Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
Plant Signal Behav. 2010 Sep;5(9):1147-9. doi: 10.4161/psb.5.9.12676. Epub 2010 Sep 1.
Recently we have reported that the αC-helix in the cyclic nucleotide binding domain (CNBD) is required for channel regulation and function of cyclic nucleotide gated ion channels (CNGCs) in Arabidopsis. A mutation at arginine 557 to cysteine (R557C) in the αC-helix of the CNBD caused an alteration in channel regulation. Protein sequence alignments revealed that R557 is located in a region that is important for calmodulin (CaM) binding. It has been hypothesized that CaM negatively regulates plant CNGCs similar to their counter parts in animals. However, only a handful of studies has been published so far and we still do not have much information about the regulation of CNGCs by CaM. Here, we conducted in silico binding prediction of CaM and Arabidopsis CNGC12 (AtCNGC12) to further study the role of R557. Our analysis revealed that R557 forms salt bridges with both D79 and E83 in AtCaM1. Interestingly, a mutation of R557 to C causes the loss of these salt bridges. Our data further suggests that this alteration in CaM binding causes the observed altered channel regulation and that R557 plays an important role in CaM binding.
最近，我们报道了在拟南芥的环核苷酸门控离子通道（CNGC）中，环核苷酸结合域（CNBD）中的αC-螺旋对于通道调节和功能是必需的。在 CNBD 的αC-螺旋中，精氨酸 557 突变为半胱氨酸（R557C）会导致通道调节的改变。蛋白序列比对表明，R557 位于一个对钙调蛋白（CaM）结合很重要的区域。人们假设 CaM 对植物 CNGCs 的负调控类似于其在动物中的对应物。然而，迄今为止，只有少数研究已经发表，我们仍然没有关于 CaM 对 CNGCs 调节的太多信息。在这里，我们进行了 CaM 和拟南芥 CNGC12（AtCNGC12）的计算机结合预测，以进一步研究 R557 的作用。我们的分析表明，R557 与 AtCaM1 中的 D79 和 E83 形成盐桥。有趣的是，R557 突变为 C 会导致这些盐桥的缺失。我们的数据进一步表明，这种 CaM 结合的改变导致了观察到的通道调节的改变，并且 R557 在 CaM 结合中起着重要作用。
