The rate of water transport through AQPZ and GlpF matches AQP1
Sprache des Vortragstitels:
Biophysical Society 57th Annual Meeting: February 2-6, 2013
Sprache des Tagungstitel:
Andreas Horner, Florian Zocher, Nicole Ollinger, Christine Siligan and Peter Pohl.
Johannes Kepler Universität Linz, Institut für Biophysik, Linz, Austria.
Aquaporins (AQPs) facilitate water transport in all forms of life. Their reported water permeabilities pf span a wide range: from three times the diffusion limit to three orders of magnitude below it. The exact molecular determinants of such diversity are unknown, mainly because the pf values for one and the same protein are so broadly dispersed. For example, four independent molecular dynamics simulations envisioned that water transport through the aquaglyceroprotein GlpF (glycerol facilitator of E.coli) would be much faster than through channels exclusively transporting water, such as the orthodox aquaporins AQPZ (from E.coli) or human AQP1. However, three existing independent experimental studies all conferred the opposite result. To solve the conundrum, we now used (i) fluorescence correlation spectroscopy to count the number of proteins reconstituted per lipid vesicle and (ii) stopped flow measurements to determine pf of these vesicles. We observed an increased water mobility within the water pores of all three proteins AQP1, AQPZ and GlpF.