UMR Micalis, INRA, AgroParisTech, Université Paris-Saclay, UMR1319, Jouy-en-Josas, France.
Center of Bioinformatics, Biostatistics and Integrative Biology (C3BI), Institut Pasteur, USR 3756 CNRS, 75015, Paris, France.
mSphere. 2019 Jul 10;4(4):e00310-19. doi: 10.1128/mSphere.00310-19.
Commensal and generally harmless in healthy individuals, causes opportunistic infections in immunocompromised patients. Plasmid-cured strain VE14089, derived from sequenced reference strain V583, is widely used for functional studies due to its improved genetic amenability. Although strain VE14089 has no major DNA rearrangements, with the exception of an ∼20-kb integrated region of pTEF1 plasmid, the strain presented significant growth differences from the V583 reference strain of our collection (renamed VE14002). In the present study, genome sequencing of strain VE14089 identified additional point mutations. Excision of the integrated pTEF1 plasmid region and sequential restoration of wild-type alleles showing nonsilent mutations were performed to obtain the VE18379 reference-derivative strain. Recovery of the growth ability of the restored VE18379 strain at a level similar to that seen with the reference strain points to GreA and Spx as bacterial fitness determinants. Virulence potential in and intestinal colonization in mouse demonstrated host adaptation of the VE18379 strain equivalent to VE14002 host adaptation. We further demonstrated that deletion of the 16.8-kb variable region of the locus recapitulates the key role of Epa decoration in host adaptation, providing a genetic system to study the role of specific -variable regions in host adaptation independently of other genetic variations. strain VE14089 was derived from V583 cured of its plasmids. Although VE14089 had no major DNA rearrangements, it presented significant growth and host adaptation differences from the reference strain V583 of our collection. To construct a strain with better fitness, we sequenced the genome of VE14089, identified single nucleotide polymorphisms (SNPs), and repaired the genes that could account for these changes. Using this reference-derivative strain, we provide a novel genetic system to understand the role of the variable region of in the enterococcal lifestyle.
在健康个体中，共生且通常无害，但在免疫功能低下的患者中会引起机会性感染。从测序参考菌株 V583 衍生而来的无质粒的 VE14089 菌株由于其遗传可操作性得到改善而被广泛用于功能研究。尽管 VE14089 菌株没有主要的 DNA 重排，除了 pTEF1 质粒的一个约 20kb 的整合区域外，但与我们收集的 V583 参考菌株相比，该菌株表现出明显的生长差异（重新命名为 VE14002）。在本研究中，对 VE14089 菌株的基因组测序发现了其他点突变。通过切除整合的 pTEF1 质粒区域并依次恢复显示非沉默突变的野生型等位基因，获得了 VE18379 参考衍生菌株。恢复的 VE18379 菌株的生长能力恢复到与参考菌株相似的水平，这表明 GreA 和 Spx 是细菌适应性的决定因素。在 和小鼠肠道定植中的毒力潜力表明，VE18379 菌株的宿主适应性与 VE14002 宿主适应性相当。我们进一步证明，缺失 基因座的 16.8kb 可变区域可重现 Epa 修饰在宿主适应性中的关键作用，提供了一个遗传系统来独立于其他遗传变异研究特定 -可变区在宿主适应性中的作用。VE14089 菌株源自无质粒的 V583。尽管 VE14089 菌株没有主要的 DNA 重排，但与我们收集的 V583 参考菌株相比，它表现出明显的生长和宿主适应性差异。为了构建具有更好适应性的菌株，我们对 VE14089 菌株的基因组进行了测序，确定了单核苷酸多态性（SNP），并修复了可能导致这些变化的基因。使用该参考衍生菌株，我们提供了一个新的遗传系统来理解 可变区在肠球菌生活方式中的作用。
