Metabolic link between auxin production and specialized metabolites in Sorghum bicolor.
Metabolic link between auxin production and specialized metabolites in Sorghum bicolor.
复制标题
高粱生长素产生和特殊代谢物之间的代谢联系。
DOI：
10.1093/jxb/erac421
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发表时间：
2023
影响因子：
6.9
通讯作者：
Kim,Jeongim
中科院分区：
文献类型：
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作者：
Perez,VeronicaC;Dai,Ru;Tomiczek,Breanna;Mendoza,Jorrel;Wolf,EmilySA;Grenning,Alexander;Vermerris,Wilfred;Block,AnnaK;Kim,Jeongim
醛肟是一种氨基酸衍生物，作为许多特殊代谢物的中间体，包括氰苷、硫代葡萄糖苷和生长素。醛肟的形成主要由79家族的细胞色素P450单加氧酶（CYP79s）催化，该酶可具有广泛或狭窄的底物特异性。除SbCYP79A1外，谷类高粱（sorghum bicolor）中的醛肟生物合成酶尚未被鉴定。本研究鉴定了高粱基因组中9个cyp79编码基因。对CYP79的系统发育分析表明，SbCYP79A61与玉米ZmCYP79A61形成了一个亚枝，此前被认为参与醛肟的生物合成。通过对该高粱酶的瞬时表达和在拟南芥中稳定过表达的功能表征表明，SbCYP79A61可以催化苯丙氨酸生成苯乙醛肟（PAOx），但与玉米酶不同，它对色氨酸没有可检测到的活性。此外，稳定同位素饲养实验后的目标代谢物分析表明，PAOx可以作为高粱中苯乙酸（PAA）的前体，并鉴定出苯氰化物是高粱和玉米中PAOx衍生的PAA生物合成的中间体。综上所述，我们的研究结果表明，SbCYP79A61在高粱中产生PAOx，并可能参与其他含氮苯丙氨酸衍生代谢物的生物合成，参与介导生物和非生物胁迫。
Aldoximes are amino acid derivatives that serve as intermediates for numerous specialized metabolites including cyanogenic glycosides, glucosinolates, and auxins. Aldoxime formation is mainly catalyzed by cytochrome P450 monooxygenases of the 79 family (CYP79s) that can have broad or narrow substrate specificity. Except for SbCYP79A1, aldoxime biosynthetic enzymes in the cereal sorghum (Sorghum bicolor) have not been characterized. This study identified nine CYP79-encoding genes in the genome of sorghum. A phylogenetic analysis of CYP79 showed that SbCYP79A61 formed a subclade with maize ZmCYP79A61, previously characterized to be involved in aldoxime biosynthesis. Functional characterization of this sorghum enzyme using transient expression inNicotiana benthamianaand stable overexpression inArabidopsis thalianarevealed that SbCYP79A61 catalyzes the production of phenylacetaldoxime (PAOx) from phenylalanine but, unlike the maize enzyme, displays no detectable activity against tryptophan. Additionally, targeted metabolite analysis after stable isotope feeding assays revealed that PAOx can serve as a precursor of phenylacetic acid (PAA) in sorghum and identified benzyl cyanide as an intermediate of PAOx-derived PAA biosynthesis in both sorghum and maize. Taken together, our results demonstrate that SbCYP79A61 produces PAOx in sorghum and may serve in the biosynthesis of other nitrogen-containing phenylalanine-derived metabolites involved in mediating biotic and abiotic stresses.