Puig Montserrat, Gironés Rosina
Microbiology (Reading). 1999 Jul;145 ( Pt 7):1661-1670. doi: 10.1099/13500872-145-7-1661.
Very few data are available on the molecular biology of Bacteroides fragilis bacteriophages, which have been considered in several studies as indicators of faecal contamination. Phage B40-8, initially isolated from an urban sewage sample using a strain of B. fragilis (HSP40) isolated from a clinical specimen, was chosen in this study as a prototype for morphological and molecular studies. Like most of the phages infective for B. fragilis, B40-8 belongs to the Siphoviridae family. Its genome has been found to be a double-stranded DNA molecule, of approximately 51.7 kb, containing a rather low percentage (38.9 mol%) of G + C. The ends of the molecule appeared not to be cohesive but permuted, with a terminal redundancy of 7.3%. A genomic map was constructed. Three major proteins (MP) out of 15 peptides in the SDS-PAGE profile were selected for N-terminal sequencing. From these data, degenerate probes were designed to locate the ORFs in the genomic map. Immunodetection by electron microscopy revealed that MP1 and MP3 were structural proteins of the phage head and that MP2 was a constituent of the tail. A genomic library of the phage was prepared, and a clone including the MP2 ORF was identified and sequenced.
关于脆弱拟杆菌噬菌体的分子生物学，目前可获得的数据非常少，在多项研究中，它们被视为粪便污染的指标。噬菌体B40 - 8最初是从城市污水样本中分离出来的，使用的是从临床标本中分离出的脆弱拟杆菌菌株（HSP40），在本研究中被选作形态学和分子研究的原型。与大多数感染脆弱拟杆菌的噬菌体一样，B40 - 8属于长尾噬菌体科。已发现其基因组是一个双链DNA分子，约51.7 kb，G + C含量相当低（38.9摩尔%）。分子末端似乎没有粘性，而是重排的，末端冗余度为7.3%。构建了基因组图谱。从SDS - PAGE图谱中的15种肽中选择了三种主要蛋白质（MP）进行N端测序。根据这些数据，设计了简并探针来定位基因组图谱中的开放阅读框（ORF）。通过电子显微镜进行免疫检测发现，MP1和MP3是噬菌体头部的结构蛋白，而MP2是尾部的组成部分。制备了噬菌体的基因组文库，并鉴定和测序了一个包含MP2开放阅读框的克隆。
