Yu C E, Ferretti J J
Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
Mol Gen Genet. 1991 Dec;231(1):161-8. doi: 10.1007/BF00293833.
Bacteriophage T12 is the prototype phage carrying the streptococcal erythrogenic toxin A (speA) gene. To examine more closely the phages involved in lysogenic conversion, we examined 300 group A streptococcal strains, and identified and isolated two new phages that carry the speA gene. The molecular sizes of these phage genomes were between 32 and 40 kb, similar to that of phage T12 (35 kb). However, as ascertained by restriction analysis, the physical maps of the new phage genomes were different from phage T12 and from each other. Hybridization analysis also showed that all of these phages were only partially related to one another and the speA gene was always located close to the phage attachment site. Additionally, colony hybridization showed that whereas phage T12 or one of its close relatives is the most common phage associated with the group A streptococci, phage 49 has a much stronger association with the speA gene. A defective phage was also found following pulsed field gel electrophoresis of total phage DNA. This phage appears to be a resident of strain T25(3)c and is found only following induction of a T25(3)c lysogen. Restriction enzyme analysis of the isolated defective phage DNA suggests that it is the source of the submolar amounts of DNA previously found in association with phage T12 digestion patterns. Additionally, the defective phage may serve as the site of integration of the speA gene-carrying phages described above.
噬菌体T12是携带链球菌致热外毒素A（speA）基因的原型噬菌体。为了更深入地研究参与溶原性转化的噬菌体，我们检测了300株A群链球菌菌株，鉴定并分离出两种携带speA基因的新噬菌体。这些噬菌体基因组的分子大小在32至40 kb之间，与噬菌体T12（35 kb）相似。然而，通过限制性分析确定，新噬菌体基因组的物理图谱与噬菌体T12不同，且彼此之间也不同。杂交分析还表明，所有这些噬菌体彼此之间仅部分相关，且speA基因总是位于靠近噬菌体附着位点的位置。此外，菌落杂交显示，虽然噬菌体T12或其近亲之一是与A群链球菌相关的最常见噬菌体，但噬菌体49与speA基因的关联更强。在对总噬菌体DNA进行脉冲场凝胶电泳后，还发现了一种缺陷噬菌体。这种噬菌体似乎是菌株T25(3)c的常驻噬菌体，仅在诱导T25(3)c溶原菌后才能发现。对分离出的缺陷噬菌体DNA进行限制性酶切分析表明，它是先前在与噬菌体T12消化模式相关联时发现的亚摩尔量DNA的来源。此外，缺陷噬菌体可能是上述携带speA基因的噬菌体的整合位点。
