Isolation and characterization of EPD1, an essential gene for pseudohyphal growth of a dimorphic yeast, Candida maltosa.
Additional copies of the centromeric DNA (CEN) region induce pseudohyphal growth in a dimorphic yeast, Candida maltosa (T. Nakazawa, T. Motoyama, H. Horiuchi, A. Ohta, and M. Takagi, J. Bacteriol. 179:5030-5036, 1997). To understand the mechanism of this transition, we screened the gene library of C. maltosa for sequences which could suppress this morphological change. As a result, we isolated the 5' end of a new gene, EPD1 (for essential for pseudohyphal development), and then cloned the entire gene. The predicted amino acid sequence of Epdlp was highly homologous to those of Ggp1/Gas1/Cwh52p, a glycosylphosphatidylinositol-anchored protein of Saccharomyces cerevisiae, and Phr1p and Phr2p of Candida albicans. The expression of EPD1 was moderately regulated by environmental pH. A homozygous EPD1 null mutant showed some morphological defects and reduction in growth rate and reduced levels of both alkali-soluble and alkali-insoluble beta-glucans. Moreover, the mutant could not undergo the transition from yeast form to pseudohyphal form induced by additional copies of the CEN sequence at pH 4 or by n-hexadecane at pH 4 or pH 7, suggesting that EPD1 is not essential for yeast form growth but is essential for transition to the pseudohyphal form. Overexpression of the amino-terminal part of Epd1p under the control of the GAL promoter suppressed the pseudohyphal development induced by additional copies of the CEN sequence, whereas overexpression of the full-length EPD1 did not. This result and the initial isolation of the 5' end of EPD1 as a suppressor of the pseudohyphal growth induced by the CEN sequence suggest that the amino-terminal part of Epd1p may have a dominant-negative effect on the functions of Epd1p in the pseudohyphal growth induced by the CEN sequence.
Nakazawa
T
T
Department of Biotechnology, The University of Tokyo, Japan.
Horiuchi
H
H
Ohta
A
A
Takagi
M
M
D000595:Amino Acid Sequence; D002175:Candida / Q000166:cytology / Q000235:genetics* / Q000254:growth & development*; D002503:Centromere / Q000235:genetics; D004271:DNA, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014158:Transcription, Genetic
D004271:DNA, Fungal; C111940:EPD1 protein, Candida maltosa; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins