Aminoglycosides are broad-spectrum antibiotics used for treatment of serious bacterial infections, including the deadly tuberculosis and those accompanying AIDS, cystic fibrosis, and cancer. The emergence of pathogens resistant to these drugs represents a major threat to public health and underscores the need for new antimicrobial agents.
In Aim 1, we propose to utilize aminoglycoside-modifying enzymes of the aminoglycoside acetyltransferase (AAC) family in conjunction with a newly developed 6'-N-acylation protecting group-free chemical methodology (i) to generate in vitro libraries of new and more potent N-acylated aminoglycoside antibiotics, and (ii) to develop aminoglycoside probes that will serve as baits for identification of novel therapeutic protein targets/pathways for these antibiotics. Our chemoenzymatic and chemical strategies offer an effective solution to the following problems: (i) there are no existing general synthetic methodologies for the creation of N-acylated aminoglycosides, and (ii) there are no efficient methods to chemically modify specific amine groups on an aminoglycoside that contains a series of chemically identical amines. A few existing examples that use solely chemical syntheses are too demanding on research time and cost and are limited to very specific cases.
In Aim 2, we propose biochemical and structural studies of the mechanism of action and inhibition of a major determinant of aminoglycoside resistance in extensively drug-resistant strains of M. tuberculosis (XDR-TB). We expect this work to (i) advance the basic understanding of AG resistance of a variety of pathogenic bacteria, including M. tuberculosis, and (ii) provide a potential solution to overcome the aminoglycoside resistance problem in majority of XDR- TB. Relevance to public health: We expect that this work will contribute to the development of novel antibiotics with a potential to combat existing and newly emerging drug-resistant bacteria.

Public Health Relevance

The proposed research is relevant to public health as an improved understanding of aminoglycoside- resistance enzymes is expected to lead to the discovery and development of new drugs and also in identifying drug targets. This research will enable us to better handle the problem of resistance of infectious bacteria to aminoglycoside antibiotics. The proposed research will have a major impact in two ways: (1) our novel chemical and chemoenzymatic methodologies for the rapid and facile regio- selective N-acylation of aminoglycosides will greatly reduce the cost and effort generally associated with such modifications, and (2) our study of the mechanism of action and inhibition of the major determinant of aminoglycosdie resistance in extensively drug-resistant M. tuberculosis will advance our understanding of drug resistance and also set a new paradigm of aminoglycoside acetyltransferase in the antibiotics field.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
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Xu, Zuoyu
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University of Kentucky
Schools of Pharmacy
United States
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Tsodikov, Oleg V; Green, Keith D; Garneau-Tsodikova, Sylvie (2014) A random sequential mechanism of aminoglycoside acetylation by Mycobacterium tuberculosis Eis protein. PLoS One 9:e92370
Fosso, Marina Y; Li, Yijia; Garneau-Tsodikova, Sylvie (2014) New trends in aminoglycosides use. Medchemcomm 5:1075-1091
Houghton, Jacob L; Green, Keith D; Pricer, Rachel E et al. (2013) Unexpected N-acetylation of capreomycin by mycobacterial Eis enzymes. J Antimicrob Chemother 68:800-5
Jennings, Benjamin C; Labby, Kristin J; Green, Keith D et al. (2013) Redesign of substrate specificity and identification of the aminoglycoside binding residues of Eis from Mycobacterium tuberculosis. Biochemistry 52:5125-32
Green, Keith D; Garneau-Tsodikova, Sylvie (2013) Domain dissection and characterization of the aminoglycoside resistance enzyme ANT(3?)-Ii/AAC(6')-IId from Serratia marcescens. Biochimie 95:1319-25
Labby, Kristin J; Garneau-Tsodikova, Sylvie (2013) Strategies to overcome the action of aminoglycoside-modifying enzymes for treating resistant bacterial infections. Future Med Chem 5:1285-309
Berkov-Zrihen, Yifat; Green, Keith D; Labby, Kristin J et al. (2013) Synthesis and evaluation of hetero- and homodimers of ribosome-targeting antibiotics: antimicrobial activity, in vitro inhibition of translation, and drug resistance. J Med Chem 56:5613-25
Houghton, Jacob L; Biswas, Tapan; Chen, Wenjing et al. (2013) Chemical and structural insights into the regioversatility of the aminoglycoside acetyltransferase Eis. Chembiochem 14:2127-35
Green, Keith D; Chen, Wenjing; Garneau-Tsodikova, Sylvie (2012) Identification and characterization of inhibitors of the aminoglycoside resistance acetyltransferase Eis from Mycobacterium tuberculosis. ChemMedChem 7:73-7
Herzog, Ido M; Green, Keith D; Berkov-Zrihen, Yifat et al. (2012) 6''-Thioether tobramycin analogues: towards selective targeting of bacterial membranes. Angew Chem Int Ed Engl 51:5652-6

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