2023 105 P

Investigating Aminoglycoside Binding in the Acceptor Sites of AAC(6’)-Ig and AAC(6’)-Ih Enzymes

By: Daniel Capule

Department: Chemistry & Biochemistry

Faculty Advisor: Dr. Misty Kuhn

The Gcn-5 related N-acetyltransferase (GNAT) superfamily of enzymes has the ability to acylate a wide variety of substrates and is found in prokaryotes and eukaryotes. Aminoglycoside acetyltransferase (AAC) enzymes are GNATs that acetylate specific amines of various aminoglycoside antibiotics, which are typically used to treat Gram-negative bacterial infections. Previous studies on the AAC(6’)-Ig and AAC(6’)-Ih enzymes kinetically characterized these enzymes and found they can acetylate numerous aminoglycosides. These aminoglycosides have a common deoxystreptamine core, with glycosidic bonds ((4,5) and (4,6)) to different heterocycles, all of which can have different arrangements of functional groups. To explore how these substrates may be bound in the acceptor pocket of the -Ig and -Ih enzymes, we performed computational studies to analyze which residues are important for recognizing substrates and binding via molecular docking in Molecular Operating Environment (MOE) software. Given the large number of results generated by molecular docking, we developed a method to sort poses by proximity to the presumed location of the acetyl donor to simulate likely bound configurations important for transfer of an acyl group. Our preliminary results show substrate-residue interactions are indeed substrate-specific, as residues interact with substrates’ functional groups in distinct patterns despite these substituents’ diverse configurations on the common deoxystreptamine core across substrates.