竹子木质素合成酶基因克隆与分析

Cloning and Bioinformatic Analysis of Lignin Synthase Gene in Bamboo

苯丙氨酸解氨酶(Phenylalanine Ammonia-Lyase,PAL;EC 4.3.1.5)是木质素生物合成过程的关键酶和限速酶,竹材中的木质素含量的降低有利于提高竹浆的品质.采用RACE技术分别从黄古竹(Phyllostachys angusta)等4种竹子中克隆了PAL基因的全长序列,并进行了生物信息学分析.结果显示,PAL基因的开放读码框长度为2 136 bp,共编码712个氨基酸,具有2个外显子和1个内含子;对PAL蛋白单体的三维结构分析显示,PAL蛋白均含有大量的α螺旋和β折叠结构;基于邻接法的进化树对31种植物的PAL基因的氨基酸序列分析表明,竹类植物PAL的氨基酸序列之间同源性较高,与单子叶植物禾本科(除竹亚科植物外)的玉米和甘蔗等的亲缘关系较近,而与双子叶植物的辣椒、烟草、红参、莴笋等亲缘关系较远.

PAL（phenylalanine ammonia-lyase,EC 4.3.1.5） is one of the key enzymes in the process of lignin synthesis.In this paper,the sequence of PAL gene from four varieties of bamboo：Phyllostachys angusta,Pleioblastus maculosoides,Phyllostachys iridescens,Phyllostachys parvifolia were cloned by RACE.The results show that each PAL gene has two exons and one intron,and every ORF（Open Reading Frames） is 2 136 bp length,encoding 712 amino acids.Then the bamboo PAL amino acid sequences and three-dimensional structures were speculated and analyzed.The results indicate that all of the PAL proteins contain a large number of α-helix and β-plated sheet structure.Neighbor-Joining phylogenetic tree based on PAL sequence of bamboos and other 27 plants indicated that PAL gene sequence in bamboo is relatively conservative,and bamboo had very close relationship with that of Zea mays and Saccharum officinarum,and far relationship with that of Capsicum annuum et al.