The pea gene NA encodes ent-kaurenoic acid oxidase
The pea gene NA encodes ent-kaurenoic acid oxidase
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DOI：
10.1104/pp.012963
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发表时间：
2003-01-01
期刊：
影响因子：
7.4
通讯作者：
Reid, JB
中科院分区：
文献类型：
--
作者：
Davidson, SE;Elliott, RC;Reid, JB
豌豆（Pisum sativum）中赤霉素（GA）缺陷的矮化 na 突变体严重降低了节间伸长，减少了根系生长，并减小了小叶尺寸。然而，种子发育正常。分离出编码 CYP88A 亚家族细胞色素 P450 单加氧酶的两个基因 PSKAO1 和 PsKAO2。 PsKAO1 和 PsKAO2 均具有对映贝壳杉烯酸氧化酶 (KAO) 活性，当在酵母（酿酒酵母）中表达时，可催化从对映贝壳杉烯酸到 GA(12) 的 GA 生物合成途径的三个步骤。除了中间体ent-7α-羟基贝壳杉烯酸和GA12醛外，还检测到了豌豆KAO活性的一些其他产物，包括ent-6α、7α-二羟基贝壳杉烯酸和7β-羟基贝壳杉烯内酯。 NA 基因编码 PsKAO1，因为在两个独立的突变等位基因 na-1 和 na-2 中，PsKAO1 具有改变的序列，并且 PSKAO1 中与 na-1 等位基因相关的 5 个碱基缺失与矮化 na 表型共分离。 PSKAO1 在茎、顶芽、叶、豆荚和根等器官中表达，先前已证明这些器官中 GA 水平在植物中降低。 PsKAO2 仅在种子中表达，这可以解释植物种子中正常的种子发育和正常的 GA 生物合成。
The gibberellin (GA)-deficient dwarf na mutant in pea (Pisum sativum) has severely reduced internode elongation, reduced root growth, and decreased leaflet size. However, the seeds develop normally. Two genes, PSKAO1 and PsKAO2, encoding cytochrome P450 monooxygenases of the subfamily CYP88A were isolated. Both PsKAO1 and PsKAO2 had ent-kaurenoic acid oxidase (KAO) activity, catalyzing the three steps of the GA biosynthetic pathway from ent-kaurenoic acid to GA(12) when expressed in yeast (Saccharomyces cerevisiae). In addition to the intermediates ent-7alpha-hydroxykaurenoic acid and GA12 aldehyde, some additional products of the pea KAO activity were detected, including ent-6alpha,7alpha-dihydroxykaurenoic acid and 7beta-hydroxykaurenolide. The NA gene encodes PsKAO1, because in two independent mutant alleles, na-1 and na-2, PsKAO1 had altered sequences and the five-base deletion in PSKAO1 associated with the na-1 allele cosegregated with the dwarf na phenotype. PSKAO1 was expressed in the stem, apical bud, leaf, pod, and root, organs in which GA levels have previously been shown to be reduced in na plants. PsKAO2 was expressed only in seeds and this may explain the normal seed development and normal GA biosynthesis in seeds of na plants.