Cecilia Carnrot, 1. Department of Molecular Biosciences, The Swedish University of Agricultural Biosciences, Biomedical Center, P.O. Box 575, S-751 23 Uppsala, Sweden
1 Susan R. Vogel, 2. Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA
2 Youngjoo Byun, 3. College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA
3 Liya Wang, 4. Department of Molecular Biosciences, The Swedish University of Agricultural Biosciences, Biomedical Center, P.O. Box 575, S-751 23 Uppsala, Sweden
4 Werner Tjarks, 5. College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA
5 Staffan Eriksson, 6. Department of Molecular Biosciences, The Swedish University of Agricultural Biosciences, Biomedical Center, P.O. Box 575, S-751 23 Uppsala, Sweden
6 Andrew J. Phipps7. Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA and Center for Microbial Interface Biology, The Ohio State University, Columbus, OH 43210, USA
7 Corresponding author
Citation Information. Biological Chemistry. Volume 387, Issue 12, Pages 1575–1581, ISSN (Online) 1437-4315, ISSN (Print) 1431-6730, DOI: 10.1515/BC.2006.196, 01/12/2006
Publication History: Received: //; accepted: //; published online: 28/11/2006
Abstract
Bacillus anthracis, which causes anthrax, has attracted attention because of its potential use as a biological weapon. The risk of multidrug resistance against B. anthracis increases the need for antibiotics with new molecular targets. Nucleoside analogs are well-known antiviral and anticancer prodrugs, and thymidine kinase catalyzes the rate-limiting step in the activation of pyrimidine nucleoside analogs used in chemotherapy. The thymidine kinase gene from B. anthracis Sterne strain (34F2) (Ba-TK) was cloned and expressed in E. coli, and the product was purified and characterized regarding its substrate specificity. Ba-TK phosphorylated pyrimidine nucleosides and all natural nucleoside triphosphates served as phosphate donors. Size exclusion chromatography indicated a dimeric form of Ba-TK, regardless of the presence of ATP. Thymidine was the most efficient substrate with a low Km value (0.6 μM) and a Vmax of 3.3 μmol dTMP mg-1 min-1, but deoxyuridine (Km=4.2 μM, Vmax=4.1 μmol dUMP mg-1 min-1) was also a good substrate. Several pyrimidine analogs were also tested and analogs with 5-position modifications showed higher activities compared to analogs with 3′- and N3-position modifications. Deoxyuridine analogs were the most potent inhibitors of B. anthracis growth in vitro. These results may be used to guide future development of nucleoside analogs against B. anthracis.
Keywords characterization, 5-fluoro-deoxyuridine, growth inhibition, kinetics, thymidine
