Chitin is a critical component of the fungal cell wall and a potential target for antifungal drugs. The human pathogenic fungus Candida albicans has four chitin synthase genes. CaCHS8, the fourth CHS gene, has only recently been recognized characterized. This gene encodes a Class I CS, whose activity may be partially redundant with another Class I enzyme – Chs2. CaChs8 contributes actively to in vitro CSI activity, but is dispensable for growth, viability and pathogenesis of C. albicans. A double chs2/chs8 mutant in the two Class I enzymes had less than 5% of the wild type CS activity, but had a normal morphology and only a marginal decrease in chitin content. Regulation of CHS2 and CHS3 was studied, by placing the ORFs of these genes under the promoters of the reciprocal gene. This showed that in C. albicans CHS2 promoter was stronger than CHS3 and was capable of driving elevated levels of CHS3 mRNA, CS activity and resulted in an increase in chitin content of the transformants. However, the results suggest that posttranscriptional control of CSIII activity is less strong in C. albicans than in S. cerevisiae. CHS promoter probes were constructed using a LacZ reporter system to allow assessment to be made of the transcriptional responses of all four CHS genes in relation to various challenges to cell integrity. Results will be presented to examine which CHS gene(s) respond to cell wall damage and environmental perturbation.
Full conference title:
The 15 th Congress of the International Society for Human and Animal Mycology
- ISHAM 15th (2003)