Lampson B C, Parisi J T
J Bacteriol. 1986 May;166(2):479-83. doi: 10.1128/jb.166.2.479-483.1986.
A naturally occurring constitutive macrolide-lincosamide-streptogramin B (MLS) resistance plasmid, pNE131, from Staphylococcus epidermidis was chosen to study the molecular basis of constitutive expression. Restriction and functional maps of pNE131 are presented along with the nucleotide sequence of ermM, the gene which mediates constitutive MLS resistance. Sharing 98% sequence homology within the 870-base-pair Sau3A-TaqI fragment, ermM appears to be almost identical to ermC, the inducible MLS resistance determinant from S. aureus (pE194). The two genes share nearly identical sequences, except in the 5' promoter region of ermM. Constitutive expression of ermM is due to the deletion of 107 base pairs relative to ermC; the deletion removes critical sequences for attenuation, resulting in constitutive methylase expression.
选择来自表皮葡萄球菌的一种天然存在的组成型大环内酯-林可酰胺-链阳霉素B(MLS)抗性质粒pNE131,来研究组成型表达的分子基础。文中展示了pNE131的限制性内切酶图谱和功能图谱,以及ermM(介导组成型MLS抗性的基因)的核苷酸序列。ermM在870碱基对的Sau3A-TaqI片段内与金黄色葡萄球菌(pE194)的诱导型MLS抗性决定子ermC具有98%的序列同源性,二者似乎几乎相同。除了ermM的5'启动子区域外,这两个基因具有几乎相同的序列。ermM的组成型表达是由于相对于ermC缺失了107个碱基对;该缺失去除了衰减的关键序列,导致甲基化酶组成型表达。