Abstract
Aquaporin (AQP) water channels facilitate the rapid movement across the plasma membrane throughout animal and plant kingdoms. A plant AQP, NtAQP has also shown to CO2 gas permeability, enhancing photosynthesis and leaf growth, using NtAQP null tobacco. However, to elucidate the physiological role of AQPs, it would be worthwhile to identify AQP inhibitors. Hg2+ is the most popular inhibitor for AQPs so far, and the inhibitory effects of Ag2+ on AQP1 and Ni+ on AQP3 have been recently reported, suggesting AQPs are sensitive to minerals. We, therefore, studied the effects of various minerals on AQP1-AQP5-mediated water and CO2 gas transport in Xenopus oocyte expression system. We found new AQP inhibitors, Zn2+ as an isoform-nonselective inhibitor, and Mn2+ as an AQP4 and AQP5 selective inhibitors. Further, the mineral sensitivity of AQPs-mediated water and CO2 gas transports were different, showing that AQP transport CO2 gas by different mechanism from that for water.
