Elucidating the Molecular Mechanisms of Antibiotic Resistance in Acinetobacter baumannii

Abstract

The threat of antibiotic resistance has increasingly become a global issue because of the gradual emergence of multi‐drug resistant (MDR) pathogens. Identifying mechanisms of resistance as well as characterization of attributes deemed beneficial for the survival of the pathogen is vital in contributing to the development of new therapeutics. Acinetobacter baumannii is a gram‐negative opportunistic, nosocomial MDR pathogen that primarily targets immunocompromised patients in medical care facilities around the world. From an assembled bank of clinical isolates of A. baumannii, there is a diverse spectrum of antibiotic resistance patterns, cell motility and biofilm formation represented. Initial RNA sequencing studies implicated the importance of the Gcn5‐related N‐acetyltransferases (GNATs) in facilitating A baumannii resistance to the aminoglycoside class of antibiotics. We aim to determine the role of GNAT proteins to antibiotic resistance in A. baumannii as well as identify which physiological processes are associated with antibiotic resistance. GNATs belong to a superfamily of enzymes that are found in all domains of life and are involved various functions including acetylation of a broad spectrum of substrates and, often times, conferring resistance to antibiotics. We performed structural and functional experiments to understand the mechanisms causing the resistant nature of A. baumannii. Preliminary crystallization studies of the enzyme GNAT 2199 yielded 4 initial conditions suitable for optimal crystal growth. We also conducted a series of enzyme activity assays which revealed that GNATs acetylate various clinically used aminoglycosides. seeking to reveal the natural aminoglycoside substrate for GNAT 2199. Furthermore, cell motility and biofilm assays were used to determine the physiological processes attributed to antibiotic resistance of A. baumannii isolates. Future work entails optimization of the crystallization conditions to produce samples suitable for X‐ray diffraction studies. This will allow us to develop GNAT superfamily structure‐function relationships as well as identify physiological processes of A. baumannii that contribute to antibiotic resistance. In total, this information will be useful for initiating new strategies to control the spread of this bacteria as well as developing new therapeutics to effectively combat this MDR pathogen.Support or Funding InformationNSF No. HRD‐1547757This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.