Tremblay D M, Moineau S
Faculté de Médecine Dentaire, Université Laval, Québec, G1K 7P4, Canada.
Virology. 1999 Mar 1;255(1):63-76. doi: 10.1006/viro.1998.9525.
Streptococcus thermophilus lytic bacteriophage DT1, isolated from a mozzarella whey, was characterized at the microbiological and molecular levels. Phage DT1 had an isometric head of 60 nm and a noncontractile tail of 260 x 8 nm, two major structural proteins of 26 and 32 kDa, and a linear double-stranded DNA genome with cohesive ends at its extremities. The host range of phage DT1 was limited to 5 of the 21 S. thermophilus strains tested. Using S. thermophilus SMQ-301 as a host, phage DT1 had a burst size of 276 +/- 36 and a latent period of 25 min. The genome of phage DT1 contained 34,820 bp with a GC content of 39.1%. Forty-six open reading frames (ORFs) of more than 40 codons were found and putative functions were assigned to 20 ORFs, mostly in the late region of phage DT1. Comparative genomic analysis of DT1 with the completely sequenced S. thermophilus temperate phage O1205 revealed two large homologous regions interspersed by two heterologous segments. The homologous regions consisted of the early replication genes, the late morphogenesis genes, and the lysis cassette. The divergent segments contained the DNA packaging machinery, the major structural proteins, and remnants of a lysogeny module.
从马苏里拉乳清中分离出的嗜热链球菌裂解性噬菌体DT1在微生物学和分子水平上进行了表征。噬菌体DT1具有一个60纳米的等轴头和一个260×8纳米的非收缩性尾部，有两种主要结构蛋白，分子量分别为26 kDa和32 kDa，其线性双链DNA基因组两端带有粘性末端。噬菌体DT1的宿主范围仅限于所测试的21株嗜热链球菌中的5株。以嗜热链球菌SMQ-301作为宿主，噬菌体DT1的裂解量为276±36，潜伏期为25分钟。噬菌体DT1的基因组包含34,820个碱基对，GC含量为39.1%。发现了46个超过40个密码子的开放阅读框（ORF），并为20个ORF赋予了推定功能，这些ORF大多位于噬菌体DT1的晚期区域。将DT1与完全测序的嗜热链球菌温和噬菌体O12进行比较基因组分析，发现有两个大的同源区域，中间穿插着两个异源片段。同源区域由早期复制基因、晚期形态发生基因和裂解盒组成。不同的片段包含DNA包装机制、主要结构蛋白和溶原模块的残余部分。
