Separase Cleaves the N-Tail of the CENP-A Related Protein CPAR-1 at the Meiosis I Metaphase-Anaphase Transition in C. elegans

PLoS One. 2015 Apr 28;10(4):e0125382. doi: 10.1371/journal.pone.0125382. eCollection 2015.

Abstract

Centromeres are defined epigenetically in the majority of eukaryotes by the presence of chromatin containing the centromeric histone H3 variant CENP-A. Most species have a single gene encoding a centromeric histone variant whereas C. elegans has two: HCP-3 (also known as CeCENP-A) and CPAR-1. Prior RNAi replacement experiments showed that HCP-3 is the functionally dominant isoform, consistent with CPAR-1 not being detectable in embryos. GFP::CPAR-1 is loaded onto meiotic chromosomes in diakinesis and is enriched on bivalents until meiosis I. Here we show that GFP::CPAR-1 signal loss from chromosomes precisely coincides with homolog segregation during anaphase I. This loss of GFP::CPAR-1 signal reflects proteolytic cleavage between GFP and the histone fold of CPAR-1, as CPAR-1::GFP, in which GFP is fused to the C-terminus of CPAR-1, does not exhibit any loss of GFP signal. A focused candidate screen implicated separase, the protease that initiates anaphase by cleaving the kleisin subunit of cohesin, in this cleavage reaction. Examination of the N-terminal tail sequence of CPAR-1 revealed a putative separase cleavage site and mutation of the signature residues in this site eliminated the cleavage reaction, as visualized by retention of GFP::CPAR-1 signal on separating homologous chromosomes at the metaphase-anaphase transition of meiosis I. Neither cleaved nor uncleavable CPAR-1 were centromere-localized in mitosis and instead localized throughout chromatin, indicating that centromere activity has not been retained in CPAR-1. Although the functions of CPAR-1 and of its separase-dependent cleavage remain to be elucidated, this effort reveals a new substrate of separase and provides an in vivo biosensor to monitor separase activity at the onset of meiosis I anaphase.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Anaphase*
  • Animals
  • Autoantigens / metabolism*
  • Caenorhabditis elegans / cytology*
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins / chemistry*
  • Caenorhabditis elegans Proteins / metabolism
  • Cell Cycle Proteins / chemistry*
  • Cell Cycle Proteins / metabolism
  • Centromere / metabolism
  • Centromere Protein A
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Chromosome Segregation
  • Chromosomes / metabolism
  • Gene Duplication
  • Green Fluorescent Proteins / metabolism
  • Histones / metabolism
  • Meiosis*
  • Metaphase*
  • Molecular Sequence Data
  • Mutation / genetics
  • Oocytes / cytology
  • Oocytes / metabolism
  • Separase / antagonists & inhibitors
  • Separase / metabolism*

Substances

  • Autoantigens
  • CPAR-1 protein, C elegans
  • Caenorhabditis elegans Proteins
  • Cell Cycle Proteins
  • Centromere Protein A
  • Chromosomal Proteins, Non-Histone
  • Histones
  • Green Fluorescent Proteins
  • Separase