An exocytotic mutant of Paramecium caudatum: membrane fusion without secretory contents release

Klauke, Norbert; Kissmehl, Roland; Plattner, Helmut; Haga, Nobuyuki; Watanabe, Tsuyoshi

An exocytotic mutant of Paramecium caudatum: membrane fusion without secretory contents release

Dateien

Plattner_An_exocytotic_1998.pdfGröße: 834.71 KBDownloads: 293

Datum

1998

Autor:innen

Klauke, Norbert

Kissmehl, Roland

Plattner, Helmut

Haga, Nobuyuki

Watanabe, Tsuyoshi

Open Access-Veröffentlichung

Open Access Green

Sammlungen

Biologie

Publikationstyp

Zeitschriftenartikel

Publikationsstatus

Published

Erschienen in

Cell Calcium. 1998, 23(5), pp. 349-360. ISSN 0143-4160. Available under: doi: 10.1016/S0143-4160(98)90030-6

Zusammenfassung

This is a detailed characterization of a secretory mutant incapable of releasing secretory contents despite normal exocytotic membrane fusion performance. Trichocyst non-discharge strain tnd1 of Paramecium caudatum and its wildtype (wt) both show a transient cortical [Ca2+]i increase and exocytotic membrane fusion in response to the polyamine secretagogue, aminoethyldextran (AED), or to caffeine. tnd1 cells frequently display spontaneous Ca2+ signals parallelled by spontaneous exocytotic membrane fusion. This remains undetected, unless the trichocyst matrix is shown to be freely accessible to the inert, non-membrane permeable fluorochrome, F2FITC, from the outside. In these tnd1 cells, spontaneous and AED- or caffeine-induced membrane fusion, always without contents expulsion by decondensation (i.e. several-fold stretching), is ascertained by electron microscopy. Exocytotic openings, with condensed trichocysts retained, may persist for hours without impairing cells. Trichocyst decondensation normally requires micromolar [Ca2+]e, but an increase to 10 mM has no effect on tnd1 trichocyst expansion in vivo or in vitro (when isolated and exposed to ionophore A23187 + Ca2+). Paracrystalline packing of the major secretory components (trichynins) does occur, despite incomplete proteolytic precursor processing (according to SDS-PAGE). However, 45Ca(2+)-binding by secretory components is considerably reduced--the likely cause of the non-discharge phenotype. Our findings imply significant untriggered membrane fusion in a system normally following the triggered pathway and clear separation of exocytotic membrane fusion from any later Ca(2+)-dependent steps of the secretory cycle.

Fachgebiet (DDC)

570 Biowissenschaften, Biologie

Zitieren

ISO 690

KLAUKE, Norbert, Roland KISSMEHL, Helmut PLATTNER, Nobuyuki HAGA, Tsuyoshi WATANABE, 1998. An exocytotic mutant of Paramecium caudatum: membrane fusion without secretory contents release. In: Cell Calcium. 1998, 23(5), pp. 349-360. ISSN 0143-4160. Available under: doi: 10.1016/S0143-4160(98)90030-6

BibTex

@article{Klauke1998exocy-6830,
  year={1998},
  doi={10.1016/S0143-4160(98)90030-6},
  title={An exocytotic mutant of Paramecium caudatum: membrane fusion without secretory contents release},
  number={5},
  volume={23},
  issn={0143-4160},
  journal={Cell Calcium},
  pages={349--360},
  author={Klauke, Norbert and Kissmehl, Roland and Plattner, Helmut and Haga, Nobuyuki and Watanabe, Tsuyoshi}
}

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Universitätsbibliographie

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