Young H K, Qumsieh M J, McIntosh M L
Department of Biological Sciences, University of Dundee, UK.
J Antimicrob Chemother. 1994 Nov;34(5):715-25. doi: 10.1093/jac/34.5.715.
Transposon Tn4132, encoding the type Ib trimethoprim-resistant, dihydrofolate reductase, was transposed from the clinical plasmid pUK163 to a small recombinant plasmid pZMR12. Restriction endonuclease and partial sequence analysis of Tn4132 revealed a close relationship to Tn7. The nucleotide sequence of the dhfrIb trimethoprim-resistance gene was determined and the gene and its product were found to share significant homology with the dhfrIa, V, VI and VII plasmid-encoded dihydrofolate reductases. Extensive sequence homology (88%) was observed with the type V dihydrofolate reductase at both the nucleotide and amino acid level. Oligonucleotide probes, distinguishing between the dhfrIb and dhfrV genes, were designed. The discriminatory capabilities of these probes in future epidemiological studies will permit a more accurate determination of the dissemination of these two closely related trimethoprim-resistance genes than has previously been possible.
编码I型耐甲氧苄啶二氢叶酸还原酶的转座子Tn4132从临床质粒pUK163转座至小型重组质粒pZMR12。对Tn4132进行限制性内切酶分析和部分序列分析，发现其与Tn7关系密切。测定了二氢叶酸还原酶Ib型甲氧苄啶抗性基因的核苷酸序列，发现该基因及其产物与二氢叶酸还原酶Ia、V、VI和VII型质粒编码的二氢叶酸还原酶具有显著同源性。在核苷酸和氨基酸水平上，与V型二氢叶酸还原酶均观察到广泛的序列同源性（88%）。设计了区分二氢叶酸还原酶Ib型和V型基因的寡核苷酸探针。这些探针在未来流行病学研究中的鉴别能力将使我们能够比以往更准确地确定这两个密切相关的甲氧苄啶抗性基因的传播情况。
