Department of Infectious Diseases, College of Veterinary Medicine, Brain Korea 21 for Veterinary Science, Seoul National University, Seoul, S Korea.
BMC Microbiol. 2011 Feb 4;11:29. doi: 10.1186/1471-2180-11-29.
The aim of this study was to analyze the significance of leucine to proline substitution at position 138(Leu138Pro) on the hydrolysis of penicillin and ampicillin that we identified in the blaSHV gene of clinical Escherichia coli swine isolate.
Kinetic analysis of the mutant proteins showed that K(m) value of the purified L138P mutant was comparatively higher than SHV-1, SHV-33 and SHV-33(L138P) enzyme for penicillin and ampicillin. Docking simulation of the SHV-1 and SHV-(L138P) enzymes also confirmed that β-lactamases preferred penicillin to ampicillin and the SHV-1 had a higher binding affinity for antibiotics compared to the SHV-(L138P) and other mutants.
Our result demonstrated that L138P has a reduced role in penicillin and ampicillin hydrolyzing properties of SHV β-lactamases. These naturally occurring mutations rendering reduced function of the existing protein could trigger the emergence or acquisition of more effective alternative mechanisms for β-lactam hydrolysis.
本研究旨在分析我们在临床大肠杆菌猪分离株 blaSHV 基因中发现的第 138 位亮氨酸到脯氨酸取代（Leu138Pro）对青霉素和氨苄青霉素水解的意义。
突变蛋白的动力学分析表明，与 SHV-1、SHV-33 和 SHV-33（L138P）酶相比，纯化的 L138P 突变体的 K(m) 值对青霉素和氨苄青霉素的亲和力较低。SHV-1 和 SHV-（L138P）酶的对接模拟也证实了β-内酰胺酶更喜欢青霉素而不是氨苄青霉素，与 SHV-（L138P）和其他突变体相比，SHV-1 对抗生素的结合亲和力更高。
我们的结果表明，L138P 在 SHV β-内酰胺酶对青霉素和氨苄青霉素的水解特性中作用降低。这些导致现有蛋白质功能降低的自然发生突变可能会引发或获得更有效的替代β-内酰胺水解机制。
