Transcriptional Regulation of Carbon Utilization in the Hyperthermophilic Archaeon Sulfolobus Solfataricus

9604000 Blum这项研究旨在确定已经进化的机制，以克服在极端温度下对基因表达调控施加的固有生物物理限制，并进一步澄清了亚门的进化位置。 基于rDNA序列比较的系统发育研究表明，该属与真杆菌属和真核生物都有较远的亲缘关系。尽管真核生物与真核生物在遗传学上不同，但它们的转录组分表现出显著的相似性。 然而，目前尚不清楚这种相似性是否延伸到DNA序列和调节转录的因子。 最近发现的分解代谢物抑制（CR）反应的好氧，超嗜热硫化叶菌solfataricus将被用作一个模型系统，研究基因调控的古菌。 该系统的一个组成部分称为CR-I由碳利用酶水平的变化和它们各自的转录物引起的增长上的层次结构的唯一的碳和能源。 CR-I调节malA（麦芽糖酶）、malE（外切葡糖酸酶）和多顺反子malL簇的表达。 由于基因组分析表明，这些靶基因中有几个是物理上不相连的，因此CR-I使用全局调节机制来控制基因表达。 此外，CR-I似乎上调malA和malE，而下调malL。 这项研究将确定CR-I调节是否发生在转录起始水平，并将确定CR-I控制mal基因表达所需的顺式和反式作用因子。 这项研究的结果将阐明好氧极端嗜热菌如何调节基因表达以选择性消耗碳。 虽然超嗜热菌存在于两个古菌亚群，广古菌和泉古菌中，但它们的rDNAs异常根深蒂固，表明它们是最早出现在地球上的生物之一。 因此，这项研究可能会提供额外的洞察基因表达的进化起源。 基于核糖体DNA（rDNA）序列比较的系统发育研究发现了一组独特的生物体，称为真杆菌属，与真杆菌属和真核生物都有远亲关系。 尽管真核生物与真核生物在遗传学上不同，但它们的转录组分表现出显著的相似性。 然而，目前尚不清楚这种相似性是否延伸到DNA序列和调节转录的因子。超嗜热菌Sulfulobus solfataricus将被用作研究古细菌基因调控的模型系统。预期的结果将阐明如何有氧hyperthermophilia调节基因表达在极端温度下，并将提供洞察古菌hyperthermophilia代谢和基因表达的进化起源的基本方面。

9604000 Blum This research seeks to identify mechanisms which have evolved to overcome the inherent biophysical constraints imposed on the regulation of gene expression at extreme temperatures, as well as further clarify the evolutionary position of the Archaea. Phylogenetic studies based on comparison of rDNA sequences have shown that the Archaea are distantly related to both Eubactria and Eukaryotes. Although Archaea are phylogentically distinct from Eukaryotes, their transcriptional components exhibit remarkable similarity. However, it is not know whether this similarity extends to DNA sequences and factors that regulate transcription. The recently discovered Catabolite Repression (CR) response in the aerobic, hyperthermophile Sulfulobus solfataricus will be used as a model system to study gene regulation in archaeons. One component of this system termed CR-I consists of variations in levels of carbon utilization enzymes and their respective transcripts elicited by growth on a hierarchy of sole carbon and energy sources. CR-I regulates expression of malA (maltase), malE (exogluconase) and the polycistronic malL cluster. Since genomic analysis indicates that several of these target genes are physically unlinked, CR-I uses a global regulatory mechanism to control gene expression. Moreover, CR-I appears to up regulate malA and malE while down regulating malL. This research will determine if CR-I regulation occurs at the level of transcription initiation and will identify the cis and trans-acting factors necessary for CR-I control of mal gene expression. The results of this research will clarify how aerobic hyperthermophilic Archaea regulate gene expression for the selective consumption of carbon. While hyperthermophiles are are present in both archaeal sub-divisions, the Euryarchaeota and the Crenarchaeota, their rDNAs are unusually deeply rooted suggesting that they were among the first organisms to appear on earth. This research therefore may provide additional insight into the ev olutionary origin of gene expression. Phylogenetic studies based on comparison of ribosomal DNA (rDNA) sequences have led to the discovery of a distinct group of organisms termed the Archaea which are distantly related to both Eubactria and Eukaryotes. Although Archaea are phylogentically distinct from Eukaryotes, their transcriptional components exhibit remarkable similarity. However, it is not know whether this similarity extends to DNA sequences and factors that regulate transcription. The hyperthermophile Sulfulobus solfataricus will be used as a model system to study gene regulation in archaeons. The anticipated results will clarify how aerobic hyperthermophilic Archaea regulate gene expression at extreme tempertures, and will provide insight into basic aspects of archaeal hyperthermophilic metabolism and the evolutionary origin of gene expression.