Expression of a Pho85 cyclin-dependent kinase is repressed during the dimorphic transition in Sporothrix schenckii.
Sporothrix schenckii is a pathogenic fungus that undergoes a dimorphic transition from yeast to mycelium in response to environmental conditions such as cell density, temperature, and calcium. We identified a homolog of the Pho85 cyclin-dependent kinase (Cdk) that mediates cellular responses to environmental conditions in other organisms. By Western blot, three proteins containing the PSTAIRE motif, which characterize the cyclin-dependent protein kinases, were identified in S. schenckii. The gene encoding a Pho85 homolog, PhoSs, was identified and sequenced. The phoSs gene consists of 990bp, contains one intron, and encodes a protein of 306 amino acids. The S. schenckii Pho85 homolog shares features with Cdks, including the PSTAIRE motif, an ATP binding domain, and a serine-threonine kinase domain. By quantitative competitive RT-PCR, expression of the phoSs gene was found to decrease 30-fold during the yeast to mycelium transition. The addition of extracellular calcium accelerated the dimorphic transition and restored phoSs expression. These findings suggest PhoSs may participate in the control of the yeast to mycelium transition in S. schenckii.
de Jesús-Berríos
Marisol
M
Department of Microbiology and Medical Zoology, Medical Sciences Campus, University of Puerto Rico, San Juan 00936, USA. dejesus@duke.edu
Rodríguez-del Valle
Nuri
N
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis* / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013175:Sporothrix / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
D018844:Cyclin-Dependent Kinases