Unique C-terminal region of Hap3 is required for methanol-regulated gene expression in the methylotrophic yeast Candida boidinii

• Published in: Microbiology (Society for General Microbiology) 2016-05, Vol.162 (5), p.898-907
• Main Authors: Oda, Saori, Yurimoto, Hiroya, Nitta, Nobuhisa, Sakai, Yasuyoshi
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Candida - genetics; Candida - growth & development; Candida - metabolism; Candida boidinii; CCAAT-Binding Factor - genetics; DNA-Binding Proteins - genetics; Gene Expression - genetics; Gene Expression Regulation, Fungal - genetics; Glycerol - metabolism; Methanol - metabolism; Saccharomyces; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.000275

The Hap complex of the methylotrophic yeast Candida boidinii was found to be required for methanol-regulated gene expression. In this study, we performed functional characterization of CbHap3p, one of the Hap complex components in C. boidinii. Sequence alignment of Hap3 proteins revealed the presence of a unique extended C-terminal region, which is not present in Hap3p from Saccharomyces cerevisiae (ScHap3p), but is found in Hap3p proteins of methylotrophic yeasts. Deletion of the C-terminal region of CbHap3p (Δ256-292 or Δ107-237) diminished activation of methanol-regulated genes and abolished the ability to grow on methanol, but did not affect nuclear localization or DNA-binding ability. However, deletion of the N-terminal region of CbHap3p (Δ1-20) led to not only a growth defect on methanol and a decreased level of methanol-regulated gene expression, but also impaired nuclear localization and binding to methanol-regulated gene promoters. We also revealed that CbHap3p could complement the growth defect of the Schap3Δ strain on glycerol, although ScHap3p could not complement the growth defect of a Cbhap3Δ strain on methanol. We conclude that the unique C-terminal region of CbHap3p contributes to maximum activation of methanol-regulated genes, whilst the N-terminal region is required for nuclear localization and binding to DNA.