Yeast Aquaglyceroporins Use the Transmembrane Core to Restrict Glycerol Transport

Summary, in English

Aquaglyceroporins are transmembrane proteins belonging to the family of aquaporins, which facilitate the passage of specific uncharged solutes across membranes of cells. The yeast aquaglyceroporin Fps1 is important for osmoadaptation by regulating intracellular glycerol levels during changes in external osmolarity. Upon high osmolarity conditions, yeast accumulates glycerol by increased production of the osmolyte and by restricting glycerol efflux through Fps1. The extended cytosolic termini of Fps1 contain short domains that are important for regulating glycerol flux through the channel. Here we show that the transmembrane core of the protein plays an equally important role. The evidence is based on results from an intragenic suppressor mutation screen and domain swapping between the regulated variant of Fps1 from Saccharomyces cerevisiae and the hyperactive Fps1 ortholog from Ashbya gossypii. This suggests a novel mechanism for regulation of glycerol flux in yeast, where the termini alone are not sufficient to restrict Fps1 transport. We propose that glycerol flux through the channel is regulated by interplay between the transmembrane helices and the termini. This mechanism enables yeast cells to fine-tune intracellular glycerol levels at a wide range of extracellular osmolarities.

• Author: Cecilia Geijer; Doryaneh Ahmadpour; Madelene Palmgren; Caroline Filipsson; Dagmara Medrala Klein; Markus J. Tamas; Stefan Hohmann; Karin Lindkvist
• Department/s: Medical Structural Biology
• Publishing year: 2012
• Language: English
• Pages: 23562-23570
• Publication/Series: Journal of Biological Chemistry
• Volume: 287
• Issue: 28
• Links: http://dx.doi.org/10.1074/jbc.M112.353482
• Document type: Journal article
• Publisher: American Society for Biochemistry and Molecular Biology
• Topic: Cell and Molecular Biology
• Status: Published
• Research group: Medical Structural Biology
• ISBN/ISSN/Other: ISSN: 1083-351X