chapter  5
24 Pages

Yeast Aquaporins and Aquaglyceroporins: A Matter of Lifestyle

Yeasts and fungi possess dierent numbers of aquaporins and aquaglyceroporins that can be divided into dierent subgroups. Yeast aquaporins not only appear to confer an adaptive advantage to freeze-thaw cycles but also may participate in determining cell surface properties. ose properties are in turn important for substrate adhesion and invasion. e aquaglyceroporin Fps1 appears to be a yeast invention and plays a central role in osmoregulation. Although restricted to a conned group of yeasts, Fps1

CONTENTS Abstract 77 5.1 Introduction 78 5.2Orthodox Aquaporins in Saccharomyces cerevisiae 80

5.2.1Shared Roles of Both AQY1 and AQY2 in Freeze Tolerance 82 5.2.2Aqy1 and Sporulation 84 5.2.3Aqy2 and Colony Morphology 85

5.3Aquaglyceroporins in Saccharomyces cerevisiae 85 5.3.1Role of Fps1: Glycerol Transport and Osmoregulation 86 5.3.2Role of Fps1: Metalloid Transport and Resistance 87 5.3.3Role of Fps1: Acetic Acid Transport and Resistance 88 5.3.4Fps1 Regulation 89 5.3.5Fps1 Sequence 90 5.3.6Y054: e Uncharacterized Protein 92 5.3.7 Y054 Sequence 93

5.4Summary and Future Aspects 93 Acknowledgements 94 References 94

has evolved a rather complex regulation pattern at the crossroad of dierent mitogenactivated protein kinases.