Universität zu Köln

Komsic-Buchmann, Karin, Woestehoff, Luisa and Becker, Burkhard ORCID: 0000-0002-7965-1396 (2014). The Contractile Vacuole as a Key Regulator of Cellular Water Flow in Chlamydomonas reinhardtii. Eukaryot. Cell, 13 (11). S. 1421 - 1431. WASHINGTON: AMER SOC MICROBIOLOGY. ISSN 1535-9786

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Abstract

Most freshwater flagellates use contractile vacuoles (CVs) to expel excess water. We have used Chlamydomonas reinhardtii as a green model system to investigate CV function during adaptation to osmotic changes in culture medium. We show that the contractile vacuole in Chlamydomonas is regulated in two different ways. The size of the contractile vacuoles increases during cell growth, with the contraction interval strongly depending on the osmotic strength of the medium. In contrast, there are only small fluctuations in cytosolic osmolarity and plasma membrane permeability. Modeling of the CV membrane permeability indicates that only a small osmotic gradient is necessary for water flux into the CV, which most likely is facilitated by the aquaporin major intrinsic protein 1 (MIP1). We show that MIP1 is localized to the contractile vacuole, and that the expression rate and protein level of MIP1 exhibit only minor fluctuations under different osmotic conditions. In contrast, SEC6, a protein of the exocyst complex that is required for the water expulsion step, and a dynamin-like protein are upregulated under strong hypotonic conditions. The overexpression of a CreMIP1-GFP construct did not change the physiology of the CV. The functional implications of these results are discussed.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Komsic-Buchmann, Karin UNSPECIFIED UNSPECIFIED UNSPECIFIED Woestehoff, Luisa UNSPECIFIED UNSPECIFIED UNSPECIFIED Becker, Burkhard UNSPECIFIED orcid.org/0000-0002-7965-1396 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-425109
DOI:	10.1128/EC.00163-14
Journal or Publication Title:	Eukaryot. Cell
Volume:	13
Number:	11
Page Range:	S. 1421 - 1431
Date:	2014
Publisher:	AMER SOC MICROBIOLOGY
Place of Publication:	WASHINGTON
ISSN:	1535-9786
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Botanical Institute
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language V-ATPASE; AQUAPORIN; PYROPHOSPHATASE; MEMBRANE; COMPLEX; PROTEIN; PERMEABILITY; DIVERSITY; EVOLUTION; CHANNELS Multiple languages Microbiology; Mycology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/42510