中文摘要：近年来，大肠杆菌K1荚膜特异性噬菌体已有报道，但其宿主识别的分子机制尚不清楚。本文研究了新型k1特异性噬菌体PNJ1809-36与其宿主菌DE058的相互作用。利用转座子突变文库筛选受体相关基因。基因缺失、裂解曲线测定、菌斑形成试验、吸附试验和脂多糖（LPS）对噬菌体的抑制试验表明，荚膜多糖（CPS）是PNJ1809-36最初吸附到大肠杆菌DE058的第一个受体，而LPS是噬菌体不可逆结合的第二个受体。外核倒数第二半乳糖被鉴定为LPS的特异性结合区域。通过抗体阻断试验、荧光标记和高效凝胶渗透色谱，鉴定噬菌体PNJ1809-36的尾部蛋白ORF261为CPS的受体结合蛋白。鉴于此，本文提出了噬菌体PNJ1809-36在大肠杆菌DE058上识别过程的模型：噬菌体PNJ1809-36尾部蛋白ORF261识别并吸附到K1荚膜，然后K1荚膜被部分降解，暴露了噬菌体PNJ1809-36识别的LPS活性位点。该模型提供了K1特异性噬菌体与其宿主细菌之间的分子机制。
重点：据推测，CPS是长尾病毒科K1特异性噬菌体的主要受体。近年来，又报道了一种新型肌病毒科K1特异性噬菌体，但其宿主识别机制尚不清楚。本文研究了一种新型K1噬菌体PNJ1809-36与其宿主菌大肠杆菌DE058之间的相互作用。发现噬菌体最初吸附在ORF261介导的K1荚膜上，然后与LPS的倒数第二个半乳糖结合，开启感染过程。
外文摘要：K1 capsule-specific phages of Escherichia coli have been reported in recent years, but the molecular mechanism involved in host recognition of these phages remains unknown. In this study, the interactions between PNJ1809-36, a new K1-specific phage, and its host bacterium, E. coli DE058, were investigated. A transposon mutation library was used to screen for receptor-related genes. Gene deletion, lysis curve determination, plaque formation test, adsorption assay, and inhibition assay of phage by lipopolysaccharide (LPS) showed that capsular polysaccharide (CPS) was the first receptor for the initial adsorption of PNJ1809-36 to E. coli DE058 and that LPS was a secondary receptor for the irreversible binding of the phage. The penultimate galactose in the outer core was identified as the specific binding region on LPS. Through antibody blocking assay, fluorescence labeling and high-performance gel permeation chromatography, the tail protein ORF261 of phage PNJ1809-36 was identified as the receptor-binding protein on CPS. Given these findings, we propose a model for the recognition process of phage PNJ1809-36 on E. coli DE058: the phage PNJ1809-36 tail protein ORF261 recognizes and adsorbs to the K1 capsule, and then the K1 capsule is partially degraded, exposing the active site of LPS which is recognized by phage PNJ1809-36. This model provides insight into the molecular mechanisms between K1-specific phages and their host bacteria.
   IMPORTANCE It has been speculated that CPS is the main receptor of K1-specific phages belonging to Siphoviridae. In recent years, a new type of K1-specific phage belonging to Myoviridae has been reported, but its host recognition mechanisms remain unknown. Here, we studied the interactions between PNJ1809-36, a new type of K1 phage, and its host bacterium, E. coli DE058. Our research showed that the phage initially adsorbed to the K1 capsule mediated by ORF261 and then bound to the penultimate galactose of LPS to begin the infection process.
外文关键词：phage；Escherichia coli；receptor；LPS；K1 capsule
作者：Gong, QW；Wang, XH；Huang, HS；Sung, Y；Qian, XJ；Xue, F；Ren, JL；Dai, JJ；Tang, F
作者单位：Nanjing Agr Univ；China Pharmaceut Univ
期刊名称：JOURNAL OF VIROLOGY
期刊影响因子：4.501
出版年份：2021
出版刊次：18
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