Smith M D, Hazum S, Guild W R
J Bacteriol. 1981 Oct;148(1):232-40. doi: 10.1128/jb.148.1.232-240.1981.
A mutation to tetracycline sensitivity in a resistant strain of Streptococcus pneumoniae was shown by several criteria to be due to a point mutation in the conjugative omega (cat-tet) element found in the chromosomes of strains derived from BM6001, a clinical strain resistant to tetracycline and chloramphenicol. Strains carrying the mutation were transformed back to tetracycline resistance with the high efficiency of a point marker by donor deoxyribonucleic acids from its ancestral strain and from nine other clinical isolates of pneumococcus and by deoxyribonucleic acids from group D Streptococcus faecalis and group B Streptococcus agalactiae strains that also carry conjugative tet elements in their chromosomes. It was not transformed to resistance by tet plasmid deoxyribonucleic acids from either gram-negative or gram-positive species, except for one that carried transposon Tn916, the conjugative tet element present in the chromosomes of some S. faecalis strains. The results showed that the tet determinants in conjugative elements of several streptococcal species share a high degree of deoxyribonucleic acid sequence homology and suggested that they differ from other tet genes.
通过多种标准表明，肺炎链球菌耐药菌株中对四环素敏感性的突变是由于在源自BM6001（一种对四环素和氯霉素耐药的临床菌株）的菌株染色体中发现的接合型ω（cat - tet）元件发生了点突变。携带该突变的菌株能够被其原始菌株以及其他9株肺炎链球菌临床分离株的供体脱氧核糖核酸，还有来自D组粪肠球菌和B组无乳链球菌菌株（它们的染色体中也携带接合型tet元件）的脱氧核糖核酸，以点标记的高效率转化回四环素抗性。除了携带转座子Tn916（一些粪肠球菌菌株染色体中存在的接合型tet元件）的一种质粒外，革兰氏阴性或革兰氏阳性物种的tet质粒脱氧核糖核酸均不能将其转化为抗性。结果表明，几种链球菌物种接合元件中的tet决定簇具有高度的脱氧核糖核酸序列同源性，并表明它们与其他tet基因不同。
