毛竹PePsbS1基因的分子特征及其原核表达

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。

Molecular characteristics and prokaryotic expression of PePsbS1 gene from Phyllostachys edulis

PsbS protein has a key role in non-photochemical quenching (NPQ) in plants. A PsbS homologous gene was cloned from the full length cDNA library of Phyllostachys edulis by alignment method, and designed as PePsbS1 (GenBank No. FP091683). The full length cDNA of PePsbS1 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 PsbS1 of Zea mays to 80.3%. Hydropathy analysis of the deduced amino acid sequence revealed that PePsbS1 was hydrophobic overall as observed from the hydropathy plot with 42.5% of the total amino acid residues having hydrophobicity. 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 protein encoded by PePsbS1. This work is helpful for further study on the structure and function of PsbS in bamboo.