Golubkov V I, Reichardt W, Boitsov A S, Iontova I M, Malke H, Totolian A A
Mol Gen Genet. 1982;187(2):310-5. doi: 10.1007/BF00331135.
By using electron microscopy of self-annealed DNA and restriction enzyme analysis, we have compared the physical maps of two group A streptococcal plasmids associated with conventional MLS resistance (pEL1; 20 Md) and zonal lincomycin resistance (pSM10419; 15 Md). Of their monomeric molecules, about 40% and 60%, respectively, are occupied by identical non-tandem inverted repeats containing sequences specifying putative replication functions. Sequence homology also exists between their resistance determinants which are located in unique DNA. Moreover, homology between additional regions of unknown function is so extensive and restriction fragment arrangement so similar that, formally, pSM10419 can be considered a deletion variant of pEL1. The results suggest that MLS and zonal lincomycin resistance have the same biochemical basis (i.e. methylation of 23S ribosomal RNA) and differ only quantitatively in the inducible control systems.
通过对自身退火DNA进行电子显微镜观察和限制性内切酶分析，我们比较了与传统大环内酯-林可酰胺-链阳菌素B（MLS）耐药性相关的两种A群链球菌质粒（pEL1；20 Md）和区域林可霉素耐药性相关的质粒（pSM10419；15 Md）的物理图谱。在它们的单体分子中，分别约40%和60%被相同的非串联反向重复序列占据，这些序列包含指定假定复制功能的序列。它们位于独特DNA中的耐药决定簇之间也存在序列同源性。此外，未知功能的其他区域之间的同源性非常广泛，限制性片段排列也非常相似，因此从形式上看，pSM10419可被视为pEL1的缺失变体。结果表明，MLS耐药性和区域林可霉素耐药性具有相同的生化基础（即23S核糖体RNA的甲基化），只是在诱导控制系统中存在数量差异。
