Regulated secretion of a serine protease that activates an extracellular matrix-degrading metalloprotease during fertilization in Chlamydomonas.

W. J. Snell, W. A. Eskue, M. J. Buchanan

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

During fertilization in the biflagellated alga, Chlamydomonas reinhardtii, gametes of opposite mating types adhere to each other via agglutinin molecules located on their flagellar surfaces, generating a sexual signal that induces several cellular responses including cell wall release. This cell contact-generated signal is mediated by cAMP and release of the wall, which is devoid of cellulose and contains several hydroxyproline-rich glycoproteins, is due to the activation of a metalloprotease, lysin. Although we originally assumed that lysin would be stored intracellularly in a compartment structurally separate from its substrate, recently we showed that lysin is stored in the periplasm as an inactive, higher relative molecular mass precursor, prolysin (Buchanan, M.J., S. H. Imam, W. A. Eskue, and W. J. Snell. 1989. J. Cell Biol. 108:199-207). Here we show that conversion of prolysin to lysin is due to a cellular, nonperiplasmic enzyme that has the properties of a serine protease. Release of this serine protease into the periplasm is induced by incubation of gametes in dibutyryl cAMP. This may be one of the few examples of regulated secretion of a protease in a eucaryotic microorganism and a novel example of regulated secretion in a plant system.

Original languageEnglish (US)
Pages (from-to)1689-1694
Number of pages6
JournalThe Journal of cell biology
Volume109
Issue number4 Pt 1
DOIs
StatePublished - Oct 1989

ASJC Scopus subject areas

  • Cell Biology

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