.

Abstract

The mammalian circadian clock is driven by a transcriptional-translational feedback loop, which produces robust 24-hr rhythms. Proper oscillation of the clock depends on the complex formation and periodic turnover of the Period and Cryptochrome proteins, which together inhibit their own transcriptional activator complex, CLOCK-BMAL1. We determined the crystal structure of the CRY-binding domain (CBD) of PER2 in complex with CRY2 at 2.8 Å resolution. PER2-CBD adopts a highly extended conformation, embracing CRY2 with a sinuous binding mode. Its N-terminal end tucks into CRY adjacent to a large pocket critical for CLOCK-BMAL1 binding, while its C-terminal half flanks the CRY2 C-terminal helix and sterically hinders the recognition of CRY2 by the FBXL3 ubiquitin ligase. Unexpectedly, a strictly conserved intermolecular zinc finger, whose integrity is important for clock rhythmicity, further stabilizes the complex. Our structure-guided analyses show that these interspersed CRY-interacting regions represent multiple functional modules of PERs at the CRY-binding interface.

Keywords: circadian rhythm; cryptochrome; period.

Publication types

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

MeSH terms

  • ARNTL Transcription Factors / chemistry
  • ARNTL Transcription Factors / genetics
  • ARNTL Transcription Factors / metabolism
  • Amino Acid Sequence
  • Animals
  • Circadian Clocks / genetics*
  • Cryptochromes / chemistry
  • Cryptochromes / genetics*
  • Cryptochromes / metabolism
  • Crystallography, X-Ray
  • F-Box Proteins / chemistry
  • F-Box Proteins / metabolism
  • Gene Expression Regulation*
  • HEK293 Cells
  • Humans
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / genetics*
  • Multiprotein Complexes / metabolism
  • Mutation
  • Period Circadian Proteins / chemistry
  • Period Circadian Proteins / genetics*
  • Period Circadian Proteins / metabolism
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Sequence Homology, Amino Acid
  • Zinc Fingers / genetics

Substances

  • ARNTL Transcription Factors
  • Bmal1 protein, mouse
  • Cry2 protein, mouse
  • Cryptochromes
  • F-Box Proteins
  • Fbxl3 protein, mouse
  • Multiprotein Complexes
  • Per2 protein, mouse
  • Period Circadian Proteins