Plant PIP aquaporin Gating

ALLEVA, KARINA

Louvain-la-neuve

Otro; Seminario LIBST UCLouvain; 2022

Institute of Biomolecular Science and Technology (LIBST)

PIP aquaporin subfamily is a large and highly conserved group of plant aquaporins (AQP). PIP channels present two features that distinguishes them from others AQP: the possibility of forming heterotetramers assembling different paralogues and a pH gating mechanism mediated by the protonation of a histidine residue located in an intracellular loop. I will present recent results from our laboratory focused on elucidating three questions pending clarification about the gating mechanism in these channels: i- what effectively blocks transport in the close state? ii- what is the role of the C-terminal domain in pH sensing? (not solved in crystal structures), iii- which are the structural elements involved in the differences in pH sensing reported for PIP2 homotetramers and PIP2-PIP1 heterotetramers? To answer these questions, we combined experimental and computational approaches (biophysical experiments expressing PIP channels in Xenopus laevis oocytes plus atomistic molecular dynamic simulations on complete models of PIP tetramers). The results presented offer a molecular understanding of the nature of the constriction that defines the close state and mechanistic insight to discuss why the pH at which the open/close transition will occur in channels belonging to this plant AQP subfamily can vary.