高等植物光系统Ⅱ的大量捕光天线(the major light-harvesting complexes of photosystemⅡ,LHCⅡb)是具有高效捕捉光能、传递光能特性的色素蛋白复合物。定点突变是提高膜蛋白稳定性的方法之一。本文应用计算机辅助设计,将定点突变应用于提高LHCIIb稳定性的研究,发现位于跨膜螺旋边缘的突变I124L,明显提高了稳定性。对124位进一步的研究还发现,只有当该位点的氨基酸为具有较大疏水性残基的非极性氨基酸时,才有可能提高稳定性。
The light harvesting chlorophyll a/b-binding protein is one of key proteins in the transformation from light energy to chemical energy. An open reading frame coding precursor protein of cab gene was cloned from the first strand of bamboo cDNA through RT-PCR methods,and named as cab-PhE1 (cab gene 1 from Phyllostachys edulis EF207229). The sequence analysis showed that the deduced polypeptide was highly homologous to some other CAB proteins from monocotyledon,and the gene belonged to lhcb2 family. Tissue specific expression showed that cab-PhE1 expressed higher in leaf than sheath and stem. The prokaryotic expression vector of cab-PhE1 gene encoding the mature protein was constructed by subcloning the fragment into pET-23 a and was expressed in Escherichia coli induced by IPTG. The molecular weight of the induced protein was about 28 ku,approximate to that of the mature protein. This work is a key to the further research on in vitro reconstitution of light-harvesting Chl a/b complexes.
