期刊
BIOLOGICAL CHEMISTRY
卷 394, 期 2, 页码 271-280出版社
WALTER DE GRUYTER & CO
DOI: 10.1515/hsz-2012-0256
关键词
electrophysiology; expression; light-gated ion channel; microbial rhodopsin; optogenetics; protein degradation
资金
- German Research Society, DFG [Sonderforschungsbereich 487]
Channelrhodopsin-2 is a light-gated cation channel from the green alga Chlamydomonas reinhardtii. It is functional in animal cells and therefore widely used for light-activated depolarization, especially in neurons. To achieve a fully functional protein, the chromophore all-trans-retinal is needed. It has not been investigated whether or not the apoprotein is stable without its cofactor until now. Here we show that channelopsin-2 (Chop2, protein without bound retinal) is much more prone to degradation than channelrhodopsin-2 (protein with retinal). Constructs of Chop2 fused to yellow fluorescent protein (Chop2::YFP) in the absence and presence of retinal confirm this observation by exhibiting strongly differing fluorescence. We present mutants of Chop2 with highly increased stability in the absence of retinal. Substitution of threonine 159 with aromatic amino acids causes enhanced resistance to degradation in the absence of retinal, which is confirmed by fluorescence intensity, the increase in photocurrents on the addition of retinal to previously expressed protein, and Western blot analysis. Exchanging threonine 159 with cysteine, however, increases photocurrents due to better binding of retinal, without obvious stabilization against degradation of the retinal-free opsin. We also show that the light-activated hyperpolarizing chloride pump halorhodopsin from Natronomonas pharaonis (NpHR) is not prone to retinal-dependent degradation.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据