Abstract

Aquaporins are members of the major intrinsic protein superfamily of integral membrane proteins that enable the transport of water, glycerol and other solutes across membranes in diverse organisms. In yeasts, the proposed physiological roles of aquaporins are related to their contribution to freeze tolerance, osmoregulation and water transport. This article reports a contribution to the freeze tolerance in the heterologous expression of the Debaryomyces hansenii aquaporin gene in Saccharomyces cerevisiae. In the present experiments, the transformant cells were similarly sensitive to osmotic stress conditions, since their growth capacity phenotype was equivalently abolished in the presence of 0.6 and 1.0 M NaCl. Northern analysis of the yeasts studied revealed a correlation between freeze resistance and the aquaporin gene AQY1.

Key words: Debaryomyces hansenii, Saccharomyces cerevisiae, aquaporin, freeze tolerance.