Characterization of mutations contributing to sulfathiazole resistance in Escherichia coli.
Characterization of mutations contributing to sulfathiazole resistance in Escherichia coli.
复制标题
大肠杆菌中磺胺噻唑耐药性突变的表征。
DOI：
10.1128/aac.42.1.88
复制
发表时间：
1998
影响因子：
4.9
通讯作者：
Nichols,BP
中科院分区：
文献类型：
--
作者：
Vedantam,G;Guay,GG;Austria,NE;Doktor,SZ;Nichols,BP
通过P1转导，将两种不同的大肠杆菌耐硫噻唑二氢蝶呤合成酶（DHPS）定位于folpp1。核苷酸序列分析表明，每个菌株的folpmutation是相同的。单个C→T转变导致64位氨基酸上Pro→Ser取代。用野生型folp代替突变型folp显著降低了对磺胺噻唑的抗性水平，但没有消除它，这表明存在一个额外的突变，该突变有助于两株菌株对磺胺噻唑的抗性。将突变等位基因转移到野生型背景导致菌株对磺胺噻唑只有低水平的抗性，这表明抗性DHPS的存在本身并不足以解释这些菌株对磺胺噻唑的整体抗性。杆菌。对其中一株菌株中扩增的次级耐药决定因子sur的进一步鉴定，确定其为先前鉴定的双环霉素耐药决定因子cr，是膜结合多药耐药反转运蛋白家族的一员。另一种导致磺胺噻唑耐药性的突变sux也已被发现，并已被证明影响这些超嘌呤菌株对腺嘌呤敏感性的组氨酸反应。
A sulfathiazole-resistant dihydropteroate synthase (DHPS) present in two different laboratory strains ofEscherichia colirepeatedly selected for sulfathiazole resistance was mapped tofolPby P1 transduction. ThefolPmutation in each of the strains was shown to be identical by nucleotide sequence analysis. A single C→T transition resulted in a Pro→Ser substitution at amino acid position 64. Replacement of the mutantfolPalleles with wild-typefolPsignificantly reduced the level of resistance to sulfathiazole but did not abolish it, indicating the presence of an additional mutation(s) that contributes to sulfathiazole resistance in the two strains. Transfer of the mutantfolPallele to a wild-type background resulted in a strain with only a low level of resistance to sulfathiazole, suggesting that the presence of the resistant DHPS was not in itself sufficient to account for the overall sulfathiazole resistance in these strains ofE. coli. Additional characterization of an amplified secondary resistance determinant,sur, present in one of the strains, identified it as the previously identified bicyclomycin resistance determinantbcr, a member of a family of membrane-bound multidrug resistance antiporters. An additional mutation contributing to sulfathiazole resistance,sux, has also been identified and has been shown to affect the histidine response to adenine sensitivity displayed by thesepurUstrains.