番木瓜丝氨酸/苏氨酸蛋白激酶类抗病基因同源序列的克隆与特征分析

根据丝氨酸/苏氨酸蛋白激酶类抗病基因产物催化结构域Ⅰ和Ⅸ的氨基酸保守序列设计简并引物,PCR扩增番木瓜叶片基因组DNA和cDNA。在NCBI中用BlastX比对发现,5个来自基因组DNA的克隆和4个来自叶片cDNA的克隆可能编码的氨基酸残基序列属于STK蛋白激酶类抗病基因同源序列片段和受体样蛋白激酶基因的同源片段,命名为gPK1-gPK5和cPK1-cPK4,在GenBank注册得到序列号分别为AY693385-AY693389,AY738762-AY738765。除克隆gPK5含有内含子之外,其它都发现了连续阅读框ORF。通过分析除Gpk5之外的8个克隆可能编码氨基酸序列中丝氨酸/苏氨酸蛋白激酶类蛋白激酶的9个催化保守结构域Ⅰ-Ⅸ,并利用ClustalW软件对8个克隆和已报道的抗病蛋白水稻Xa21和西红柿Pto氨基酸残基序列进行分子系统进化树分析发现,8个克隆不仅是受体样蛋白激酶基因的同源片段而且是抗病候选基因片段。

Isolation and characterization of serine/threonine protein kinase-like disease resistance gene analogs from papaya (Carica papaya)

Based on the conserved amino acid sequences of the catalytic domainⅠand Ⅸ of the Serine/Threonine(STK) protein kinase-like disease resistance genes, the degenerated primers were designed and with which PCR was performed using genomic DNA and cDNA of papaya leaf as templates. PCR products were cloned and position clones were sequenced. Blastx analysis revealed that five clones from genomic DNA and four clones from cDNA were STK protein kinase-like disease resistance genes and receptor-like kinase proteins. They were designated as gPK1-gPK5 and cPK1-cPK4 and were deposited in Genbank under accession numbers of AY693385-AY693389 and AY738762-AY738765. Clone gPK5 contained an intron, while the other eight clones had the continuous ORFs. Characteristics of the nine catalytic domains and molecular phylogenic tree analyzing showed that all the eight clones but the clone gPK5 were not only the disease resistance gene analogs but also the probable receptor-like kinase gene analogs.