Major

Chemistry

Anticipated Graduation Year

2020

Access Type

Open Access

Abstract

The Gcn5-related N-acetyltransferase (GNAT) superfamily is responsible for diverse biological functions and is critically important in cellular and metabolic processes in all kingdoms of life. GNATs transfer an acetyl-group from an active donor, typically acetyl-coenzyme A (AcCoA), to a primary amine of an acceptor substrate. Members of this family are well known for their roles in aminoglycoside antibiotic resistance, histone modification, protein acetylation, xenobiotic metabolism, and other cellular processes.1, 2 A small subset of bacterial GNAT enzymes have been studied and characterized both structurally and functionally, but the function of the vast majority remains unknown. Most of the reported 3D crystallographic structures of GNATs contain no acceptor substrate bound in their active sites. We previously screened the PA3944 protein against a panel of potential substrates and found the enzyme exhibited the highest activity toward aspartame, polymyxin B and colistin (polymyxin E).3 Our project involves the synthesis of molecular analogs of previously identified functionally relevant acceptor substrates that will be co-crystallized with GNAT-PA3944, in particular simplified derivatives of polymyxin B including NANMO and AAB, and we have shown that NANMO is as efficient as polymyxin B as a substrate. The ligand-bound crystallographic structures will provide insight into the structural features of the active site that are involved in substrate recognition and advance our understanding of types of substrates recognized by this enzyme of unknown function. Syntheses of NANMO and AAB will be described, along with modeling and substrate efficiency.

Faculty Mentors & Instructors

Dr. Daniel P Becker, Professor, Department of Chemistry and Biochemistry, Loyola University Chicago

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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Synthesis of GNAT PA3944 Substrate Analogs

The Gcn5-related N-acetyltransferase (GNAT) superfamily is responsible for diverse biological functions and is critically important in cellular and metabolic processes in all kingdoms of life. GNATs transfer an acetyl-group from an active donor, typically acetyl-coenzyme A (AcCoA), to a primary amine of an acceptor substrate. Members of this family are well known for their roles in aminoglycoside antibiotic resistance, histone modification, protein acetylation, xenobiotic metabolism, and other cellular processes.1, 2 A small subset of bacterial GNAT enzymes have been studied and characterized both structurally and functionally, but the function of the vast majority remains unknown. Most of the reported 3D crystallographic structures of GNATs contain no acceptor substrate bound in their active sites. We previously screened the PA3944 protein against a panel of potential substrates and found the enzyme exhibited the highest activity toward aspartame, polymyxin B and colistin (polymyxin E).3 Our project involves the synthesis of molecular analogs of previously identified functionally relevant acceptor substrates that will be co-crystallized with GNAT-PA3944, in particular simplified derivatives of polymyxin B including NANMO and AAB, and we have shown that NANMO is as efficient as polymyxin B as a substrate. The ligand-bound crystallographic structures will provide insight into the structural features of the active site that are involved in substrate recognition and advance our understanding of types of substrates recognized by this enzyme of unknown function. Syntheses of NANMO and AAB will be described, along with modeling and substrate efficiency.