Linked Virulence and Fitness of Mycoplasma alligatoris

描述（由申请方提供）：支原体病通常是轻微的，但美洲鳄支原体可引起敏感宿主的急性致死性原发感染。这项工作的目标是解释这种毒力的机制和进化起源。基因组调查表明，M.短吻鳄使用唾液酸酶（NanI）和透明质酸酶（NagH）从宿主细胞聚糖产生用于糖酵解的燃料。其减毒的兄弟种鳄鱼支原体具有NagH但不具有Nanl，因此仅对宿主细胞外基质的损伤不能解释M的特定毒力。鳄鱼虽然nan和nag系统可有助于营养获取的优势，但我们的假设是毒力是那些通过感染共定位的糖苷酶协同作用的结果，其增强宿主CD 44转导的细胞凋亡、坏死和炎症，与观察到的暴发性疾病一致。其推论是，一个适应性增强操纵子如nan可以在水平转移到一个基因组如M后沉淀毒力。鳄鱼的，这是预先适应与nag，一个重要的范例，为出现的病原体。该提案的重点是nan和nag糖苷酶及其在自然简化的小基因组病原体中的相互作用，以及代表微生物病原体和脊椎动物免疫共同进化历史中的重要阶段的宿主。我们的目标是：1）向M展示nan和nag系统的优势。通过转座子介导的敲除和互补其各自途径特有的关键中间酶的基因，确定了反映在Fas（CD 95）、NO和IFN表达中的糖苷酶的细胞病变效应，通过使用体外原代成纤维细胞感染模型灭活和互补nanl和nagH;和3）注释了M. nan基因水平转移对鳄蜥适合度和毒力的影响。crocodyli，如M.鳄鱼本研究结果为M.扬子鳄，并支持水平转移系统的有利选择营养健身作为一种进化机制沉淀一些细菌的毒力。相关性：除了解释M.这项工作将研究CD 44信号在感染过程中如何被细菌调节，这可能为许多侵入性病原体提出新的治疗方式。评估基因组预适应的重要性与适度有利的基因，如透明质酸酶沉淀的严重毒力水平转移后的系统，如nan可能导致预测模型的出现和演变的病原体。

DESCRIPTION (provided by applicant): Mycoplasmosis is usually subtle, but Mycoplasma alligatoris causes acute lethal primary infection of susceptible hosts. The goal of this work is to explain the mechanisms and evolutionary origins of that virulence. A genome survey indicated that M. alligatoris uses sialidase (Nanl) and hyaluronidase (NagH) to generate fuel for glycolysis from host cell glycans. Its attenuated sibling species Mycoplasma crocodyli possesses NagH but not Nanl, so damage to the host's extracellular matrix alone cannot explain the particular virulence of M. alligatoris. While nan and nag systems could contribute to advantages in nutrient acquisition, our hypothesis is that virulence is a consequence of synergy of those glycosidases, co- localized by infection, that potentiates host CD44-transduced apoptosis, necrosis, and inflammation consistent with the fulminant disease observed. The corollary hypothesis is that a fitness-enhancing operon like nan can precipitate virulence after horizontal transfer to a genome like M. crocodyli's which is pre- adapted with nag, a significant paradigm for the emergence of pathogens. This proposal focuses on the nan and nag glycosidases and their interactions in naturally-simplified small-genome pathogens, and hosts which represent a significant stage in the history of co-evolution of microbial pathogens and vertebrate immunity. Our aims are to: 1) Demonstrate the advantages of the nan and nag systems to M. alligatoris for fitness reflected in growth rate and nutrient flux, by transposon-mediated knockout and complementation of genes for the key intermediary enzymes unique to their respective pathways; 2) Define the cytopathic effects of the glycosidases reflected in Fas (CD95), NO, and IFN expression, by inactivation and complementation of nanl and nagH using in vitro primary fibroblast infection models; and 3) Annotate the M. crocodyli genome and model the effects of horizontal transfer of nan genes on fitness and virulence of M. crocodyli as described for M. alligatoris. The results are expected to provide direct evidence of linkage between fitness and virulence factors of M. alligatoris, and support horizontal transfer of systems favorable by selection for nutritional fitness as an evolutionary mechanism precipitating the virulence of some bacteria. Relevance: Beyond explaining the remarkable pathogenicity of M. alligatoris, this work will investigate how CD44 signaling is modulated by bacteria during infection, which could suggest new treatment modalities for many invasive pathogens. Assessing the importance of genome pre-adaptation with modestly advantageous genes like hyaluronidase to precipitation of severe virulence following horizontal transfer of a system like nan could lead to predictive models for the emergence and evolution of pathogens.