THE HANSEMULA-POLYMORPHA PER6 MUTANT IS AFFECTED IN 2 ADJACENT GENES WHICH ENCODE DIHYDROXYACETONE KINASE AND A NOVEL PROTEIN, PAK1P, INVOLVED IN PEROXISOME INTEGRITY

The Hansenula polymorpha per6-210 mutant is impaired in respect of gro wth on methanol (Mut(-)) and is characterized by aberrant peroxisome f ormation. The functionally complementing DNA fragment contains two ope n reading frames. The first encodes dihydroxyacetone kinase (DAK), a c ytosolic enzyme essential for formaldehyde assimilation; the second OR F codes for a novel protein (Pak1p). We have demonstrated that per6-21 0 cells lack DAK activity, causing the Mut- phenotype, and have strong ly reduced levels of Pak Ip, resulting in peroxisomal defects. Sequenc e analysis revealed that pe r6-210 contains a mutation in the 3' end o f the DAK coding region, which overlaps with the promoter region of PA K1. Possibly this mutation also negatively affects PAK1 expression.