qnrB, another plasmid-mediated gene for quinolone resistance
qnrB, another plasmid-mediated gene for quinolone resistance
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DOI：
10.1128/aac.50.4.1178-1182.2006
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发表时间：
2006-04-01
影响因子：
4.9
通讯作者：
Hooper, DC
中科院分区：
文献类型：
--
作者：
Jacoby, GA;Walsh, KE;Hooper, DC
在南印度分离的肺炎克雷伯菌菌株的编码CTX-M-15 β -内酰胺酶的质粒中发现了一种新的质粒介导的喹诺酮类药物耐药基因qnrB。它与原始qnr（现在的qnrA）基因或最近描述的qnrS基因的氨基酸同源性不到40%，但与它们一样，编码一种属于五肽重复家族的蛋白质。携带qnrB的菌株对所有喹诺酮类药物均表现出低水平耐药性。该基因已被克隆到带有多组氨酸标签的表达载体上，纯化达到>= 95%的同源性。只需5pm的QnrB-His(6)就能保护纯化的DNA旋切酶免受2 μ g/ml （6 μ M）环丙沙星的抑制。qnrB基因已在来自美国的Citrobacter koseri， Enterobacter cloarae和Escherichia coli分离株中检测到，与SHV-12 β -内酰胺酶有关，编码的产物与印度品种（现为QnrB1）有5个氨基酸差异。qnrB基因已在Orf1005附近的一些质粒中发现，但不是全部，并且与已知染色体基因匹配的开放阅读框相关。这表明它也是由一种未知细菌来源的质粒获得的。
A novel plasmid-mediated quinolone resistance gene, qnrB, has been discovered in a plasmid encoding the CTX-M-15 beta-lactamase from a klebsiella pneumoniae strain isolated in South India. It has less than 40% amino acid identity with the original qnr (now qnrA) gene or with the recently described qnrS but, like them, codes for a protein belonging to the pentapeptide repeat family. Strains with qnrB demonstrated low-level resistance to all quinolones tested. The gene has been cloned in an expression vector attaching a polyhistidine tag, which facilitated purification to >= 95% homogeneity. As little as 5 pM of QnrB-His(6) protected purified DNA gyrase against inhibition by 2 mu g/ml (6 mu M) ciprofloxacin. With a PCR assay qnrB has been detected in Citrobacter koseri, Enterobacter cloarae, and Escherichia coli isolates from the United States, linked to SHV-12 beta-lactamase and coding for a product differing in five amino acids from the Indian (now QnrB1) variety, The qnrB gene has been found near Orf1005 in some, but not all, plasmids and in association with open reading frames matching known chromosomal genes, suggesting that it too was acquired by plasmids from an as-yet-unknown bacterial source.