Coleman D C, Sullivan D J, Russell R J, Arbuthnott J P, Carey B F, Pomeroy H M
Department of Microbiology, University of Dublin, Trinity College, Republic of Ireland.
J Gen Microbiol. 1989 Jun;135(6):1679-97. doi: 10.1099/00221287-135-6-1679.
A new group of serotype F bacteriophages of Staphylococcus aureus has been found which mediates the simultaneous triple-lysogenic conversion of enterotoxin A, staphylokinase and beta-lysin. The phages were recovered fro methicillin-resistant strains of S. aureus isolated in Irish hospitals between 1971 and 1988 and from strain PS42-D, which has been used as the propagating strain for the S. aureus typing phage 42D since before 1965. The molecular mechanism of triple conversion mediated by three of these phages was determined by molecular cloning, restriction endonuclease site mapping and hybridization analysis, and compared with the mechanism of beta-lysin and staphylokinase conversion mediated by the serotype F, double-converting phase phi 13. THe genetic determinants mediating expression of enterotoxin A (entA) and staphylokinase (sak) were cloned from the DNA of the triple-converting phage and expression of the cloned determinants detected in Escherichia coli and S. aureus. The entA and sak determinants were closely linked in the phage DNA adjacent to the phage attachment site (attP) in each case and furthermore, the sak determinant of phage phi 13 was also located near its attP. The restriction maps of the entA-, sak- and attP-containing DNA regions of the three triple-converting phages were very similar to each other and to the corresponding sak- and attP- containing DNA region of phage phi 13. Hybridization analysis using a cloned beta-lysin determinant (hlb) and cloned attP-containing DNA fragments as probes demonstrated that beta-lysin conversion mediated by the triple-converting phages and phage phi 13 was caused by insertional inactivation of the chromosomally encoded hlb determinant by orientation-specific integration of phage DNA following lysogenization.
已发现一组新的金黄色葡萄球菌F血清型噬菌体，它们介导肠毒素A、葡萄球菌激酶和β-溶血素的同时三重溶原性转化。这些噬菌体是从1971年至1988年在爱尔兰医院分离出的耐甲氧西林金黄色葡萄球菌菌株以及菌株PS42-D中获得的，自1965年以前，PS42-D一直用作金黄色葡萄球菌分型噬菌体42D的增殖菌株。通过分子克隆、限制性内切酶位点图谱分析和杂交分析，确定了其中三种噬菌体介导三重转化的分子机制，并与F血清型双转化噬菌体phi 13介导的β-溶血素和葡萄球菌激酶转化机制进行了比较。从三重转化噬菌体的DNA中克隆了介导肠毒素A（entA）和葡萄球菌激酶（sak）表达的遗传决定因素，并在大肠杆菌和金黄色葡萄球菌中检测了克隆决定因素的表达。在每种情况下，entA和sak决定因素在噬菌体DNA中与噬菌体附着位点（attP）相邻紧密相连，此外，噬菌体phi 13的sak决定因素也位于其attP附近。三种三重转化噬菌体的entA、sak和含attP的DNA区域的限制性图谱彼此非常相似，并且与噬菌体phi 13的相应含sak和attP的DNA区域相似。使用克隆的β-溶血素决定因素（hlb）和克隆的含attP的DNA片段作为探针进行的杂交分析表明，三重转化噬菌体和噬菌体phi 13介导的β-溶血素转化是由于溶原化后噬菌体DNA的定向特异性整合导致染色体编码的hlb决定因素插入失活所致。
