Regulation of Photosynthetic Electron Transport Genes in Chlamydomonas Chloroplasts

衣藻叶绿体中光合电子传递基因的调控

• 批准号: 0091020
• 负责人: David Stern
• 金额: $ 44万
• 依托单位: Boyce Thompson Institute Plant Research
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-15 至 2006-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0091020&HistoricalAwards=false
• 关键词: Regulation; Photosynthetic; Electron; Transport; Genes

0091020 David SternChloroplasts, the site of photosynthesis, are derived from a cyanobacterial ancestor and have progressively transferred most of their genetic information to the nucleus. Because chloroplasts contain up to 5,000 proteins, today the vast majority are of nuclear origin. Among these proteins are a myriad which are required for correct expression of the genes which remain in the chloroplast. This project focuses on nucleus encoded proteins which regulate messenger RNA lifetime in the green alga Chlamydomonas reinhardtii, as well as on how chloroplast ribosomes recognize the site at which protein synthesis must be initiated. This project will further earlier analyses which revealed that at least 5 nuclear genes encode products which affect the stability of petD mRNA, which encodes subunit IV of the cytochrome b6/f complex, an essential protein for photosynthesis. One of these genes, Mcd1, has been cloned and the details of its interaction with the petD mRNA will be elucidated. Another gene whose product may form part of a multiprotein complex with Mcd1 will also be studied. This gene, mcd4, was identified through a genetic screen based on photosynthetic capability. Mcd4 has been targeted because it appears to have unique attributes with respect to other nuclear genes involved in chloroplast biogenesis. The second aspect of the project concerns translation initiation, and in particular the interaction between the initiator tRNA and the nucleotide upstream of the translation initiation codon of petA, which encodes cytochrome f. The generality of this interaction will be investigated, as well as the role of the so-called Shine-Dalgarno sequence, whose functionality in bacterial protein synthesis is well-established, but whose role in chloroplasts is somewhat controversial and clearly variable. Overall, this project will elucidate mechanisms of communication between different compartments of eukaryotic cells, a fundamental issue in understanding intracellular regulation.

0091020光合作用位点David Sternchloroplasts源自蓝细菌祖先，并逐渐将其大部分遗传信息转移到细胞核中。由于叶绿体含有多达5,000种蛋白质，因此今天的绝大多数都是核源物。这些蛋白质中有无数，这是正确表达保留在叶绿体中的基因所必需的。该项目的重点是编码蛋白质的核，该蛋白质调节绿色藻类衣原体Reinhardtii中的信使RNA寿命，以及叶绿体核糖体如何识别必须启动蛋白质合成的位点。该项目将进一步分析，该项目表明，至少5个核基因编码影响PETD mRNA稳定性的产物，PETD mRNA编码了细胞色素B6/F复合物的亚基IV，这是一种光合作用的必需蛋白质。这些基因之一MCD1被克隆，其与PETD mRNA相互作用的细节将被阐明。还将研究另一个可能构成MCD1多蛋白复合物的一部分的基因。该基因MCD4是通过基于光合作用能力的遗传筛选来鉴定的。 MCD4之所以成为目标，是因为它似乎与叶绿体生物发生有关的其他核基因具有独特的属性。该项目的第二个方面涉及翻译起始，尤其是启动器tRNA与PETA翻译起始密码子上游的核苷酸之间的相互作用，该密码子编码细胞色素f。将研究这种相互作用的一般性，以及所谓的Shine-Dalgarno序列的作用，其在细菌蛋白质合成中的功能是完善的，但其在叶绿体中的作用有些争议且明显可变。总体而言，该项目将阐明真核细胞不同隔室之间通信的机制，这是理解细胞内调节的基本问题。