Membrane fusion triggers rapid degradation of two gamete-specific, fusion-essential proteins in a membrane block to polygamy in Chlamydomonas

Yanjie Liu, Michael J. Misamore, William J. Snell

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The plasma membranes of gametes are specialized for fusion, yet, once fusion occurs, in many organisms the new zygote becomes incapable of further membrane fusion reactions. The molecular mechanisms that underlie this loss of fusion capacity (block to polygamy) remain unknown. During fertilization in the green alga Chlamydomonas, the plus gamete-specific membrane protein FUS1 is required for adhesion between the apically localized sites on the plasma membranes of plus and minus gametes that are specialized for fusion, and the minus-specific membrane protein HAP2 is essential for completion of the membrane fusion reaction. HAP2 (GCS1) family members are also required for fertilization in Arabidopsis, and for the membrane fusion reaction in the malaria organism Plasmodium berghei. Here, we tested whether Chlamydomonas gamete fusion triggers alterations in FUS1 and HAP2 and renders the plasma membranes of the cells incapable of subsequent fusion. We find that, even though the fusogenic sites support multi-cell adhesions, triploid zygotes are rare, indicating a fusion-triggered block to the membrane fusion reaction. Consistent with the extinction of fusogenic capacity, both FUS1 and HAP2 are degraded upon fusion. The rapid, fusion-triggered cleavage of HAP2 in zygotes is distinct from degradation occurring during constitutive turnover in gametes. Thus, gamete fusion triggers specific degradation of fusion-essential proteins and renders the zygote incapable of fusion. Our results provide the first molecular explanation for a membrane block to polygamy in any organism.

Original languageEnglish (US)
Pages (from-to)1473-1481
Number of pages9
JournalDevelopment
Volume137
Issue number9
DOIs
StatePublished - May 1 2010

Fingerprint

Chlamydomonas
Membrane Fusion
Marriage
Germ Cells
Zygote
Membranes
Proteins
Cell Membrane
Fertilization
Membrane Proteins
Plasmodium berghei
Triploidy
Chlorophyta
Plasma Cells
Arabidopsis
Cell Adhesion
Malaria

Keywords

  • Chlamydomonas
  • FUS1
  • Gamete fusion
  • HAP2
  • Polygamy

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Medicine(all)

Cite this

Membrane fusion triggers rapid degradation of two gamete-specific, fusion-essential proteins in a membrane block to polygamy in Chlamydomonas. / Liu, Yanjie; Misamore, Michael J.; Snell, William J.

In: Development, Vol. 137, No. 9, 01.05.2010, p. 1473-1481.

Research output: Contribution to journalArticle

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