Mechanisms of propagation of antibiotic resistance-conferring mobile genetic elements in Enterobacteriaceae and Vibrionaceae

肠杆菌科和弧菌科中赋予抗生素抗性的可移动遗传元件的传播机制

• 批准号: RGPIN-2016-04365
• 负责人: Burrus, Vincent
• 金额: $ 3.21万
• 依托单位: Université de Sherbrooke
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688795
• 关键词: Mechanisms; propagation; antibiotic; resistance; conferring

Knowledge of the genetic determinants and molecular mechanisms that drive the mobility of antibiotic resistance genes is essential to fight the emergence and spread of multidrug resistant bacteria. The integrative and conjugative elements of the SXT/R391 family (SRIs) and the conjugative plasmids of the A/C incompatibility group (ACPs), are major vectors of multidrug resistance genes in pathogenic Enterobacteriaceae and Vibrionaceae. SRIs is responsible for antibiotic resistance of the seventh pandemic lineage of Vibrio cholerae, the etiologic agent of cholera, which remains a major cause of mortality and morbidity on a global scale. Meanwhile, reports associating ACPs with extended-spectrum -lactamases and carbapenemases are unsettlingly rising worldwide in enteric pathogens recovered from the environment, food-producing animals, food products and humans. ACPs also facilitate the propagation of the multidrug resistance-conferring Salmonella Genomic Island 1 (SGI1). Because ACPs and SRIs derive from a common ancestor, they code for highly similar conjugative transfer machineries, which mediate the translocation of genetic material from donor to recipient cells. Currently, the molecular mechanisms mediating these transfers are not well understood. Translocation of ACP and SRI DNA is initiated at the origin of transfer (oriT) by the relaxase TraI and the auxiliary protein MobI, both encoded by ACPs and SRIs. TraI belongs to an atypical family of relaxases, which are predicted HD phosphodiesterases and seems to require a MobI-like auxiliary protein to function, suggesting a completely unique and novel mechanism of conjugative transfer initiation. We anticipate that TraI and MobI are key factors involved in the ACP-mediated transfer of genomic islands such as SGI1.***The main goal of this proposal is to characterize the mechanism of conjugative transfer initiation of ACPs and SRIs, and the molecular interactions between the conjugative machinery of ACPs and genomic islands that they mobilize. More specifically, we propose to identify all the partner proteins that are involved in DNA processing at oriT. Moreover, we aim at discovering the protein translocation signals that allow recognition and secretion of proteins through the type IV secretion system encoded by ACPs and SRIs. We will also functionally map with single-nucleotide accuracy the oriT to determine what specific sequence features promote assembly of a high-order complex at this locus. Finally, we will investigate the interactions between the ACP-encoded relaxosome and genomic islands that are mobilized by ACPs.***Our results will yield fundamental insights about the basic biology ACPs and SRIs, thereby providing the scientific community with strong foundations and new potential molecular targets that could be used for the development of tools aimed at tackling the progression of multidrug resistance.

了解驱动抗生素抗性基因迁移率的遗传决定因素和分子机制对于抵抗多药耐药细菌的出现和传播至关重要。 SXT/R391家族（SRIS）和A/C不兼容组（ACP）的共轭质粒（ACP）的综合元素是致病性肠杆菌科和颤动的多种耐药基因的主要载体。 SRIS负责霍乱的病因学恐怖分子的第七个大流行谱系的抗生素抗性，这仍然是全球范围内死亡率和发病率的主要原因。同时，在全球范围内，从环境中恢复的肠道病原体，食物生产动物，食品和人类中，全球范围内，全球范围内，ACP与扩展​​的光谱 - 乳糖酶和碳纤维酶相关联。 ACP还促进了多药抗性限制沙门氏菌基因组岛1（SGI1）的传播。由于ACP和SRIS源自一个共同的祖先，因此它们为高度相似的共轭转移机器编码，这些转移机器介导了从供体到受体细胞的遗传物质的易位。当前，介导这些转移的分子机制尚不清楚。 ACP和SRI DNA的易位是在通过ACP和SRIS编码的宽松酶TRAI和辅助蛋白MOBI的转移（ORIT）的起源（ORIT）启动的。 TRAI属于非典型的松弛酶家族，该家族是预测的HD磷酸二酯酶，似乎需要一种Mobi样辅助蛋白才能发挥作用，这表明一种完全独特而新颖的结合转移开始机制。我们预计TRAI和MOBI是ACP介导的基因组岛（例如SGI1）转移的关键因素。更具体地说，我们建议识别ORIT中DNA处理的所有伴侣蛋白。此外，我们旨在发现通过ACP和SRIS编码的IV型分泌系统识别蛋白质的蛋白质转运信号。我们还将用单核苷酸精度进行功能绘制ORIT，以确定哪些特定序列特征促进该基因座的高阶复合物的组装。最后，我们将研究由ACP动员的ACP编码的松弛体和基因组岛之间的相互作用。