Correlation between the number of Pro-Ala repeats in the EmrA homologue of Acinetobacter baumannii and resistance to netilmicin, tobramycin, imipenem and ceftazidime.
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.
Department of Biology and Ecology, Jędrzej Sniadecki Academy of Physical Education and Sport in Gdańsk, Gdańsk, Poland; Plasmids and Microorganisms Collection University of Gdańsk, Gdańsk, Poland.
Alicja
A
Nowak-Zaleska
Department of Physical Chemistry, Gdańsk University of Technology, Gdańsk, Poland.
Miłosz
M
Wieczór
Department of Physical Chemistry, Gdańsk University of Technology, Gdańsk, Poland.
Jacek
J
Czub
Department of Physical Chemistry, Gdańsk University of Technology, Gdańsk, Poland.
Łukasz
Ł
Nierzwicki
Department of Molecular Biotechnology and Microbiology, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland. Electronic address: romkotlo@pg.gda.pl.
Roman
R
Kotłowski
Department of Microbiology, Nicolaus Copernicus University in Toruń, Collegium Medicum of L. Rydygier in Bydgoszcz, Bydgoszcz, Poland.
Agnieszka
A
Mikucka
Department of Microbiology, Nicolaus Copernicus University in Toruń, Collegium Medicum of L. Rydygier in Bydgoszcz, Bydgoszcz, Poland.
Eugenia
E
Gospodarek
D000151:Acinetobacter Infections; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D002442:Ceftazidime / Q000494:pharmacology; D004151:Dipeptides / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D009428:Netilmicin / Q000494:pharmacology; D014031:Tobramycin / Q000494:pharmacology
D001426:Bacterial Proteins; D004151:Dipeptides; D008565:Membrane Proteins; C077168:emrA protein, Bacteria; D009428:Netilmicin; D015378:Imipenem; D002442:Ceftazidime; D014031:Tobramycin
3D model; Acinetobacter baumannii; Antibiotic resistance; CAP01997; EmrA homologue