Komagataella phaffii Encodes Two Functional Pho4 Transcription Factors

Area of Science:

• Microbiology
• Molecular Biology
• Yeast Genetics

Background:

• The transcription factor Pho4 regulates phosphate metabolism in fungi.
• Pho4 is also implicated in stress tolerance and pathogenicity.
• Komagataella phaffii was suspected to possess two Pho4 genes, PHO4(A) and PHO4(B), requiring functional characterization.

Purpose of the Study:

• To functionally characterize the two putative Pho4 genes in Komagataella phaffii.
• To investigate the roles of PHO4(A) and PHO4(B) in adaptation to phosphate starvation and alkaline pH.
• To compare the functions of PHO4(A) and PHO4(B) and their contribution to stress response.

Main Methods:

• Phenotypic analysis of single and double pho4 mutants.
• Transcriptomic analysis to assess gene expression changes.
• GFP reporter assays to track gene induction.
• Complementation studies in Saccharomyces cerevisiae.

Main Results:

• Pho4(B) is the primary regulator of the phosphate starvation response in K. phaffii.
• The double mutant pho4(A) pho4(B) is sensitive to phosphate starvation and alkaline pH.
• Pho4(A) contributes to PHO89 induction under high pH stress.
• Both PHO4(A) and PHO4(B) functionally complement a pho4 mutation in S. cerevisiae.

Conclusions:

• K. phaffii possesses two functional Pho4 transcription factors, PHO4(A) and PHO4(B).
• These factors have partially overlapping functions and distinct roles in stress adaptation.
• Together, PHO4(A) and PHO4(B) are essential for K. phaffii's adaptation to multiple environmental stresses.