Molecular Genetics of Rhizobium Nodulation Plasmids

根瘤菌结瘤质粒的分子遗传学

基本信息

批准号：
8757341
负责人：
GRAHAM C WALKER
金额：
$ 42.12万
依托单位：
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
依托单位国家：
美国
项目类别：
财政年份：
1982
资助国家：
美国
起止时间：
1982-07-01 至 2018-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8757341
关键词：
Address Anabolism Antibiotics Antimicrobial Resistance Bacteria Biological Brucella abortus Caulobacter crescentus Cell Cycle Cell Cycle Progression Cell Cycle Regulation Cell Membrane Permeability Cell division Cell physiology Cells Chronic Cysteine DNA Development Employee Strikes Enzymes Fabaceae Gene Expression Genes Genome Glycine Grant Infection Infection Control Integration Host Factors Invaded Investigation Lead Life Mediating Medicago Melilotus Molecular Molecular Genetics Molecular Mechanisms of Action Nodule Pathogenesis Pattern Peptides Physiological Physiological Processes Plant Roots Plants Plasmids Play Polyploidy Process Property Proteobacteria Quality Control RNA RNA Processing Regulation Research Research Support Rhizobium Ribonucleases Ribosomal RNA Ribosomes Role Signal Pathway Sinorhizobium meliloti Small RNA Symbiosis Vitamin B 12 Work antimicrobial peptide base follow-up inhibitor/antagonist insight killings mutant pathogenic bacteria public health relevance response ribonuclease R

项目摘要

DESCRIPTION (provided by applicant): Over the past three decades, research supported by this grant has had a major impact on our understanding of the how Sinorhizobium meliloti invades nodules and establishes the chronic intracellular infection that underlies the symbiosis with its legume host. Our work has also identified common bacterial functions that are important for both symbiotic and pathogenic bacteria to interact with their respective eukaryotic hosts, revealed the missing enzyme in vitamin B12 biosynthesis, and discovered a previously unrecognized, extremely highly conserved RNase. The proposed research addresses critical problems concerning how host antimicrobial peptides modulate S. meliloti's cell cycle and physiology during symbiosis, how the master regulator CtrA acts to control S. meliloti cell cycle progression and terminal differentiation during symbiosis, and how the RNase YbeY exerts its multiple biological roles. Plant-encoded NCR (Nodule Cysteine Rich) antimicrobial peptides play key roles in the striking process in which the bacteria undergo rounds of endoreduplication and terminally differentiate into bacteroids. We will extend our recent work that has offered new molecular insights into how these peptides exert their effects by identifying the biological activities of representative symbiotic NCR and glycine-rich host peptides, investigating the roles of ExoS-ChvI and FeuP-FeuQ signaling pathways in S. meliloti's response to NCR peptides and survival within host plant cells, developing a DNA-based strategy for making nodule NCR and glycine-rich peptides, and continuing to investigate how BacA and other S. meliloti functions provide resistance to the antimicrobial activity of NCR peptides. We have recently gained major insights into how S. meliloti, which has a tripartite genome, controls its cell cycle in the free-living state. A comparison with the well-studied Caulobacter crescentus cell cycle has not only revealed conserved regulatory features common to other ¿-proteobacteria, but also many intriguing differences. We will gain insights into how regulation of the S. meliloti cell cycle has been adapted for symbiosis by elucidating the mechanism by which NCR247 alters cell cycle regulation and blocks cell division, defining the direct transcriptional targets of S. meliloti cel cycle regulator CtrA, and analyzing the role of CtrA in regulating physiological processes relevant to symbiosis. Our characterization of a symbiotically defective S. meliloti mutant led us to discover a previously unidentified RNase, YbeY, which is present in almost all bacteria and plays crucial roles in rRNA processing, 70S ribosome quality control, and small RNA regulation. We will follow up on our recent results by assessing the role of YbeY in B. abortus pathogenesis, completing our investigation of the role of YbeY in the maturation of the 3' terminus of 16S rRNA, gaining additional insights into the mechanism of 70S ribosome quality control mediated by YbeY and RNase R, identifying YbeY's cellular RNA targets, and identifying YbeY inhibitors that could be lead compounds for a potential new class of antibiotics.

描述（由申请人提供）：在过去的三十年中，这项资助支持的研究对我们了解苜蓿中华根瘤菌如何侵入根瘤并建立与其豆科宿主共生的慢性细胞内感染产生了重大影响。还确定了对于共生菌和病原菌与其各自真核宿主相互作用非常重要的常见细菌功能，揭示了维生素 B12 生物合成中缺失的酶，并发现一种以前未被识别的、高度保守的核糖核酸酶。拟议的研究解决了共生期间宿主抗菌肽如何调节苜蓿中华根瘤菌的细胞周期和生理学、共生期间主调节因子CtrA如何控制苜蓿中华根瘤菌细胞周期进程和终末分化的关键问题。，以及 RNase YbeY 如何发挥其多种生物学作用。在细菌经历多轮核内复制并最终分化为类菌的惊人过程中发挥着关键作用，我们将扩展我们最近的工作，通过识别代表性共生 NCR 和类菌的生物活性，为这些肽如何发挥其作用提供了新的分子见解。富含甘氨酸的宿主肽，研究 ExoS-ChvI 和 FeuP-FeuQ 信号通路在苜蓿中华根瘤菌对 NCR 肽的反应和宿主植物细胞内存活中的作用，开发基于 DNA 的策略，用于制造根瘤 NCR 和富含甘氨酸的肽，并继续研究 BacA 和其他苜蓿中华根瘤菌功能如何提供对 NCR 肽的抗菌活性的抗性。与经过充分研究的新月柄杆菌细胞周期的比较不仅揭示了与其他基因组共同的保守调控特征。 ¿ -变形菌，还有许多有趣的差异，我们将深入了解苜蓿中华根瘤菌细胞周期的调节。通过阐明 NCR247 改变细胞周期调节和阻止细胞分裂的机制，定义苜蓿根瘤细胞周期调节剂 CtrA 的直接转录靶标，并分析 CtrA 在调节与共生相关的生理过程中的作用，我们的表征已适应共生。共生缺陷苜蓿苜蓿突变体的研究使我们发现了一种以前未被识别的核糖核酸酶 YbeY，它存在于几乎所有细菌中，并在 rRNA 中发挥着至关重要的作用我们将通过评估 YbeY 在 B. abortus 发病机制中的作用来跟进我们最近的结果，完成我们对 YbeY 在 16S 3' 末端成熟中的作用的研究。 rRNA，进一步了解 YbeY 和 RNase R 介导的 70S 核糖体质量控制机制，识别 YbeY 的细胞 RNA 靶标，并识别 YbeY 抑制剂可能是潜在的新型抗生素的先导化合物。