红树植物秋茄中受盐胁迫抑制的cyclophilin基因的鉴定与表达分析

利用代表性差异分析方法获得秋茄中两个编码亲环素(cyclophilin)蛋白的cDNA片段(称为SRGKC2和SRGKC3),该片段大小分别为282 bp和160 bp;序列分析表明:SRGKC2和SRGKC3是同一基因区域的不同长度片段,SRGKC3是SRGKC2片段的一部分。SRGKC2在84个氨基酸范围内与大戟属cyclophilin蛋白的氨基酸序列的一致性达到90%,SRGKC3在47个氨基酸范围内与蚕豆cyclophilin蛋白的一致性达到93%。Northem分析表明:盐分抑制SRGKC2片段的表达。依赖SRGKC2片段的序列资料,利用cDNA快速末端扩增(RACE)技术获取秋茄中cyclophilin基因的全长cDNA片段(命名为KCCYPl)(GenBank登录号:AY150052)。该cDNA全长约为0.9kb,含有一个516个核苷酸的完整开放阅读框,编码172个氨基酸,等电点为8.57,分子量18.2 KDa。42-49位氨基酸残基为推测的ATP/GTP结合位点A基序(P-loop),48-54位氨基酸残基是插入的7个氨基酸残基。文中还对SRGKC2在不同种中的表达状况进行了分析。

IDENTIFICATION AND EXPRESSION ANALYSIS OF THE CYCLOPHILIN GENE IN KANDELIA CANDEL UNDER STRESS OF SALT

Two cDNA fragments, named for SRGKC2 and SRGKC3, encoding cyclophilin in Kandelia candel were isolated by Representational Difference Analysis of cDNA. The two cDNA fragments were 282 bp and 160 bp, respectively. Sequence analysis shows that both of the SRGKC2 and SRGKC3 come from the same gene region, and SRGKC3 is a part of SRGKC2. In addition the SRGKC2 displayed 90% sequence identity over a region of 84 amino acids to the cyclophilin from Euphorbia esula and the SRGKC3 displayed 93 % sequence identity over a region of 47 amino acids to the fava bean . The Northern blotting showed that the expression of SRGKC2 was suppressed under stress of salt. Based on the sequence of SRGKC2, a full-length cDNA (KCCYP1) was isolated by RACE reaction (This sequence data has been submitted to the EMBL databases under accession No. AY150052). The full-length cDNA was about 0.9 kb, which contained an open reading frame (ORF) of 516 bp and coded for 172 amino acid residues with isoelectric point of 8. 57 and molecular weight of 18. 2 kD. The motif A of the ATP/GTP-binding site in KCCYP1 appears at amino acid residues of 41 - 49, and seven-amino-acids-residue was inserted at 48 - 54 amino acid residues. The expression pat- terns of SRGKC2 in various species were also investigated.