纤维素合成酶蛋白(cellulose-synthase proteins, CESA)是一类质膜定位蛋白,以蛋白复合体的形式存在于质膜上合成纤维素,在细胞壁建成和植物生长发育过程中起着非常重要的作用。本研究利用CESA蛋白保守域序列PF03552检索普通烟草(Nicotiana tabacum L.)蛋白序列,并通过拟南芥(Arabidopsis thaliana)10个CESA蛋白序列在普通烟草基因组数据库中利用TBLASTN程序进行比对,共获得21条NtCESA基因候选序列,对这些序列进行蛋白序列理化性质分析、系统进化树构建、基因结构分析、保守结构域及跨膜区分析和组织表达模式分析,并对NtCESA9和NtCESA14两个蛋白进行了亚细胞定位实验。结果表明：获得的21条NtCESA蛋白序列的理化性质相似;系统进化分析将21个NtCESA基因和10个AtCESA基因分成5个分支,每一个分支各成员之间的进化相对保守,基因结构类似,不同分支之间的基因结构差异也较小;NtCESA蛋白结构域相对保守,都含有CESA蛋白典型的N端锌指结构、C端跨膜区和DDD-QXXRW保守功能域;组织表达分析结果表明,大部分NtCESA基因在幼苗和成熟期烟草的根、叶、胚芽和愈伤组织中都有表达,同一个分支中的基因表达模式基本一致,并且NtCESA基因参与初/次生细胞壁纤维素的合成与该基因编码蛋白的跨膜区数目存在关联,表明NtCESA基因家族成员功能上的复杂性;亚细胞定位结果证实NtCESA9和NtCESA14为质膜定位蛋白。本研究为烟草CESA基因家族功能的深入研究奠定了基础。

Cellulose-synthase proteins (CESAs) are membrane localized proteins and they form protein complexes to produce cellulose in the plasma membrane. CESA proteins play very important roles in cell wall construction during plant growth and development. In this study, a total of 21 NtCESA gene sequences were identified by using PF03552 conserved protein sequence and 10 AtCESA protein sequences of Arabidopsis thaliana to blast against the common tobacco (Nicotiana tabacum L.) genome database with TBLASTN protocol. We analyzed the physical and chemical properties of protein sequences based on some software or on-line analysis tools. The results showed that there were no significant variances in terms of the physical and chemical properties of the 21 NtCESA proteins. First, phylogenetic tree analysis showed that 21 NtCESA genes and 10 AtCESA genes were clustered into five groups, and the gene structures were similar among the genes that are clustered into the same group. Second, in all of the 21 NtCESA proteins the conserved zinc finger domain was identified in the N-terminus, transmembrane domains were identified in the C-terminus and the DDD-QXXRW conserved domains were also identified. Third, gene expression analysis results indicated that most NtCESA genes were expressed in roots and leaves of seedling or mature tissues of tobacco, seeds and callus tissues. The genes that clustered into the same group share similar expression patterns. Importantly, NtCESA proteins that are involved in secondary cell wall cellulose synthesis have two extra transmembrane domains compared with that involved in primary cell wall cellulose biosynthesis. In addition, subcellular localization results showed that NtCESA9 and NtCESA14 were two plasma membrane anchored proteins. This study will lay a foundation for further functional characterization of these NtCESA genes.