Magnesium uptake by connecting fluid-phase endocytosis to an intracellular inorganic cation filter.

Cells acquire free metals through plasma membrane transporters. But, in natural settings, sequestering agents often render metals inaccessible to transporters, limiting metal bioavailability. Here we identify a pathway for metal acquisition, allowing cells to cope with this situation.

Activation of a peroxisomal Pichia pastoris D-amino acid oxidase, which uses d-alanine as a preferred substrate, depends on pyruvate carboxylase.

d-Amino acid oxidase (DAO) is an important flavo-enzyme that catalyzes the oxidative deamination of d-amino acids into the corresponding alpha-keto acid, ammonia and H(2)O(2). We identified two amino acid oxidases in the methylotrophic yeast Pichia pastoris: Dao1p, which preferentially uses d-alanine as a substrate, and Dao2p, which uses d-aspartate as a preferred substrate. Dao1p has a molecular mass of 38.

The Hansenula polymorpha peroxisomal targeting signal 1 receptor, Pex5p, functions as a tetramer.

We have studied Hansenula polymorpha Pex5p and Pex20p, peroxins involved in peroxisomal matrix protein import. In vitro binding experiments suggested that H. polymorpha Pex5p and Pex20p physically interact.

The transcarboxylase domain of pyruvate carboxylase is essential for assembly of the peroxisomal flavoenzyme alcohol oxidase.

Pyruvate carboxylase (Pyc1p) has multiple functions in methylotrophic yeast species. Besides its function as an enzyme, Pyc1p is required for assembly of peroxisomal alcohol oxidase (AO). Hence, Pyc1p-deficient cells share aspartate auxotrophy (Asp-) with a defect in growth on methanol as sole carbon source (Mut-).