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3-羟基-3-甲基戊二酸单酰辅酶A还原酶(3-hydroxy-3-methylglutaryl coenzyme-A reductase,HMGR)是甲羟戊酸途径中的第一个限速酶,在植物细胞萜类物质合成代谢过程中发挥重要作用。但是,HMGR基因在珍稀濒危兰科药用植物铁皮石斛类萜生物合成途径中的作用尚不清楚。本研究利用RT-PCR和RACE技术,首次从铁皮石斛中克隆到一个HMGR基因,命名为DoHMGR1(GenBank注册号JX272632)。DoHMGR1基因cDNA全长2 071 bp,编码一条由562个氨基酸组成的多肽,分子量59.73 kD,等电点6.18。DoHMGR1蛋白包含HMGR蛋白家族的4个保守结构域(63~561、147~551、268~383、124~541)和两个跨膜基序(42~64、85~107)。DoHMGR1基因与多种植物HMGR基因相似性很高(67%~89%),与万代兰、水稻、玉米等单子叶植物亲缘关系较近。DoHMGR1基因具有组织表达特异性,其转录本在石斛根和茎中表达量较高,为叶中的2.13和1.98倍。DoHMGR1基因的分子鉴定为进一步解析该基因在铁皮石斛萜类物质合成代谢途径中的分子调控作用奠定基础。
3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR), the first rate-limiting enzyme in the mevalonate pathway, Terpenoids play an important role in the anabolic process. However, the role of HMGR gene in the terpenoid biosynthesis pathway of the rare and endangered Orchidaceae medicinal plant Dendrobium candidum is not clear. In this study, HMGR gene was cloned from Dendrobium candidum for the first time using RT-PCR and RACE technology and named DoHMGR1 (GenBank accession number JX272632). The DoHMGR1 cDNA is 2 071 bp in length and encodes a polypeptide of 562 amino acids with a molecular mass of 59.73 kD and an isoelectric point of 6.18. The DoHMGR1 protein contains four conserved domains of the HMGR protein family (63-561, 147-551, 268-383, 124-541) and two transmembrane motifs (42-64,85-107). The DoHMGR1 gene has high similarity (67% -89%) with many plant HMGR genes, and is closely related to monocotyledonous plants such as Bandai, rice and maize. The expression of DoHMGR1 gene is tissue-specific, and its transcripts are highly expressed in roots and stems of Dendrobium, which are 2.13 and 1.98 folds of the leaves. The molecular identification of DoHMGR1 gene lays the foundation for further analysis of the molecular regulation of this gene in the metabolic pathway of terpenoids of Dendrobium nobile.