大青杨纤维素合成酶PuCesA6基因cDNA的克隆及序列分析

以大青杨总RNA为模板，通过反转录PCR获得纤维素合成酶PuCesA6基因的全长cDNA序列。序列分析结果表明：其cDNA序列全长3778bp，开放读码框序列3264bp，共编码1087个氨基酸。PuCesA6基因编码的氨基酸序列具备被子植物纤维素合酶基因的特征：锌指结构域、高变区I（HVR—I）、高变区II（HVR—II）与β-糖苷转移酶有关的保守结构域以及8个跨膜区。通过多氨基酸序列比对发现，与光皮桦B1CesA5相似度最高，为89％；其次是玉米ZmCesA8，相似度为80％，且8类CesA的锌指结构与c末端氨基酸序列高度保守。34种CesA蛋白序列的分子进化分析表明，大青杨PuCesA6蛋白与欧洲颤杨PtrCesA6蛋白亲缘关系最近，相似度达99％；和光皮桦BICe．sA5、大桉EgCesA6蛋白同聚为一类。

Cloning and Sequence Character Analysis of Full-Length cDNA of Cellulose Synthase PuCesA6 from Populus ussuriensis

The total RNA extracted from Populus ussuriensis leaves was used for RT -PCR, then the full-length cDNA sequence of cellulose synthase gene （PuCesA6） was amplified. The sequence analysis showed that the full- length cDNA of PuCesA6 consisted of 3 778 bp, with an ORF of 3 264 bp encoding 1 087 amino acids. The amino acid sequences of the PuCesA6 showed characteristics of cellulose synthase gene of the angiospermous plant species, i. e. , it contained a ring-type zinc-finger domain, followed by a hyper variable region I （HVR-I） and a hyper varia- ble region II （HVR-II）, a conserved domain related to β-glycoside transferase and 8 transmembrane domains. Homology analysis of the deduced amino acid showed 89% identity to BlCesA5 from Betula luminifera and 80% identity to ZmCesA8 from Zea mays. The sequence analyses results also showed that the ring-type zinc-finger domain of 8 types of cellulose synthase gene CesA and the amino acid sequences at C-terminal domain were highly conservative.