A negative regulator of light-inducible carotenogenesis in Mucor circinelloides
A negative regulator of light-inducible carotenogenesis in Mucor circinelloides
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DOI：
10.1007/s004380100558
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发表时间：
2001-11-01
影响因子：
3.1
通讯作者：
Ruiz-Vázquez, RM
中科院分区：
文献类型：
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作者：
Navarro, E;Lorca-Pascual, JM;Ruiz-Vázquez, RM
卷枝毛霉通过激活胡萝卜素生物合成来响应蓝光。在黑暗中生长的野生型菌株含有极少量的β-胡萝卜素，因为胡萝卜素生成的结构基因的转录水平较低。当暴露于光脉冲时，这些基因的转录水平强烈增加，导致高浓度的β-胡萝卜素的形成。 crg4基因参与光诱导类胡萝卜素生物合成的调节。该基因最初被鉴定为 3'-截短的 ORF，会在黑暗中导致胡萝卜素过度积累，编码一种富含半胱氨酸、锌结合、环指基序的蛋白质，如在多种调节蛋白中所发现的那样。 crgA 基因的表达由光脉冲激活，其时间过程与胡萝卜素生成的结构基因相似。为了了解 crgA 基因在胡萝卜素生成中的调节作用，我们使用了基于通过基因替换构建 crgA 无效突变体的遗传方法。 crgA 功能的缺乏会导致类胡萝卜素在黑暗和光照下过度积累。将野生型 crgA 等位基因引入这些突变体可恢复胡萝卜素生成的野生型表型。 crgA 无效突变体显示的高水平类胡萝卜素积累与类胡萝卜素结构基因表达的增加相关。这些结果有力地表明，crgA 在 M. circinelloides 中充当光诱导胡萝卜素生成的负调节因子。
Mucor circinelloides responds to blue light by activating carotene biosynthesis. Wild-type strains grown in darkness contain minimal amounts of beta -carotene because of the low levels of transcription of the structural genes for carotenogenesis. When exposed to a light pulse, the level of transcription of these genes increases strongly, leading to the formation of high concentrations of beta -carotene. The crg4 gene is involved in the regulation of light-induced carotenoid biosynthesis. This gene, originally identified as a 3'-truncated ORF which causes carotene over-accumulation in the dark, encodes a protein with a cysteine-rich, zinc-binding, RING-finger motif, as found in diverse groups of regulatory proteins. The expression of the crgA gene is activated by a light pulse, with a time course similar to that of the structural genes for carotenogenesis. To understand the regulatory role of the crgA gene in carotenogenesis, we have used a genetic approach based on the construction of crgA null mutants by gene replacement. Lack of the crgA function provokes the over-accumulation of carotenoids both in the dark and the light. Introduction of the wild-type crgA allele into these mutants restores the wild-type phenotype for carotenogenesis. The high levels of carotenoid accumulation shown by the null crgA mutants are correlated with an increase in the expression of carotenogenic structural genes. These results strongly indicate that crgA acts as a negative regulator of light-inducible carotenogenesis in M. circinelloides.