Correlation between the number of Pro–Ala repeats in the EmrA homologue of Acinetobacter baumannii and resistance to netilmicin, tobramycin, imipenem and ceftazidime. (December 2016)

• Record Type: Journal Article
• Authors: Nowak-Zaleska, Alicja; Wieczór, Miłosz; Czub, Jacek; Nierzwicki, Łukasz; Kotłowski, Roman; Mikucka, Agnieszka; Gospodarek, Eugenia
• Is Part Of: Journal of global antimicrobial resistance. Volume 7(2016:Dec.)
• Page Start: 145
• Page End: 149
• Publication Date: 2016-12
• Subjects: Acinetobacter baumannii -- CAP01997 -- EmrA homologue -- 3D model -- Antibiotic resistance; Drug resistance -- Periodicals; Drug resistance -- Periodicals; Drug resistance; Periodicals; 616.9041
• DOI: 10.1016/j.jgar.2016.09.004
• Languages: English
• ISSNs: 2213-7165

Abstract

Highlights: CAP01997 protein is the A. baumannii homologue of the E. coli transporter EmrA. Significant correlation between susceptibility to four antibiotics and number of Pro–Ala repeats in CAP01997. New mechanism of antibiotic resistance based on extension of Pro–Ala repeats in the N-terminal fragment of CAP01997. Abstract: Acinetobacter baumannii coccobacilli are dangerous to patients in intensive care units because of their multidrug resistance to antibiotics, developed mainly in the past decade. This study aimed to examine whether there is a significant correlation between the number of Pro–Ala repeats in the CAP01997 protein, the EmrA homologue of A. baumannii, and resistance to antibiotics. A total of 79 multidrug-resistant A. baumannii strains isolated from patients were analysed. Resistance to antibiotics was determined on Mueller–Hinton agar plates using the Kirby–Bauer disk diffusion method. The number of CCTGCA repeats encoding Pro–Ala repeats in CAP01997 was determined by PCR and capillary electrophoresis. The 3D models of CAP01997 containing Pro–Ala repeats were initially generated using RaptorX Structure Prediction server and were assembled with EasyModeller 4.0. The models were embedded in a model bacterial membrane based on structural information from homologous proteins and were refined using 100-ns molecular dynamics simulations. The results of this research show significant correlation between susceptibility to netilmicin, tobramycin and imipenem and the number of repeated Pro–Ala sequences in the CAP01997 protein, a homologue of the Escherichia coli transporter EmrA. Predicted structures suggest potential mechanisms that confer drug resistance by reshaping the cytoplasmic interface between CAP01997 protein and the critical component of the multidrug efflux pump homologous to EmrB. Based on these results, we can conclude that the CAP01997 protein, an EmrA homologue of A. baumannii, confers resistance to netilmicin, tobramycin and imipenem, depending on the number of Pro–Ala repeats.