Identification of a cysteine protease responsible for degradation of sperm histones during male pronucleus remodeling in sea urchins

Maria Imschenetzky, Fredy Díaz, Martin Montecino, Felipe Sierra, Marcia Puchi

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

We have identified a 60-kDa cysteine protease that is associated with chromatin in sea urchin zygotes. This enzyme was found to be present as a proenzyme in unfertilized eggs and was activated shortly after fertilization. At a pH of 7.8-8.0, found after fertilization, the enzyme degraded the five sperm-specific histones (SpH), while the native cleavage-stage (CS) histone variants remained unaffected. Based on its requirements for reducing agents, its inhibition by sulfhydryl blocking compounds and its sensitivity to the cysteine-type protease inhibitors (2S,3S)-trans-epoxysuccinyl-L-leucyl- amido-3-methylbutane-ethyl-ester (E-64 d), cystatin and leupeptin, this protease can be defined as a cysteine protease. Consistently, this protease was not affected by the serine-type protease inhibitors phenylmethylsulfonyl fluoride (PMSF) and pepstatin. The substrate selectivity and pH modulation of the protease activity strongly suggest its role in the removal of sperm- specific histones, which determines sperm chromatin remodeling after fertilization. This suggestion was further substantiated by the inhibition of sperm histones degradation in vivo by E-64 d. Based on these three lines of evidence, we postulate that this cysteine protease is responsible for the degradation of sperm-specific histones which occurs during male pronucleus formation.

Original languageEnglish
Pages (from-to)304-315
Number of pages12
JournalJournal of Cellular Biochemistry
Volume67
Issue number3
DOIs
Publication statusPublished - 1 Dec 1997

Keywords

  • Chromatin
  • Cysteine protease
  • Histones
  • Male pronucleus
  • Sea urchins

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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