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Eukaryotic Cell, October 2009, p. 1604-1614, Vol. 8, No. 10
1535-9778/09/$08.00+0     doi:10.1128/EC.00206-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

The Transcription Factor Homolog CTF1 Regulates β-Oxidation in Candida albicans{triangledown}

Melissa A. Ramírez and Michael C. Lorenz*

Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas

Received 14 July 2009/ Accepted 18 August 2009

Carbon starvation is one of the many stresses to which microbial pathogens are subjected while in the host. Pathways necessary for the utilization of alternative carbon sources, such as gluconeogenesis, the glyoxylate cycle, and β-oxidation of fatty acids, have been shown to be required for full virulence in several systems, including the fungal pathogen Candida albicans. We have investigated the regulatory network governing alternative carbon metabolism in this organism through characterization of transcriptional regulators identified based on the model fungi, Saccharomyces cerevisiae and Aspergillus nidulans. C. albicans has homologs of the ScCAT8/AnFacB and ScADR1/AnAmdX transcription factors that regulate induction of genes encoding the proteins of gluconeogenesis, the glyoxylate cycle, and ethanol utilization. Surprisingly, C. albicans mutants lacking CAT8 or ADR1 have no apparent phenotypes and do not regulate genes for key enzymes of these pathways. Fatty acid degradation and peroxisomal biogenesis are controlled by nonhomologous regulators, OAF1/PIP2 in S. cerevisiae and FarA/FarB in A. nidulans; C. albicans is missing OAF1 and PIP2 and, instead, has a single homolog of the Far proteins, CTF1. We have shown that CTF1 is required for growth on lipids and for expression of genes necessary for β-oxidation, such as FOX2. ctf1{Delta}/ctf1{Delta} (ctf1{Delta}/{Delta}) strains do not, however, show the pleiotropic phenotypes observed for fox2{Delta}/{Delta} mutants. The ctf1{Delta}/{Delta} mutant confers a mild attenuation in virulence, like the fox2{Delta}/{Delta} mutant. Thus, phenotypic and genotypic observations highlight important differences in the regulatory network for alternative carbon metabolism in C. albicans compared to the paradigms developed in other model fungi.

* Corresponding author. Mailing address: Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center, 6431 Fannin, Houston, TX 77030. Phone: (713) 500-7422. Fax: (713) 500-5499. E-mail: Michael.Lorenz{at}uth.tmc.edu

{triangledown} Published ahead of print on 21 August 2009.

Eukaryotic Cell, October 2009, p. 1604-1614, Vol. 8, No. 10
1535-9778/09/$08.00+0     doi:10.1128/EC.00206-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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