彩叶草Rubisco活化酶基因SsRCA的分子特征及其表达模式

Molecular Characteristics and Expression Patterns of a Novel Rubisco Activase Gene,SsRCA,from Solenostemon scutellarioides(L.) Codd

为研究观赏植物彩叶草的光合特性,根据Rubisco活化酶(RCA)的保守区域简并扩增获得的保守片段,采用RACE方法,克隆了RCA全长cDNA,命名为SsRCA(GenBank登录号FJ787730)。SsRCAcDNA全长1 548bp,包含1个1 311bp的ORF框,编码436个氨基酸的前体蛋白。其5-′UTR区含有1个终止子TAA,3-′UTR区具有2个mRNA非稳定性相关的DST-like元件和推测的加尾信号AATAAA。SsRCA蛋白具有定位于叶绿体的N端转运肽,具有2个保守的ATP-binding结构域、1个sensor 2基序和多个磷酸化位点。多序列比对和系统进化分析表明,SsRCA与其他植物的RCA蛋白具有较高的一致性,属于RCA的β亚基。表达分析表明,SsRCA基因在含有绿色组织的茎、叶和萼片表达。在9 h黑暗和15 h光照的光周期处理中,正午时表达量最高,午夜时表达量最低,具有明显的光诱导表达特性。

Rubisco activase（RCA） is required to maintain and regulate the activity of Rubisco,and has an important role in plant photosynthesis.For studying the photosynthesis of Solenostemon scutellarioides（commonly known as coleus）,we cloned a full-length cDNA of Rubisco activase SsRCA（GenBank Accession No.FJ787730） using Rapid-Amplification of cDNA Ends（RACE） according to the conserved region of RCA.The full length of the SsRCA gene was 1 548 bp and contained a 1 311 bp open reading frame（ORF） encoding a 436 amino acid precursor protein.One stop codon（TAA） was found in 5′-UTR,and two DST-like elements（Downstream element related to mRNA instability） and one possible polyadenylation signal,AATAAA,were found in 3′-UTR,respectively.The SsRCA contained a predicted N-terminal transit peptide to chloroplast,two high conserved ATP-binding domains and multiple phosphorylation sites.Multiple sequence alignment and phylogenetic analysis showed that SsRCA belongs to β isoform of RCA protein and has high identities with other plant RCAs.Expression of SsRCA was only detected in green tissues.In the 9 h dark and 15 h light photoperiods,maximal and minimal SsRCA mRNA expression levels were detected at midday and at midnight,respectively.SsRCA has the obvious characteristics of light-induced expression.