ABSTRACT
A gene encoding a transport protein from the pathogenic yeast, Candida albicans, has been isolated during a complementation experiment utilizing an ornithine decarboxylase-negative (spe1 Delta) strain of Saccharomyces cerevisiae. This gene restores gamma-aminobutyric acid (GABA) transport to a GABA transport-negative mutant of S. cerevisiae and encodes a protein which putatively allows transport of one or more of the polyamines. We have assigned the name GPT1 (GABA/polyamine transporter) to this gene.
Subject(s)
Candida albicans/genetics , Carrier Proteins/genetics , Fungal Proteins , Genes, Fungal , Membrane Transport Proteins , Organic Anion Transporters , Amino Acid Sequence , Base Sequence , Candida albicans/enzymology , Candida albicans/growth & development , Carrier Proteins/metabolism , GABA Plasma Membrane Transport Proteins , Gene Library , Genetic Complementation Test , Membrane Proteins/genetics , Membrane Proteins/metabolism , Molecular Sequence Data , Ornithine Decarboxylase/genetics , Ornithine Decarboxylase/metabolism , Polyamines/metabolism , Saccharomyces cerevisiae Proteins , Sequence Analysis, DNA , Sequence Homology, Amino Acid , gamma-Aminobutyric Acid/physiologyABSTRACT
The morphological plasticity of Candida albicans is an important determinant of pathogenicity, and nonfilamentous mutants are avirulent. HWP1, a hypha-specific gene, was identified in a genetic screen for developmentally regulated genes and encodes a cell surface protein of unknown function. Heterozygous and homozygous deletions of HWP1 resulted in a medium-conditional defect in hyphal development. HWP1 expression was blocked in a Deltaefg1 mutant, reduced in an Deltarbf1 mutant, and derepressed in a Deltatup1 mutant. Therefore, HWP1 functions downstream of the developmental regulators EFG1, TUP1, and RBF1. Mutation of CPH1 had no effect on HWP1 expression, suggesting that the positive regulators of hyphal development, CPH1 and EFG1, are components of separate pathways with different target genes. The expression of a second developmentally regulated gene, ECE1, was similarly regulated by EFG1. Since ECE1 is not required for hyphal development, the regulatory role of EFG1 apparently extends beyond the control of cell shape determinants. However, expression of ECE1 was not influenced by TUP1, suggesting that there may be some specificity in the regulation of morphogenic elements during hyphal development.
Subject(s)
Candida albicans/growth & development , DNA-Binding Proteins/metabolism , Fungal Proteins/metabolism , Membrane Glycoproteins/physiology , Nuclear Proteins , Repressor Proteins , Saccharomyces cerevisiae Proteins , Transcription Factors/metabolism , Amino Acid Sequence , Base Sequence , Candida albicans/genetics , Candida albicans/ultrastructure , DNA, Fungal , DNA-Binding Proteins/genetics , Fungal Proteins/genetics , Gene Expression Regulation, Fungal , Membrane Glycoproteins/genetics , Membrane Glycoproteins/metabolism , Molecular Sequence Data , Mutagenesis , Phenotype , Transcription Factors/geneticsABSTRACT
The gene encoding ornithine decarboxylase, SPE1, from the pathogenic yeast Candida albicans has been isolated by complementation of an ornithine decarboxylase-negative (spe1 delta) strain of Saccharomyces cerevisiae. Four transformants, three of which contain plasmids with the SPE1 gene, were isolated by selection on polyamine-free medium. The C. albicans ornithine decarboxylase (ODC) showed high homology with other eukaryotic ODCs at both the amino acid and nucleic acid levels.
