CYP703是一种仅存在于陆地植物中的细胞色素P450家族。通常,每个植物物种都包含一个CYP703。拟南芥CYP703A2在发育中的花药中表达。表达在四分体阶段开始,并仅限于微孢子和珠心细胞层。拟南芥CYP703A2敲除株系显示出受损的花粉发育和部分雄性不育表型。敲除植物花粉的扫描电子显微镜和透射电子显微镜显示出花粉壁的发育受到影响,外壳缺失。花粉粒周围的荧光层归因于孢子壳素中苯丙烷单元的存在,在CYP703A2敲除株系中不存在。在酵母细胞中异源表达CYP703A2表明,CYP703催化将中链饱和脂肪酸转化为相应的单羟基化脂肪酸,优先在C-7位置羟化月桂酸。与发育中的花提取物一起孵育重组CYP703,确认月桂酸和链内羟基月桂酸是植物体内的底物和产物。这些数据表明,链内羟基月桂酸是孢子壳素合成的必要构建块,并使其与苯丙烷单元形成酯和醚键。这项研究确定CYP703是一个特定参与花粉发育的P450家族。
Overexpression of human CYP4Z1, a cytochrome P450 enzyme, has been correlated with poor prognosis in human cancer. However, its catalytic properties are not yet known. We expressed this P450 in
CYP703 is a cytochrome P450 family specific to land plants. Typically, each plant species contains a single CYP703. Arabidopsis thaliana CYP703A2 is expressed in the anthers of developing flowers. Expression is initiated at the tetrad stage and restricted to microspores and to the tapetum cell layer. Arabidopsis CYP703A2 knockout lines showed impaired pollen development and a partial male-sterile phenotype. Scanning electron and transmission electron microscopy of pollen from the knockout plants showed impaired pollen wall development with absence of exine. The fluorescent layer around the pollen grains ascribed to the presence of phenylpropanoid units in sporopollenin was absent in the CYP703A2 knockout lines. Heterologous expression of CYP703A2 in yeast cells demonstrated that CYP703 catalyzes the conversion of medium-chain saturated fatty acids to the corresponding monohydroxylated fatty acids, with a preferential hydroxylation of lauric acid at the C-7 position. Incubation of recombinant CYP703 with methanol extracts from developing flowers confirmed that lauric acid and in-chain hydroxy lauric acids are the in planta substrate and product, respectively. These data demonstrate that in-chain hydroxy lauric acids are essential building blocks in sporopollenin synthesis and enable the formation of ester and ether linkages with phenylpropanoid units. This study identifies CYP703 as a P450 family specifically involved in pollen development.
CYP703是一种仅存在于陆地植物中的细胞色素P450家族。通常,每个植物物种都包含一个CYP703。拟南芥CYP703A2在发育中的花药中表达。表达在四分体阶段开始,并仅限于微孢子和珠心细胞层。拟南芥CYP703A2敲除株系显示出受损的花粉发育和部分雄性不育表型。敲除植物花粉的扫描电子显微镜和透射电子显微镜显示出花粉壁的发育受到影响,外壳缺失。花粉粒周围的荧光层归因于孢子壳素中苯丙烷单元的存在,在CYP703A2敲除株系中不存在。在酵母细胞中异源表达CYP703A2表明,CYP703催化将中链饱和脂肪酸转化为相应的单羟基化脂肪酸,优先在C-7位置羟化月桂酸。与发育中的花提取物一起孵育重组CYP703,确认月桂酸和链内羟基月桂酸是植物体内的底物和产物。这些数据表明,链内羟基月桂酸是孢子壳素合成的必要构建块,并使其与苯丙烷单元形成酯和醚键。这项研究确定CYP703是一个特定参与花粉发育的P450家族。