Research Synopsis

• Chemical biology of DNA metabolism, recombination and repair
• Development of alternate strategies for targeting antibiotic-resistant bacterial pathogens
• Antibacterial drug design and discovery

Profile

Scott Singleton is an associate professor and vice chair of the Division of Medicinal Chemistry and Natural Products in the UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill. Before his appointment to the UNC in 2003, he was an assistant professor in the Departments of Chemistry and Biochemistry and Cell Biology at Rice University from 1996 to 2003.

Singleton holds a BA in chemistry and in biology from Trinity University in San Antonio, Texas, and a PhD in organic chemistry from the California Institute of Technology. Following his doctoral research with Professor Peter B. Dervan at the California Institute of Technology, Singleton was an NSF postdoctoral fellow with Professor Stephen J. Benkovic at Penn State.

Singleton is an award-winning teacher of organic chemistry and medicinal chemistry for undergraduate, graduate, and professional students. In addition, Singleton has served as secretary of the School's faculty and director of graduate studies for the School's graduate programs in pharmaceutical sciences.

Research

The Singleton laboratory is interested in the chemical biology of DNA metabolism — with an emphasis on recombination and repair -- as it relates to antibiotic resistance in bacterial pathogens. Research in the lab currently covers three project areas:

1. The laboratory has developed assays and reagents for the high-throughput screening of chemical libraries for inhibitors of bacterial SOS targets as well as efficient methods for characterization of those inhibitors. Combining prototypic inhibitors with known antibiotics potentiates the killing of Escherichia coli and Staphylococcus aureus.
2. Working with Lars Pedersen (Laboratory of Structural Biology, National Institute of Environmental Health Sciences) and Alfred Pingoud (Justus-Liebig-Universität, Giessen, Germany), the Singleton lab is validating an assay to identify small-molecule inhibitors of EndA, an extracellular endonuclease that is important for the virulence of Streptococcus pneumonia.
3. Working with Drew Lee (UNC Eshelman School of Pharmacy), the Singleton lab is developing small-molecule inhibitors of the bacterial DHFR enzyme, where the inhibitors are designed to bind to the same site with affinities that span several orders of magnitude in order to test hypotheses related to the relationship between ligand-binding and intrinsic protein dynamics.

Overall, these projects seek to discover new small-molecule probes to tease apart important biological activities leading to antibiotic resistance, as well as to establish new druggable targets for the future management of bacterial infections.

Most Recent Publications

1. Evidence for dynamics in proteins as a mechanism for ligand dissociation. Carroll MJ, Mauldin RV, Gromova AV, Singleton SF, Collins EJ, Lee AL. Nat Chem Biol. 2012 Jan 15. doi: 10.1038/nchembio.769. [Epub ahead of print] PMID: 22246400 [PubMed - as supplied by publisher]

2. High-Throughput Screening for RecA Inhibitors Using a Transcreener Adenosine 5'-O-Diphosphate Assay. Peterson EJ, Janzen WP, Kireev D, Singleton SF. Assay Drug Dev Technol. 2011 Dec 22. [Epub ahead of print] PMID: 22192312 [PubMed - as supplied by publisher]

3. Direct detection of structurally resolved dynamics in a multiconformation receptor-ligand complex. Carroll MJ, Gromova AV, Miller KR, Tang H, Wang XS, Tripathy A, Singleton SF, Collins EJ, Lee AL. J Am Chem Soc. 2011 Apr 27;133(16):6422-8. Epub 2011 Apr 6. PMID: 21469679 [PubMed - indexed for MEDLINE]

4. Novel Inhibitors of E. coli RecA ATPase Activity. Sexton JZ, Wigle TJ, He Q, Hughes MA, Smith GR, Singleton SF, Williams AL, Yeh LA. Curr Chem Genomics. 2010 May 26;4:34-42. PMID: 20648224 [PubMed]

5. Inhibitors of RecA activity discovered by high-throughput screening: cell-permeable small molecules attenuate the SOS response in Escherichia coli. Wigle TJ, Sexton JZ, Gromova AV, Hadimani MB, Hughes MA, Smith GR, Yeh LA, Singleton SF. J Biomol Screen. 2009 Oct;14(9):1092-101. Epub 2009 Aug 12. PMID: 19675313 [PubMed - indexed for MEDLINE] Free PMC Article

6. A complementary pair of rapid molecular screening assays for RecA activities. Lee AM, Wigle TJ, Singleton SF. Anal Biochem. 2007 Aug 15;367(2):247-58. Epub 2007 Apr 20.
PMID: 17601483 [PubMed - indexed for MEDLINE]

7. Directed molecular screening for RecA ATPase inhibitors. Wigle TJ, Singleton SF. Bioorg Med Chem Lett. 2007 Jun 15;17(12):3249-53. Epub 2007 Apr 10. PMID: 17499507 [PubMed - indexed for MEDLINE]

8. Inhibition of Escherichia coli RecA by rationally redesigned N-terminal helix. Cline DJ, Holt SL, Singleton SF. Org Biomol Chem. 2007 May 21;5(10):1525-8. Epub 2007 Apr 18.
PMID: 17571180 [PubMed - indexed for MEDLINE]

9. Probing the structure of RecA-DNA filaments. Advantages of a fluorescent guanine analog.
Singleton SF, Roca AI, Lee AM, Xiao J. Tetrahedron. 2007 Apr 23;63(17):3553-3566. PMID: 17955055 [PubMed]

10. Direct evaluation of a kinetic model for RecA-mediated DNA-strand exchange: the importance of nucleic acid dynamics and entropy during homologous genetic recombination.
Xiao J, Lee AM, Singleton SF. Chembiochem. 2006 Aug;7(8):1265-78. PMID: 16847846 [PubMed - indexed for MEDLINE]