Identification and analysis of Chlamydomonas mutants with defects in chlorophyll synthesis

叶绿素合成缺陷衣藻突变体的鉴定与分析

• 批准号: 98772029
• 负责人: Professor Dr. Bernhard Grimm
• 金额: --
• 依托单位: Arbeitsgruppe Pflanzenphysiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/98772029?language=en
• 关键词: Identification; analysis; Chlamydomonas; mutants; defects

Mutants of Chlamydomonas reinhardtii tolerate genetic lesions in chlorophyll synthesis as long as accumulating chlorophyll precursors cannot generate photooxidative stress. Therefore, knock-out mutants for genes in chlorophyll synthesis can grow in darkness on an additional carbon source and be analyzed, while corresponding plant mutants would be embryo-lethal. We continue to screen a collection of dark-grown interesting photosensitive mutants with brown, yellow and yellow-green pigmentation, which are all specified by diverse accumulating chlorophyll precursors that photosensitize these mutants and disable them to grow strictly photoautotrophically. The main objective is the detailed analysis of three mutants with either deleted GUN4 or HEM4 genes or displaying an accumulation of Mg protoporphyrin monomethylester indicating an impaired cyclase reaction. The expression of genes as well as enzyme activities of tetrapyrrole biosynthesis will be studied in these mutants allowing a prediction of transcriptional and posttranslational regulatory mechanisms of Chlamydomonas affecting regulation of tetrapyrrole biosynthesis and photosynthesis, which might be different from those of previously analyzed vascular plants. Other studies include assessments of (i) LHC expression during increasing light intensities in response to impaired chlorophyll biosynthesis and (ii) protein interactions among enzymes and factors of the Mg branch as a prerequisite for efficient substrate channeling and avoidance of tetrapyrrole-dependent photooxidative stress.

只要累积叶绿素前体就无法产生光氧化应激，叶绿素合成中遗传遗传病变的突变体可耐受叶绿素合成中的遗传病变。因此，叶绿素合成基因的敲除突变体可以在附加的碳源上在黑暗中生长，并进行分析，而相应的植物突变体将是胚胎致死的。我们继续筛选出具有棕色，黄色和黄色绿色色素沉着的深色有趣的光敏突变体的集合，这些突变体均由各种积累的叶绿素前体来指定，这些叶绿素前体光敏性突变体并使它们禁用它们以严格的光自养生。主要目的是对三个具有删除的Gun4或Hem4基因的突变体的详细分析或显示Mg原源性单甲基酯的积累，表明循环酶反应受损。这些突变体将研究基因的表达以及四吡咯生物合成的酶活性，允许预测影响四磷酸生物合成和光合作用的四磷酸化调节的转录和翻译后调节机制，这可能与以前分析的工厂不同。其他研究包括评估（i）在响应叶绿素生物合成受损的光强度增加的（i）LHC表达的情况下，以及（ii）酶之间的蛋白质相互作用以及MG分支的因素，作为有效的底物通道的先决条件，并避免了四吡咯取决于依赖于四吡咯的光（依赖于四）的光（避免）。