Gene Silencing and Catabolite Repression in the Archaeon Sulfolobus solfataricus

古细菌硫磺叶菌中的基因沉默和分解代谢物抑制

• 批准号: 0235167
• 负责人: Paul Blum
• 金额: --
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-03-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0235167&HistoricalAwards=false
• 关键词: Gene; Silencing; Catabolite; Repression; Archaeon

Prokaryotes consist of bacteria and archaea. Sulfolobus solfataricus is a member of the crenarchaeal subdivision of the archaea which like eukaryotes catalyze basal transcription using a Pol II-type RNA polymerase, TATA-box promoters and promoter binding proteins. Whether this evolutionary overlap includes regulatory (accessory) transcription components is unknown. This project will focus on gene regulatory mechanisms in archaea and their relationship if any to eukaryotes and bacteria. The Catabolite Repression (CR) system of S. solfataricus will be used as a model of archaeal gene regulation. The CR system exerts coordinate control over the expression of glycosyl hydrolase (GH) genes. Altered GH expression occurs in response to changes in the type of carbon source (catabolite responsiveness), or by mutation at a locus called car. car mutants exhibit reduced GH mRNA levels and an attenuation of catabolite responsiveness suggesting car mediates CR. Since GH mRNA stability is unaffected by CR, regulation must occur at the level of transcript synthesis. Widespread genomic distribution of the affected genes indicates their coordinate expression employs a trans-acting factor possibly encoded or regulated by car. New directed recombination (gene replacement) methods reveal CR exhibits two characteristics of gene silencing, positional repression and action-at-a-distance. Relocation of an affected GH gene to a different chromosomal locus disrupts catabolite responsiveness, while a car-insensitive promoter inserted at a car-regulated locus becomes sensitive (repressed) by car. The main hypothesis of this project is that CR in S. solfataricus employs an ancestral version of eukaryotic transcriptional silencing to control gene expression. This hypothesis will be tested using gene replacement and in vitro transcription methods to identify and characterize sequences used by the CR regulatory mechanism. The project will broaden inclusion of under represented groups and broaden dissemination to enhance scientific and technological understanding by expanding use of a web-based internet site on hyperthermophilic archaea. The anticipated project results will provide insight into basic aspects of archaeal metabolism and the evolutionary origin of gene expression.

原核生物由细菌和古细菌组成。Sulfolobus solfataricus是古细菌中古细菌分支的一员，它像真核生物一样利用Pol ii型RNA聚合酶、TATA-box启动子和启动子结合蛋白催化基础转录。这种进化重叠是否包括调控（辅助）转录成分尚不清楚。本项目将重点研究古细菌的基因调控机制及其与真核生物和细菌的关系。S. solfataricus的分解代谢物抑制（CR）系统将被用作古细菌基因调控的模型。CR系统协调控制糖基水解酶（GH）基因的表达。生长激素表达的改变是由于碳源类型（分解代谢物反应性）的改变，或者是由于car位点的突变。car突变体表现出GH mRNA水平的降低和分解代谢物反应性的减弱，这表明car介导了CR。由于GH mRNA的稳定性不受CR的影响，因此必须在转录物合成水平上进行调节。受影响基因的广泛基因组分布表明，它们的坐标表达采用可能由car编码或调节的反式作用因子。新的定向重组（基因替代）方法表明，CR具有基因沉默、位置抑制和远距离作用两个特征。受影响的生长激素基因重新定位到不同的染色体位点会破坏分解代谢物的反应性，而插入到汽车调节位点的汽车不敏感启动子会被汽车敏感（抑制）。本研究的主要假设是，S. solfataricus的CR采用了祖先版本的真核转录沉默来控制基因表达。这一假设将通过基因替代和体外转录方法进行验证，以鉴定和表征CR调控机制所使用的序列。该项目将扩大代表人数不足的群体的参与范围，并通过扩大使用一个关于嗜热古菌的互联网网站，扩大传播范围，以加强科学和技术的了解。预期的项目结果将为古细菌代谢的基本方面和基因表达的进化起源提供见解。