This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Maligie, M. A. Articles by Selitrennikoff, C. P. Search for Related Content PubMed PubMed Citation Articles by Maligie, M. A. Articles by Selitrennikoff, C. P.

Cryptococcus neoformans Resistance to Echinocandins: (1,3)ß-Glucan Synthase Activity Is Sensitive to Echinocandins

University of Colorado Health Sciences Center, Department of Cell and Developmental Biology, 12635 E. Montview Blvd., Suite 215, Aurora, Colorado 80010

Received 9 December 2004/ Returned for modification 16 January 2005/ Accepted 2 April 2005

(1,3)ß-D-Glucan synthase (EC 2.4.1.34. UDP-glucose: 1,3-ß-D-glucan 3-ß-glucosyltransferase) uses UDP-glucose as substrate and catalyzes the polymerization of glucose ([1,3]-ß-linkages) to form the major carbohydrate component of the fungal cell wall. We have optimized in vitro assay conditions for (1,3)ß-glucan synthase activity from Cryptococcus neoformans. Cells lysed in 50 mM Tris, pH 7.75, containing 20% glycerol, 2 mM NaF, 1 mM dithiothreitol, 0.1 mM phenylmethylsulfonyl fluoride, 5 mM MgCl₂, 0.1% protease and phosphatase inhibitor cocktails, and 60 µM GTPS produced maximum specific activity in vitro. We tested in vitro C. neoformans (1,3)ß-glucan synthase activity against the (1,3)ß-glucan synthase inhibitors, caspofungin and cilofungin, and have determined that (1,3)ß-glucan synthase activity is very sensitive (apparent K_i of 0.17 ± 0.02 µM and 22 ± 5.7 µM, respectively) to these echinocandins. Taken together with high MICs for C. neoformans (caspofungin MIC, 16 µg/ml; cilofungin MIC, 64 µg/ml), our results indicate that C. neoformans is resistant to caspofungin and cilofungin by a mechanism(s) unrelated to (1,3)ß-glucan synthase resistance.

This article has been cited by other articles:

• Cowen, L. E., Steinbach, W. J. (2008). Stress, Drugs, and Evolution: the Role of Cellular Signaling in Fungal Drug Resistance. Eukaryot Cell 7: 747-764 [Full Text]  
• Rachini, A., Pietrella, D., Lupo, P., Torosantucci, A., Chiani, P., Bromuro, C., Proietti, C., Bistoni, F., Cassone, A., Vecchiarelli, A. (2007). An Anti-{beta}-Glucan Monoclonal Antibody Inhibits Growth and Capsule Formation of Cryptococcus neoformans In Vitro and Exerts Therapeutic, Anticryptococcal Activity In Vivo. Infect. Immun. 75: 5085-5094 [Abstract] [Full Text]  
• Baker, L. G., Specht, C. A., Donlin, M. J., Lodge, J. K. (2007). Chitosan, the Deacetylated Form of Chitin, Is Necessary for Cell Wall Integrity in Cryptococcus neoformans. Eukaryot Cell 6: 855-867 [Abstract] [Full Text]  
• Lesage, G., Bussey, H. (2006). Cell Wall Assembly in Saccharomyces cerevisiae. Microbiol. Mol. Biol. Rev. 70: 317-343 [Abstract] [Full Text]  
• Banks, I. R., Specht, C. A., Donlin, M. J., Gerik, K. J., Levitz, S. M., Lodge, J. K. (2005). A Chitin Synthase and Its Regulator Protein Are Critical for Chitosan Production and Growth of the Fungal Pathogen Cryptococcus neoformans. Eukaryot Cell 4: 1902-1912 [Abstract] [Full Text]