A conserved cysteine residue is involved in disulfide bond formation between plant plasma membrane aquaporin monomers
A conserved cysteine residue is involved in disulfide bond formation between plant plasma membrane aquaporin monomers
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DOI：
10.1042/bj20111704
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发表时间：
2012-07-01
影响因子：
4.1
通讯作者：
Chaumont, Francois
中科院分区：
文献类型：
--
作者：
Bienert, Gerd P.;Cavez, Damien;Chaumont, Francois
水通道蛋白（AQP）在所有生命界中是保守的，并且促进水和/或其他小溶质穿过细胞膜的快速扩散。在植物水通道蛋白中，PIPs（plasma membrane intrinsic proteins）在植物水分运输过程中起着关键作用，可分为PIP 1和PIP 2两个系统发育组。PIP形成四聚体，其中每个单体充当功能通道。稳定PIP低聚物复合物并负责PIP二聚体对变性条件的抗性的分子间相互作用还没有很好地表征。在本研究中，我们确定了一个高度保守的半胱氨酸残基在环A的PIP 1和PIP 2蛋白，并通过诱变证明，它是参与形成两个单体之间的二硫键。虽然这种半胱氨酸似乎不参与ZmPIP 1（Zm是Zen mays）、ZmPIP 2和杂寡聚体向质膜的运输、活性、底物选择性或氧化门控的调节，但它增加了变性条件下的寡聚体稳定性。此外，当PIP 1和PIP 2共表达时，ZmPIP 1;2的环A半胱氨酸而不是ZmPIP 2;5的环A半胱氨酸参与通道的汞敏感性。
AQPs (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 PIPI 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 Zen 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.