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Transcriptional regulation, differential secretion, and eco-physiological function(s) of levansucrase in the plant pathogen, Pseudomonas syringae

植物病原体丁香假单胞菌中果聚糖蔗糖酶的转录调控、差异分泌和生态生理功能

基本信息

批准号：
107805781
负责人：
Professor Dr. Matthias S. Ullrich
金额：
--
依托单位：
Department of Life Sciences and Chemistry
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2009
资助国家：
德国
起止时间：
2008-12-31 至 2011-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/107805781?language=en
关键词：
Transcriptional regulation differential secretion eco

项目摘要

The plant-borne disaccharide, sucrose, is a readily available carbon source for plant pathogens, bacteria of the oral cavity, and microbes associated with bio-ethanol production. These microorganisms use the extra-cellular enzyme, levansucrase, to release glucose from sucrose and to polymerize fructosyl residues into the branched polymer levan. Our previous studies showed that two levansucrases of the gramnegative bacterium, Pseudomonas syringae, i) are expressed in a temperaturedependent manner; ii) showed distinct export and secretion patterns distinguishable from any classical protein secretion pathway; and iii) led to an accumulation of levan in ‘storage compartments’ of biofilms. Herein, it will be determined how levansucrase gene expression is regulated, how the enzymes are transported via inner and outer membrane, and what the actual physiological role of levan formation is in context of carbon metabolism. The role of a newly identified regulator, LscR, and its interaction with three repressors, HexR, MvaT, and MvaU, will be investigated. The export/secretion pathways of both levansucrases will be identified and characterized. The hypothesis that levan formation might be a form of bacterial ‘waste disposal’ for later carbon recycling will be tested, and the individual enzymatic activities of both iso-enzymes will be elucidated.

植物源性二糖蔗糖是植物病原体、口腔细菌以及与生物乙醇生产相关的微生物的现成碳源。这些微生物利用胞外酶、果聚糖蔗糖酶从蔗糖中释放葡萄糖，并将果糖基残基聚合成支链聚合物果聚糖。我们之前的研究表明，革兰氏阴性细菌丁香假单胞菌的两种果聚糖蔗糖酶，i) 以温度依赖性方式表达； ii) 显示出与任何经典蛋白质分泌途径不同的独特输出和分泌模式； iii) 导致左聚糖在生物膜的“储存室”中积累。在此，将确定如何调节果聚糖蔗糖酶基因表达，如何通过内膜和外膜运输酶，以及在碳代谢背景下果聚糖形成的实际生理作用是什么。我们将研究新鉴定的调节因子 LscR 的作用及其与三种阻遏蛋白 HexR、MvaT 和 MvaU 的相互作用。两种果聚糖蔗糖酶的输出/分泌途径将被鉴定和表征。果聚糖形成可能是细菌“废物处理”的一种形式，用于以后的碳回收，这一假设将得到测试，并且两种同工酶的单独酶活性将得到阐明。