A conserved cysteine residue is involved in disulfide bond formation between plant plasma membrane aquaporin monomers
2012; Portland Press; Volume: 445; Issue: 1 Linguagem: Inglês
10.1042/bj20111704
ISSN1470-8728
AutoresGerd Patrick Bienert, Damien Cavez, Arnaud Besserer, Marie C. Berny, Dimitri Gilis, Marianne Rooman, François Chaumont,
Tópico(s)Plant nutrient uptake and metabolism
ResumoAQPs (aquaporins) are conserved in all kingdoms of life and facilitate the rapid diffusion of water and/or other small solutes across cell membranes. Among the different plant AQPs, PIPs (plasma membrane intrinsic proteins), which fall into two phylogenetic groups, PIP1 and PIP2, play key roles in plant water transport processes. PIPs form tetramers in which each monomer acts as a functional channel. The intermolecular interactions that stabilize PIP oligomer complexes and are responsible for the resistance of PIP dimers to denaturating conditions are not well characterized. In the present study, we identified a highly conserved cysteine residue in loop A of PIP1 and PIP2 proteins and demonstrated by mutagenesis that it is involved in the formation of a disulfide bond between two monomers. Although this cysteine seems not to be involved in regulation of trafficking to the plasma membrane, activity, substrate selectivity or oxidative gating of ZmPIP1s (Zm is Zea mays), ZmPIP2s and hetero-oligomers, it increases oligomer stability under denaturating conditions. In addition, when PIP1 and PIP2 are co-expressed, the loop A cysteine of ZmPIP1;2, but not that of ZmPIP2;5, is involved in the mercury sensitivity of the channels.
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