Hetero-oligomerisation of plant plasma membrane aquaporins
(2011) Structure, function, folding and assembly of membrane proteins - Insights from biophysics — Location: Tata (Hongrie) (27.August.2011)
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- Aquaporins are water channels present in biological membranes. They assemble as tetramers but monomers are the functional units. Among plant aquaporins, the Plasma membrane Intrinsic Proteins (or PIPs) cluster in two groups (PIP1 and PIP2) exhibiting different water channel activity when expressed in Xenopus oocytes. Interestingly, PIP1 and PIP2 proteins form heterotetramers resulting in regulation of their localisation and transport activity (Fetter et al., 2004 ; Zelazny et al., 2007; Bellati et al., 2010 ; Otto et al., 2010). We also showed that PIP heterotetramers is composed by two homodimers. However, less is known concerning the interacting motifs between monomers. We focused on maize ZmPIP1;2 and ZmPIP2;5 heterotetramers and generated models of the complex by satisfaction of spatial restraints, using the Modeller program (Eswar et al., 2006). Models were then analysed using the Protein Interaction Calculator tool (Tina et al., 2007) and we identified putative important interacting residues between monomers. Some of them were mutated and the proteins expressed in Xenopus oocytes to carry out swelling experiments. Preliminary experiments allowed us to identify several residues in ZmPIP2;5 and ZmPIP1;2 that had an impact on the water permeability of the cell membrane.
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Berny, M. (2011). Hetero-oligomerisation of plant plasma membrane aquaporins. https://hdl.handle.net/2078.5/208154