Laizé V, Tacnet F, Ripoche P, Hohmann S
Department of Cell and Molecular Biology, Microbiology, Göteborg University, Box 462, SE-40530 Göteborg, Sweden.
Yeast. 2000 Jul;16(10):897-903. doi: 10.1002/1097-0061(200007)16:10<897::AID-YEA583>3.0.CO;2-T.
Aquaporin water channels facilitate the transmembrane diffusion of water and higher organisms possess a large number of isoforms. The genome of the yeast Saccharomyces cerevisiae contains two highly similar aquaporin genes, AQY1 and AQY2. AQY1 has been shown to encode a functional water channel but only in certain laboratory strains. Here we show that the AQY2 gene is interrupted by an 11 bp deletion in 23 of the 27 laboratory strains tested, with the exception of strains from the sigma 1278b background, which also exhibit a functional Aqy1p. However, although the AQY2 gene from sigma 1278b is highly homologous to functional aquaporins, we did not observe Aqy2p-mediated water transport in Xenopus oocytes. A survey of 52 yeast strains revealed that all industrial and wild yeasts carry the allele encoding a functional Aqy1p, while none of these strains appear to have a functional Aqy2p. We conclude that natural and industrial conditions provide selective pressure to maintain AQY1 but apparently not AQY2.
水通道蛋白水通道促进水的跨膜扩散，高等生物拥有大量的同工型。酿酒酵母的基因组包含两个高度相似的水通道蛋白基因，AQY1和AQY2。已证明AQY1编码一种功能性水通道，但仅在某些实验室菌株中如此。在这里我们表明，在所测试的27个实验室菌株中的23个中，AQY2基因被一个11 bp的缺失中断，来自sigma 1278b背景的菌株除外，该菌株也表现出功能性的Aqy1p。然而，尽管来自sigma 1278b的AQY2基因与功能性水通道蛋白高度同源，但我们在非洲爪蟾卵母细胞中未观察到Aqy2p介导的水运输。对52个酵母菌株的调查显示，所有工业酵母和野生酵母都携带编码功能性Aqy1p的等位基因，而这些菌株中似乎没有一个具有功能性Aqy2p。我们得出结论，自然和工业条件提供了维持AQY1的选择压力，但显然不是AQY2。
