Acta Veterinaria et Zootechnica Sinica ›› 2020, Vol. 51 ›› Issue (5): 1138-1148.doi: 10.11843/j.issn.0366-6964.2020.05.025

• BASIC VETERINARY MEDICINE • Previous Articles     Next Articles

Study on β-lactamase and Its Action Mode of Staphylococcus aureus Isolated from Cows in Ningxia

MA Qiang1, YANG Rui2, WAN Jiahong1, CHANG Jiawei1, WEI Yanqin1, WANG Guiqin1*   

  1. 1. College of Agriculture, Ningxia University, Yinchuan 750021, China;
    2. College of Veterinary Medicine, Jilin University, Changchun 130062, China
  • Received:2019-11-08 Online:2020-05-25 Published:2020-05-16

Abstract: This study aimed to study the evolution and structural characteristics of β-lactamase produced by Staphylococcus aureus (SA) and its action mode in Ningxia province. Antimicrobial susceptibility test and PCR were used to detect the resistance and drug resistance genes of five β-lactams respectively; the evolution analysis and structure function prediction of β-lactamase BlaZ were made by bioinformatics; the mode of action of BlaZ was analyzed by molecular docking and dynamic simulation. The results showed that the resistance rate of Penicillins was significantly higher than Cephalosporin's; the detection rate of blaZ gene was 82.37% and the detection rate of blaZTEM-1 gene, which was rarely reported in SA, was 26.05%. According to evolutionary analysis, BlaZ belongs to A-type β-lactamase and contains 63 important trace residues under evolutionary pressure. Meanwhile, molecular docking showed that BlaZ is easy to combine with Penicillins, Avibatan, what's more, formed stable. The results of molecular dynamics simulation showed that the structural flexibility of BlaZ was less than that of TEM-1 and TEM-52, in which there was a difference in the flexibility of Ω-loop region (P<0.05) and it could affect the antibiotic binding. Thus, there was a positive correlation between the flexibility of the region and the binding activity; the structural stability of BlaZ was significantly different (P<0.05) when it was combined with Ampicillin and Ceftiofur, respectively. The BlaZ produced by SA in Ningxia is a A-type β-lactamase. In addition, blaZTEM-1 gene was detected from those strains. The bind-ing activity of BlaZ to Penicillins and Avibactam is higher than that of Cephalosporin, and the structural flexibility of Ω-loop region is an important factor affecting the binding activity.

Key words: Staphylococcus aureus, β-lactamase, action mode, bioinformatics, molecular simulation

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