Study of a Natural Mutant SHV-Type β -Lactamase, SHV-104, from Klebsiella pneumoniae.
Study of a Natural Mutant SHV-Type β -Lactamase, SHV-104, from Klebsiella pneumoniae.
复制标题
来自克雷伯氏菌肺炎的天然突变体SHV型β-lactamase，SHV-104。
DOI：
10.1155/2014/548656
复制
发表时间：
2014
影响因子：
3.4
通讯作者：
Mercuri PS
中科院分区：
文献类型：
--
作者：
Ben Achour N;Belhadj O;Galleni M;Ben Moussa M;Mercuri PS
肺炎克雷伯菌 ML2011 是一种多重耐药菌株，从突尼斯军事医院（突尼斯）分离出来。肺炎克雷伯菌 ML2011 的最低抑制浓度由 Etest 测定。分离物的粗提物含有四种不同的 β-内酰胺酶，pI 为 5.5、7.3、7.6 和 8.6。通过转化和接合实验仅转移了pI 7.3和pI 8.6的β-内酰胺酶。通过 PCR 和测序对这些基因进行分子表征。染色体 β-内酰胺酶是 TEM (pI 5.5) 和 SHV-1 (7.6)。 CTX-M-28 (pI 8.6) 和名为 SHV-104 (pI 7.3) 的 SHV 新变体由位于 50 kb 高度接合质粒上的 bla 基因编码。 SHV-104 β-内酰胺酶在大肠杆菌中产生并纯化。确定了其活性概况。与SHV-1相比，SHV-104含有一个突变，R202S。除头孢噻肟外，它们的动力学参数相似。对 SHV-104 的预测结构的分析表明，R202S 突变抑制了 SHV-1 中存在的盐桥。因此，蛋白质的整体灵活性增加，并可能改善头孢噻肟的水解。我们可以得出结论，肺炎克雷伯菌ML2011菌株的多重耐药表型主要与CTX-M-28的产生有关，因为SHV-104具有窄谱活性。
Klebsiella pneumoniae ML2011, a multiresistant isolate, was isolated from the Military Hospital of Tunis (Tunisia). The determination of the minimal inhibitory concentrations exhibited by K. pneumoniae ML2011 was performed by Etest. The crude extract of the isolates contains four different β-lactamases with pI 5.5, 7.3, 7.6, and 8.6. Only the β-lactamases with pI 7.3 and pI 8.6 were transferred by transformation and conjugation experiment. Molecular characterization of these genes was performed by PCR and sequencing. The chromosomal β-lactamases are TEM (pI 5.5) and SHV-1 (7.6). CTX-M-28 (pI 8.6) and the novel variant of SHV named SHV-104 (pI 7.3) were encoded by bla gene located on a 50 kb highly conjugative plasmid. The SHV-104 β-lactamase was produced in E. coli and purified. Its profile of activity was determined. Compared to SHV-1, SHV-104 contains one mutation, R202S. Their kinetic parameters were similar except for cefotaxime. The analysis of the predicted structure of SHV-104 indicated that the R202S mutation suppresses a salt bridge present in SHV-1. Therefore, the overall flexibility of the protein increased and might improve the hydrolysis of cefotaxime. We can conclude that the multiresistant phenotype of K. pneumoniae ML2011 strain is mainly linked to the production of CTX-M-28 since SHV-104 possesses a narrow spectrum of activity.