Departamento de Microbiología y Genética, Universidad de Salamanca, Spain.
Fungal Genet Biol. 2010 Sep;47(9):773-81. doi: 10.1016/j.fgb.2010.05.009. Epub 2010 May 23.
Carotene biosynthesis in Phycomyces is photoinducible and carried out by phytoene dehydrogenase (encoded by carB) and a bifunctional enzyme possessing lycopene cyclase and phytoene synthase activities (carRA). A light pulse followed by periods of darkness produced similar biphasic responses in the expression of the carB and carRA genes, indicating their coordinated regulation. Specific binding complexes were formed between the carB-carRA intergenic region and protein extracts from wild type mycelia grown in the dark or 8min after irradiation. These two conditions correspond to the points at which the expression of both genes is minimal, suggesting that these binding complexes are involved in the down-regulation of photocarotenogenesis in Phycomyces. Protein extracts from carotene mutants failed to form the dark retardation complex, suggesting a role of these genes in the regulation of photocarotenogenesis. In contrast, protein extracts from phototropic mutants formed dark retardation complexes identical to that of the wild type.
在根霉中，类胡萝卜素生物合成是光诱导的，由八氢番茄红素脱氢酶（由 carB 编码）和一种具有番茄红素环化酶和八氢番茄红素合酶活性的双功能酶（carRA）完成。光脉冲后再经过黑暗期，会在 carB 和 carRA 基因的表达中产生类似的两相反应，表明它们的协调调节。在黑暗中生长的野生型菌丝体或辐照后 8 分钟的蛋白提取物之间，carB-carRA 基因间区形成了特定的结合复合物。这两种条件都对应于两个基因表达最低的点，这表明这些结合复合物参与了根霉中光类胡萝卜素生物合成的下调。类胡萝卜素突变体的蛋白提取物不能形成黑暗延迟复合物，这表明这些基因在光类胡萝卜素生物合成的调控中起作用。相比之下，向光性突变体的蛋白提取物形成的黑暗延迟复合物与野生型完全相同。
