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Antimicrobial Agents and Chemotherapy, 12 1995, 2708-2717, Vol 39, No. 12
A Geber, CA Hitchcock, JE Swartz, FS Pullen, KE Marsden, KJ Kwon-Chung and JE Bennett
We have cloned and sequenced the structural genes encoding the delta 5,6
sterol desaturase (ERG3 gene) and the 14 alpha-methyl sterol demethylase
(ERG11 gene) from Candida glabrata L5 (leu2). Single and double mutants of
these genes were created by gene deletion. The phenotypes of these mutants,
including sterol profiles, aerobic viabilities, antifungal
susceptibilities, and generation times, were studied. Strain L5D (erg3
delta::LEU2) accumulated mainly ergosta-7,22- dien-3 beta-ol, was
aerobically viable, and remained susceptible to antifungal agents but had a
slower generation time than its parent strain. L5LUD (LEU2 erg11
delta::URA3) strains required medium supplemented with ergosterol and an
anaerobic environment for growth. A spontaneous aerobically viable mutant,
L5LUD40R (LEU erg11 delta::URA3), obtained from L5LUD (LEU2 erg11
delta::URA3), was found to accumulate lanosterol and obtusifoliol, was
resistant to azole antifungal agents, demonstrated some increase in
resistance to amphotericin B, and exhibited a 1.86-fold increase in
generation time in comparison with L5 (leu2). The double-deletion mutant
L5DUD61 (erg3 delta::LEU2 erg11 delta::URA3) was aerobically viable,
produced mainly 14 alpha-methyl fecosterol, and had the same antifungal
susceptibility pattern as L5LUD40R (LEU2 erg11 delta::URA3), and its
generation time was threefold greater than that of L5 (leu2). Northern
(RNA) analysis revealed that the single-deletion mutants had a marked
increase in message for the undeleted ERG3 and ERG11 genes. These results
indicate that differences in antifungal susceptibilities and the
restoration of aerobic viability exist between the C. glabrata ergosterol
mutants created in this study and those sterol mutants with similar genetic
lesions previously reported for Saccharomyces cerevisiae.
Copyright © 1995 by the American Society for Microbiology. All rights reserved.
Deletion of the Candida glabrata ERG3 and ERG11 genes: effect on cell viability, cell growth, sterol composition, and antifungal susceptibility
Department of Medicine, George Washington University Medical Center, Washington, D.C. 20037, USA.
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