Gain-of-function mutations in beet DODA2 identify key residues for betalain pigment evolution
Gain-of-function mutations in beet DODA2 identify key residues for betalain pigment evolution
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DOI：
10.1111/nph.15159
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发表时间：
2018-07-01
期刊：
影响因子：
9.4
通讯作者：
Lloyd, Alan
中科院分区：
文献类型：
--
作者：
Bean, Alexander;Sunnadeniya, Rasika;Lloyd, Alan
甜菜色素生物合成中的关键酶促步骤涉及1 - 3，4-二羟基苯丙氨酸（1-DOPA）转化为甜菜氨酸。能够这样做的一类酶是3，4-二羟基苯丙氨酸4，5-双加氧酶（多达）。在产生甜菜色素的物种中，维持了该基因的多个旁系同源物。通过在甜菜、拟南芥和酵母中表达，检测了两对多达的功能，并通过病毒诱导的基因沉默进行了基因沉默。定点诱变鉴定了甜菜氨酸产生所必需的氨基酸残基。甜菜和紫茉莉都具有在甜菜色素途径中起作用的DODA 1谱系和至少一个不起作用的其他谱系DODA 2。定点突变导致甜菜色素生物合成由以前的非功能性多达，揭示了甜菜色素途径的进化所需的关键残基。多达旁系同源物，一个分支参与甜菜色素生物合成，但其他人没有，是目前在各种Carbellales物种的分歧功能。最少7个氨基酸残基的变化赋予甜菜色素酶活性的甜菜色素非功能性多达parasites，提供深入了解植物中的甜菜色素色素途径的进化。
The key enzymatic step in betalain biosynthesis involves conversion of l-3,4-dihydroxyphenylalanine (l-DOPA) to betalamic acid. One class of enzymes capable of this is 3,4-dihydroxyphenylalanine 4,5-dioxygenase (DODA). In betalain-producing species, multiple paralogs of this gene are maintained. This study demonstrates which paralogs function in the betalain pathway and determines the residue changes required to evolve a betalain-nonfunctional DODA into a betalain-functional DODA.Functionalities of two pairs of DODAs were tested by expression in beets, Arabidopsis and yeast, and gene silencing was performed by virus-induced gene silencing. Site-directed mutagenesis identified amino acid residues essential for betalamic acid production.Beta vulgaris and Mirabilis jalapa both possess a DODA1 lineage that functions in the betalain pathway and at least one other lineage, DODA2, that does not. Site-directed mutagenesis resulted in betalain biosynthesis by a previously nonfunctional DODA, revealing key residues required for evolution of the betalain pathway.Divergent functionality of DODA paralogs, one clade involved in betalain biosynthesis but others not, is present in various Caryophyllales species. A minimum of seven amino acid residue changes conferred betalain enzymatic activity to a betalain-nonfunctional DODA paralog, providing insight into the evolution of the betalain pigment pathway in plants.