Characterization of the C-Terminal Nuclease Domain of Herpes Simplex Virus pUL15 as a Target of Nucleotidyltransferase Inhibitors

View/ Open
Issue Date
2016-02-09Author
Masaoka, Takashi
Zhao, Haiyan
Hirsch, Danielle R.
D'Erasmo, Michael P.
Meck, Christine
Varnado, Brittany
Gupta, Ankit
Meyers, Marvin J.
Baines, Joel D.
Beutler, John A.
Murelli, Ryan P.
Tang, Liang
Le Grice, Stuart F. J.
Publisher
ACS
Type
Article
Article Version
Scholarly/refereed, author accepted manuscript
Rights
Copyright © 2016 American Chemical Society
Metadata
Show full item recordAbstract
The natural product α-hydroxytropolones manicol and β-thujaplicinol inhibit replication of herpes simplex viruses 1 and 2 (HSV-1 and HSV-2, respectively) at nontoxic concentrations. Because these were originally developed as divalent metal-sequestering inhibitors of the ribonuclease H activity of HIV-1 reverse transcriptase, α-hydroxytropolones likely target related HSV proteins of the nucleotidyltransferase (NTase) superfamily, which share an “RNase H-like” fold. One potential candidate is pUL15, a component of the viral terminase molecular motor complex, whose C-terminal nuclease domain, pUL15C, has recently been crystallized. Crystallography also provided a working model for DNA occupancy of the nuclease active site, suggesting potential protein–nucleic acid contacts over a region of ∼14 bp. In this work, we extend crystallographic analysis by examining pUL15C-mediated hydrolysis of short, closely related DNA duplexes. In addition to defining a minimal substrate length, this strategy facilitated construction of a dual-probe fluorescence assay for rapid kinetic analysis of wild-type and mutant nucleases. On the basis of its proposed role in binding the phosphate backbone, studies with pUL15C variant Lys700Ala showed that this mutation affected neither binding of duplex DNA nor binding of small molecule to the active site but caused a 17-fold reduction in the turnover rate (kcat), possibly by slowing conversion of the enzyme–substrate complex to the enzyme–product complex and/or inhibiting dissociation from the hydrolysis product. Finally, with a view of pUL15-associated nuclease activity as an antiviral target, the dual-probe fluorescence assay, in combination with differential scanning fluorimetry, was used to demonstrate inhibition by several classes of small molecules that target divalent metal at the active site.
Collections
Citation
Masaoka, T., Zhao, H., Hirsch, D. R., D’Erasmo, M. P., Meck, C., Varnado, B., … Le Grice, S. F. J. (2016). Characterization of the C-Terminal Nuclease Domain of Herpes Simplex Virus pUL15 as a Target of Nucleotidyltransferase Inhibitors. Biochemistry, 55(5), 809–819. http://doi.org/10.1021/acs.biochem.5b01254
Items in KU ScholarWorks are protected by copyright, with all rights reserved, unless otherwise indicated.
We want to hear from you! Please share your stories about how Open Access to this item benefits YOU.