毛竹PePsbS1基因的分子特征及其原核表达

Molecular characteristics and prokaryotic expression of PePsbS1 gene from Phyllostachys edulis

PsbS蛋白在植物非光化学淬灭(NPQ)中发挥着重要作用。采用同源比对方法从毛竹(Phyllostachys edulis)全长cDNA文库中得到1个PsbS同源基因序列(FP091683),命名为PePsbS1。该基因全长1 069 bp,具有多种光应答元件和参与光应答的顺式作用元件。PePsbS1的开放阅读框为807 bp,编码一个268 aa的蛋白。蛋白结构分析表明,该蛋白由转导肽(53 aa)和成熟蛋白(215 aa)组成,成熟蛋白包含1个叶绿素a/b结合蛋白功能域、4个跨膜区;疏水性分析表明该蛋白组成氨基酸以疏水性氨基酸为主,占42.5%;Blastp分析发现该蛋白与玉米的一致性最高,达80.3%。构建含有PePsbS1编码成熟蛋白序列的原核表达载体pET23a-PePsbS1-mature,转化大肠杆菌,经IPTG诱导表达后进行SDS-PAGE电泳分析。结果表明,分离纯化获得目的蛋白的分子量约为28 kD,与预测PePsbS1编码成熟蛋白的大小相符。这将有助于对竹子PsbS蛋白结构与功能的深入研究。

PsbS protein has a key role in non-photochemical quenching （NPQ） in plants. A PsbS homologous gene was cloned from the full length eDNA library ofPhyllostachys edulis by alignment method, and designed as PePsbS1 （GenBank No. FP091683）. The full length cDNA ofPePsbS1 is 1 069 bp, containing many kinds of light responsive elements and cis-acting regulatory elements involved in light responsiveness. The open reading frame of PePsbS1 is 807 bp encoding a polypeptide with 268 amino acids. The protein structure analysis indicated that PePsbS1 consisted of transit peptide （53 aa） and mature protein （215 aa） including one chlorophyll a/b binding protein domain and four transmembrane domains. Blastp analysis showed that PePsbS1 had high identities with PsbS 1 of Zea mays to 80.3%. Hydropathy analysis of the deduced amino acid sequence revealed that PePsbS 1 was hydrophobic overall as observed from the hydropathy plot with 42.5% of the total amino acid residues having hy- drophobicity. The prokaryotic expression vector containing fragment of PePsbS1 gene encoding mature protein was constructed and expressed in Escherichia coli induced by IPTG. A purified protein with molecular weight about 28 kD was found through SDS-PAGE electrophoresis, which agreed with that of the predicted mature pro- tein encoded by PePsbS1. This work is helpful for further study on the structure and function of PsbS in bamboo.