R-Factor-Mediated Resistance to Sulfonamides by a Plasmid-Borne, Drug-Resistant Dihydropteroate Synthase
R-Factor-Mediated Resistance to Sulfonamides by a Plasmid-Borne, Drug-Resistant Dihydropteroate Synthase
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R 因子介导的质粒携带的耐药二氢蝶酸合酶对磺胺类药物的耐药性
DOI：
10.1128/aac.9.1.49
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发表时间：
1976
影响因子：
4.9
通讯作者：
O. Sköld
中科院分区：
文献类型：
--
作者：
O. Sköld
有证据表明，参与叶酸形成的二氢蝶酸合酶存在附加体特异性变体。由于质粒携带的酶表现出对磺胺抑制的敏感性降低，并且可以转移，同时对该药物具有抗性，因此提出在某些情况下靶酶的二倍体可能是R因子介导的对磺胺类药物的抗性机制。获得了两种证据。其中之一是通过R因子R1 dr19介导磺胺耐药性来拯救染色体二氢蝶酸合酶损伤的细菌突变体的温度敏感性。另一个证据是通过测定R−和R+细菌提取物中的二氢蝶酸形成活性发现的。发现携带R1dr19的细胞含有一种酶活性，这种酶活性对磺胺抑制的敏感性远远低于R−细胞的相应活性。
Evidence was found for the existence of an episome-specified variant of the enzyme dihydropteroate synthase involved in folic acid formation. Since the plasmid-borne enzyme showed a decreased susceptibility for sulfonamide inhibition and was transferable together with resistance to this drug, it is proposed that diploidy for the target enzyme in some cases could be the mechanism of R-factor-mediated resistance to sulfonamides. Two types of evidence were obtained. One was the rescue from temperature sensitivity of bacterial mutants with a lesion in the chromosomal dihydropteroate synthase by the R factor R1dr19 mediating sulfonamide resistance. The other evidence was found by the determination of dihydropteroate forming activity in extracts from R− and R+ bacteria. Cells harboring R1dr19 were found to contain an enzyme activity which was far less susceptible to sulfonamide inhibition than the corresponding activity from R− cells.