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Hexose degradation pathways and their transcriptional regulation in halophilic archaea

嗜盐古菌中己糖降解途径及其转录调控

基本信息

批准号：
286542984
负责人：
Professor Dr. Peter Schönheit
金额：
--
依托单位：
Institut für Allgemeine Mikrobiologie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/286542984?language=en
关键词：
Hexose degradation pathways their transcriptional

项目摘要

Haloferax volcanii utilizes the hexoses D-glucose and D-galactose and the deoxyhexose L-rhamnose as carbon and energy source. First studies of our group indicate that glucose is degraded via a semiphosphorylative Entner-Doudoroff (spED) pathway and D-galactose via a De Ley-Doudoroff (DD) pathway. The transport of glucose and galactose, several key enzymes of the degradation pathways, and their transcriptional regulation have not been studied in detail so far. Also, the degradation of L-rhamnose in haloarchaea has not been investigated so far. Adjacent to the gene of glucose dehydrogenase, the first enzyme of glucose degradation, we identified a gene encoding a putative transcriptional regulator PyrE1, which is homologous to the unusual transcriptional regulators of purine- and pyrimidine metabolism of few gram-positive bacteria. Further, we have identified in the gene cluster of galactose degradation pathway - a putative IclR like transcriptional regulator. First studies indicate a function of both regulators as transcriptional activators of glucose and galactose degradation pathways, respectively. In the galactose gene cluster we identified an ABC transporter, likely involved in galactose transport. Haloarcula marismortui also contained - in genomic neighbourhood of glucose dehydrogenase gene, a PyrE1 homologous transcriptional regulator and an ABC transporter, likely involved in glucose transport. During growth of H. volcanii on L-rhamnose we found an inducible L-rhamnose dehydrogenase activity indicating the operation of a non phosphorylative L-rhamnose degradation pathway. In the genome of H. volcanii we identified two gene clusters encoding hypothetical rhamnose degradation pathways each including genes for ABC transporter and IclR like transcriptional regulators. In the planned grant proposal we will investigate transport, the degradation pathways and their transcriptional regulation of D-glucose, D-galactose and L-rhamnose in haloarchaea. The involvement of ABC transporters in sugar transport will be analysed using deletion mutants and by characterization of the sugar binding proteins. The key enzymes of sugar degradation pathways and the transcriptional regulators PyrE1 and IclR in haloarchaea will be studied in detail. The studies will contribute to the understanding of unusual sugar degradation pathways in haloarchaea and of novel types of transcriptional regulators in the domain of archaea.

Haloferax volcanii利用己糖D-葡萄糖和D-半乳糖以及脱氧己糖L-鼠李糖作为碳源和能源。本课题组的初步研究表明，葡萄糖通过半磷酸化Entner-Doudoroff（spED）途径降解，D-半乳糖通过De Ley-Doudoroff（DD）途径降解。葡萄糖和半乳糖的转运及其转录调控是葡萄糖降解途径中的关键酶，目前还没有详细的研究。此外，到目前为止还没有研究过L-鼠李糖在盐古菌中的降解。邻近的葡萄糖脱氢酶，葡萄糖降解的第一个酶的基因，我们确定了一个基因编码一个假定的转录调节PyrE 1，这是同源的嘌呤和嘧啶代谢的少数革兰氏阳性细菌的不寻常的转录调节。此外，我们已经在半乳糖降解途径的基因簇中鉴定了一种推定的IclR样转录调节因子。第一研究表明，这两个监管机构作为葡萄糖和半乳糖降解途径的转录激活剂的功能，分别。在半乳糖基因簇中，我们确定了ABC转运蛋白，可能参与半乳糖转运。海生盐囊藻在葡萄糖脱氢酶基因的基因组附近还含有一个PyrE 1同源转录调节因子和一个ABC转运蛋白，可能参与葡萄糖的转运。在H. volcanii对L-鼠李糖的作用，我们发现诱导型L-鼠李糖脱氢酶活性，表明非磷酸化L-鼠李糖降解途径的作用。在H. volcanii中，我们鉴定了两个编码假设的鼠李糖降解途径的基因簇，每个基因簇包括ABC转运蛋白和IclR样转录调节因子的基因。在计划的资助提案中，我们将研究盐古菌中D-葡萄糖，D-半乳糖和L-鼠李糖的运输，降解途径及其转录调控。将使用缺失突变体和糖结合蛋白的表征分析ABC转运蛋白在糖转运中的参与。本文将对盐古菌糖降解途径中的关键酶及转录调控因子PyrE 1和IclR进行深入研究。这些研究将有助于了解盐古菌中不寻常的糖降解途径和古菌域中新型的转录调节因子。