The isolation of a Dol-P-Man synthase from Ustilago maydis that functions in Saccharomyces cerevisiae

Abstract

Genomic DNAs from several fungi were screened for a homologous sequence to Saccharomyces cerevisiae DPM1, an essential gene which encodes dolichyl phosphoryl mannose synthase. The fungi examined included Aspergillus nidulans, Neurospora crassa, Schizophyllum commune and Ustilago maydis. Only U. maydis gave a significant signal after Southern hybridization using DPM1 as a probe. The Ustilago homolog was subsequently cloned and sequenced. The predicted protein of 294 amino acids has 60% identity to the S. cerevisiae protein, but lacks the putative 'dolichol recognition sequence'. RNA of ca. 900 bp is transcribed in both yeast and filamentous cells of Ustilago. In Escherichia coli, the U. maydis sequence expressed a 35 kDa protein exhibiting dolichyl phosphoryl mannose synthase activity. The sequence was also shown to complement a haploid strain of S. cerevisiae containing a deletion of the DPM1 gene. The U. maydis sequence therefore, encodes a dolichyl phosphoryl mannose synthase that can support normal vegetative growth in S. cerevisiae. The GenBank accession number is U54797.