巨菌草内生固氮菌Klebsiella variicola GN02 nifH基因的克隆及生物信息学分析

Cloning and bioinformatics analysis on nif H gene of endophytic nitrogen-fixing bacteria Klebsiella variicola GN02 isolated from Pennisetum giganteum

研究巨菌草(Pennisetum giganteum)内生固氮菌Klebsiella variicola GN02 nifH基因的生物学信息,对GN02菌株nifH基因进行克隆及完整性验证,并采用多种生物学在线软件对其进行生物信息学预测和分析。结果表明,GN02菌株nifH基因具有完整的ORF,长度882 bp,编码293个氨基酸,NCBI GenBank登录号为MK131264。生物信息学分析表明,GN02菌株nifH基因具有高度保守性,与其他物种来源的nifH基因核苷酸序列及氨基酸序列同源性均达到95%以上。nifH蛋白总相对分子量为31 970.73、理论等电点pI为4.72;跨膜模型倾向N-末端向外的由内到外的跨膜、整个多肽链表现为亲水性;有2个糖基化位点但无分泌信号肽,有可能存在螺旋卷曲结构;二级结构预测表明α-螺旋和无规则卷曲是其多肽链中的主要结构元件,延伸链散布于整个蛋白质中;在数据库中能对该蛋白进行三维同源建模。

To research the bioinformatics on the nifH gene of endophytic nitrogen-fixing bacteria Klebsiella variicola GN02 isolated from Pennisetum giganteum, the nifH gene of GN02 strain was cloned and its integrity was verified, and bioinformatics prediction and analysis of nifH gene were carried out by a variety of online biological software. The results showed that the nifH gene of GN02 strain had a complete ORF, length of 882 bp and encoded 293 amino acid, and the gene accession numbers registered in NCBI GenBank was MK131264. Bioinformatics analysis showed that the nifH gene of GN02 strain was highly conserved and had more than 95% homology with the nucleotide sequence and amino acid sequence of nifH gene from other species. The total relative molecular weight of nifH protein was 31 970.73 and the theoretical isoelectric point pI was 4.72. The transmembrane model inclined to the inward to outward transmembrane of N-end, and the whole polypeptide chain was hydrophilic. nifH protein had two glycosylation sites but no signal peptide secretion, which may had a helical crimp structure. The prediction of secondary structure showed that α-helix and irregular curl were the main structural elements in the polypeptide chain of nifH protein, and the extended chain was scattered in the whole protein. Three-dimensional homologous modeling of nifH protein can be carried out in the database.