Aquaporins in yeasts and filamentous fungi.
Recently, genome sequences from different fungi have become available. This information reveals that yeasts and filamentous fungi possess up to five aquaporins. Functional analyses have mainly been performed in budding yeast, Saccharomyces cerevisiae, which has two orthodox aquaporins and two aquaglyceroporins. Whereas Aqy1 is a spore-specific water channel, Aqy2 is only expressed in proliferating cells and controlled by osmotic signals. Fungal aquaglyceroporins often have long, poorly conserved terminal extensions and differ in the otherwise highly conserved NPA motifs, being NPX and NXA respectively. Three subgroups can be distinguished. Fps1-like proteins seem to be restricted to yeasts. Fps1, the osmogated glycerol export channel in S. cerevisiae, plays a central role in osmoregulation and determination of intracellular glycerol levels. Sequences important for gating have been identified within its termini. Another type of aquaglyceroporin, resembling S. cerevisiae Yfl054, has a long N-terminal extension and its physiological role is currently unknown. The third group of aquaglyceroporins, only found in filamentous fungi, have extensions of variable size. Taken together, yeasts and filamentous fungi are a fruitful resource to study the function, evolution, role and regulation of aquaporins, and the possibility to compare orthologous sequences from a large number of different organisms facilitates functional and structural studies.
Pettersson
Nina
N
Department of Cell and Molecular Biology, Göteborg University, Box 462, S-40530 Göteborg, Sweden.
Filipsson
Caroline
C
Becit
Evren
E
Brive
Lars
L
Hohmann
Stefan
S
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D005658:Fungi / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D026901:Membrane Transport Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D016415:Sequence Alignment
C115153:AQY1 protein, S cerevisiae; C422454:AQY2 protein, S cerevisiae; D020346:Aquaporins; D026901:Membrane Transport Proteins; D029701:Saccharomyces cerevisiae Proteins