Monod M, Denoya C, Dubnau D
J Bacteriol. 1986 Jul;167(1):138-47. doi: 10.1128/jb.167.1.138-147.1986.
We initiated a study of pIM13, a multicopy, macrolide-lincosamide-streptogramin B (MLS) plasmid first isolated from a strain of Bacillus subtilis and described by Mahler and Halvorson (J. Gen. Microbiol. 120:259-263, 1980). The copy number of this plasmid was about 200 in B. subtilis and 30 in Staphylococcus aureus. The MLS resistance determinant of pIM13 was shown to be highly homologous to ermC, an inducible element on the S. aureus plasmid pE194. The product of the pIM13 determinant was similar in size to that of ermC and immunologically cross-reactive with it. The MLS resistance of pIM13 was expressed constitutively. The complete base sequence of pIM13 is presented. The plasmid consisted of 2,246 base pairs and contained two open reading frames that specified products identified in minicell extracts. One was a protein of 16,000 molecular weight, possibly required for replication. The second was the 29,000-molecular-weight MLS resistance methylase. The regulatory region responsible for ermC inducibility was missing from pIM13, explaining its constitutivity. The remainder of the pIM13 MLS determinant was nearly identical to ermC. The ends of the region of homology between pIM13 and pE194 were associated with hyphenated dyad symmetries. A segment partially homologous to one of these termini on pIM13 and also associated with a dyad was found in pUB110 near the end of a region of homology between that plasmid and pBC16. The entire sequence of pIM13 was highly homologous to that of pE5, an inducible MLS resistance plasmid from S. aureus that differs from pIM13 in copy control.
我们开展了对pIM13的研究，这是一种多拷贝的大环内酯-林可酰胺-链阳菌素B（MLS）质粒，最初从一株枯草芽孢杆菌中分离得到，并由马勒和哈尔沃森进行了描述（《普通微生物学杂志》120:259 - 263，1980年）。该质粒在枯草芽孢杆菌中的拷贝数约为200，在金黄色葡萄球菌中为30。pIM13的MLS抗性决定簇被证明与ermC高度同源，ermC是金黄色葡萄球菌质粒pE194上的一个可诱导元件。pIM13决定簇的产物在大小上与ermC的产物相似，并且与其存在免疫交叉反应。pIM13的MLS抗性是组成型表达的。本文给出了pIM13的完整碱基序列。该质粒由2246个碱基对组成，包含两个开放阅读框，它们所指定的产物在小细胞提取物中得到了鉴定。一个是分子量为16000的蛋白质，可能是复制所必需的。第二个是分子量为29000的MLS抗性甲基化酶。pIM13中缺少负责ermC诱导性的调控区域，这解释了其组成型表达的原因。pIM13的MLS决定簇的其余部分与ermC几乎相同。pIM13和pE194之间同源区域的末端与间断的二重对称相关。在pUB110中靠近该质粒与pBC16同源区域末端的位置发现了一个与pIM13上这些末端之一部分同源且也与一个二重对称相关的片段。pIM13的整个序列与pE5的序列高度同源，pE5是来自金黄色葡萄球菌的一个可诱导MLS抗性质粒，在拷贝控制方面与pIM13不同。
