Acinetobacter baumannii is nowadays a relevant nosocomial pathogen characterized by multidrug resistance (MDR) and concomitant difficulties to treat infections. OmpA is the most abundant A. baumannii outer membrane (OM) protein, and is involved in virulence, host-cell recognition, biofilm formation, regulation of OM stability, permeability and antibiotic resistance. OmpA members are two‐domain proteins with an N‐terminal eight‐stranded β‐barrel domain with four external loops (ELs) interacting with the environment, and a C‐terminal periplasmic domain binding non‐covalently to the peptidoglycan. Here, we combined data from genome sequencing, phylogenetic and multilocus sequence analyses from 975 strains/isolates of the Acinetobacter calcoaceticus / Acinetobacter baumannii complex (ACB), 946 from A. baumannii , to explore ompA microevolutionary divergence. Five major ompA variant groups were identified (V1 to V5) in A. baumannii , encompassing 52 different alleles coding for 23 different proteins. Polymorphisms were concentrated in five regions corresponding to the four ELs and the C‐terminal end, and provided evidence for intra‐genic recombination. ompA variants were not randomly distributed across the A . baumannii phylogeny, with the most frequent V1(lct)a1 allele found in most clonal complex 2 (CC2) strains and the second most frequent V2(lct)a1 allele in the majority of CC1 strains. Evidence was found for assortative exchanges of ompA alleles not only between separate A . baumannii lineages, but also different ACB species. The overall results have implications for A. baumannii evolution, epidemiology, virulence and vaccine design.

中文翻译：

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鲍曼不动杆菌主要外膜蛋白OmpA的微进化。

鲍曼不动杆菌 是当今一种相关的医院病原体，其特征在于多药耐药性（MDR）和随之而来的治疗感染的困难。OmpA是最丰富的鲍曼不动杆菌外膜（OM）蛋白，并参与毒力，宿主细胞识别，生物膜形成，调节OM稳定性，通透性和抗生素抗性。OmpA成员是一个具有两个末端结构域的蛋白质，其N末端八链β桶状结构域具有四个与环境相互作用的外部环（EL），一个C末端周质结构域与肽聚糖非共价结合。在这里，我们结合了来自975株不弯曲不动杆菌/菌株的基因组测序，系统发育和多基因座序列分析的数据/ 鲍曼不动杆菌 复合物（ACB），946从鲍曼不动杆菌，探索的ompA微进化分歧。在鲍曼不动杆菌中鉴定出五个主要的ompA变体组（V1至V5），包括编码23种不同蛋白质的52个不同等位基因。多态性集中在与四个EL和C末端相对应的五个区域，为基因内重组提供了证据。ompA变种不是随机分布在整个A上。鲍曼尼 系统发育，在大多数克隆复合物2（CC2）菌株中发现频率最高的V1（lct）a1等位基因，在大多数CC1菌株中发现频率第二高的V2（lct）a1等位基因。发现的证据表明，不仅在单独的A之间存在ompA等位基因的相互交换。鲍曼氏谱系，但也有不同的ACB物种。总体结果对鲍曼不动杆菌的进化，流行病学，毒力和疫苗设计具有影响。