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The Histone Tail of CPAR‐1, a CENP‐A Related Protein, is Cleaved by Separase at the Meiosis I Metaphase‐Anaphase Transition in C. elegans
Author(s) -
Monen Joost,
Hattersley Neil,
Desai Arshad
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.640.1
Subject(s) - anaphase , separase , biology , cohesin , metaphase , meiosis , centromere , microbiology and biotechnology , histone , homologous chromosome , chemistry , genetics , chromosome , gene
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. Support or Funding Information J.M. was supported in part by an Institutional Ruth L. Kirschstein National Research Service Award from the National Institute for General Medical Sciences to the UCSD Genetics Training Program (T32 GM008666). J.M. was supported in part by a grant from the Ramapo College Foundation and Faculty Development Fund. This work was supported by an NIH grant (GM074215) to A.D.