tailieunhanh - Báo cáo khóa học: Identification of residues controlling transport through the yeast aquaglyceroporin Fps1 using a genetic screen
Aquaporins andaquaglyceroporinsmediate the transport of waterand cerevisiaeFps1 is an aquaglyceroporin that mediates controlled glycerol export during osmoregulation. The transport function of Fps1 is rapidly regulated by osmotic changes in an apparently unique way and distinct regions within the longN-andC-terminal extensions are needed for this regulation. Inorder to learnmoreabout themechanisms that control Fps1 we have set up a genetic screen for hyperactive Fps1 and isolated mutations in 14 distinct resi-dues, all facing the inside of the cell. . | Eur. J. Biochem. 271 771-779 2004 FEBS 2004 doi Identification of residues controlling transport through the yeast aquaglyceroporin Fps1 using a genetic screen Sara Karlgren1 Caroline Filipsson2 Jonathan G. L. Mullins3 Roslyn M. Bill1 4 Markus J. Tamas1 and Stefan Hohmann1 1 Department of Cell and Molecular BiologyịMicrobiology Goteborg University Sweden department of Biochemistry and Biophysics Goteborg University Sweden 3Swansea Clinical School University of Wales Swansea UK 4School of Life and Health Sciences Alston Universtty Birmingham UK Aquaporins and aquaglyceroporins mediate the transport of water and solutes across biological membranes. Saccharo-myces Fps1 is an aquaglyceroporin that mediates controlled glycerol export during osmoregulation. The transport function of Fps1 is rapidly regulated by osmotic changes in an apparently unique way and distinct regions within the long N- and C-tenninal xxlensinns are eeeded for this regulation. In order to learn more about the mechanisms that control Fps1 we have set up a genetic screen for hyperactive Fps1 and isolated mutations in 14 distinct residues all facing the inside of the cell. Five of the residues lie within the previously characterized N-terminal regulatory domain and two mutations are located within the approach to the hrst transmembrane domain. Three mutations cause truncation of the C-terminus confirming previous studies on the importance of this region for channel control. Furthermore the novel mutations identify two conserved residues in the channel-forming B-loop as critical for channel control. Structural modelling-based rationalization of the observed mutations supports the notion that the N-terminal regulatory domain and the B-loop could interact in channel control. Our findings provide a framework for further genetic and structural analysis to better understand the mechanism that controls Fps1 function by osmotic changes. Keywords aquaglycrroporin channel .
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