Candida albicans is a dimorphic fungus exhibiting either a budding yeast or hyphal phase. A shift from the yeast phase to the hyphal phase can generally be induced by increasing the temperature of incubation from 25°C to 37°C. This shift occurs over a four hour period as approximately 90% of the yeast cells form germ tubes during this time.Interestingly, the specific activity of S-adenosylmethionine synthetase increases during the shift in vegetative cell types and begins to decrease after the 4 hour period. Utilizing the protein synthesis inhibitor tricodermin, we have demonstrated that the increase in specific activity requires de novo protein synthesis.SAM synthetase was characterized (in vitro) by kinetic analysis and response to putative inhibitors. The yeast phase enzyme had an apparent Km of 0.17 mM for methionine, 0.14 mM for ATP and is inhibited by dimethyl-sulfoxide (DMSO), methionine sulfone and methionine sulfoxide. The hyphal phase enzyme has an apparent Km of 0.06 mM for methionine, 0.02 mM for ATP and its activity is enhanced by the three inhibitors. This preliminary data suggests the presence of isozymes in Candida albicans and the possibility of morphology predominant form.The in vivo studies revealed that the addition of methionine inhibited enzyme activity. In addition, 1 mg/ml cycloleucine (in the presence of methionine) induced the activity of this enzyme, indicating that SAM (along with methionine) is a co-effector of enzyme activity and/or synthesis.Ball State UniversityMuncie, IN 47306
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/183204 |
| Date | 03 June 2011 |
| Creators | Lambert, Richard Harlan |
| Contributors | Garcia, Jose R. |
| Source Sets | Ball State University |
| Detected Language | English |
| Format | x, 93 leaves : ill. ; 28 cm. |
| Source | Virtual Press |
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