油茶转运蛋白基因ABCB26的克隆及表达分析

Cloning and expression analysis of Camellia oleifera transporter gene ABCB26

以油茶(Camellia oleifera)‘华硕’品种为研究对象,通过RT-PCR克隆得到腺苷三磷酸结合盒转运蛋白ABCB基因家族的一个成员,命名为CoABCB26。该基因的开放阅读框(ORF)为1491 bp,共编码496个氨基酸。序列比对发现,油茶CoABCB26基因与茶树(Camellia sinensis)的CsABCB26基因亲缘关系最近,相似性达99%,且具有ABC转运蛋白3个特殊结构域:Walker A结构域、ABC标签序列和Walker B结构域。CoABCB26转运蛋白为稳定的疏水性蛋白,相对分子质量为55.88 kDa,理论等电点为8.69,具有2个跨膜结构域,但不具有信号肽;其二级结构主要由α螺旋和无规卷曲两种元件构成。实时定量PCR结果表明,CoABCB26基因在芽和花粉中的表达量较高,且在授粉78 h时,‘华硕’ב华金’异交组合的花柱中表达量最高,表明CoABCB26基因在油茶后期自交不亲和过程中发挥了重要作用。亚细胞定位发现油茶CoABCB26蛋白主要分布在细胞膜上,可能参与物质的跨膜运输。

A member of ATP binding cassette transporter named CoABCB26 which belonged to ABCB gene family was cloned by RT-PCR from Camellia oleifera cultivar‘Huashuo’.The ORF of the gene was 1491 bp and encoded 496 amino acids.Sequence alignment revealed that CoABCB26 gene of Camellia oleifera had the nerest genetic relationship with CsABCB26 gene of Camellia sinensis and shared 99%homology with it.There were three characteristic domains of ABC transporter:Walker A domain,ABC signature sequence and Walker B domain.CoABCB26 transporter was a stable hydrophobic protein and the protein molecular mass was 55.88 kDa,with theoretical isoelectric point of 8.69,which had two transmembrane structures but no signal peptide.Its secondary structure was mainly composed of two components:alpha helix and Random coil.Real-time quantitative RT-PCR results showed that CoABCB26 gene was highly expressed in buds and pollens.At 78 h of pollination,‘Huashuo’and‘Huajin’outcrosses was specifically highly expressed in style,and suggested that CoABCB26 gene might play an important role in late self-incompatibility of Camellia oleifera.Subcellular localization revealed that the CoABCB26 protein was mainly distributed on the cell membrane and might be involved in the transmembrane transport of substances.