Peroxisome-deficient Chinese hamster ovary cells with point mutations in peroxisome assembly factor-1.

Chinese hamster ovary (CHO) mutant cells deficient in peroxisome biogenesis regain peroxisomes after transfection with a cDNA coding for peroxisome assembly factor (PAF)-1 from rat liver. Reconstitution of the transfected mutant cells with wild-type cytoplasm was not required, demonstrating that expression of the PAF-1 gene alone was sufficient for the restoration of peroxisome biogenesis. Plasmalogen biosynthesis in the transfected mutants was also restored to approximately wild-type levels. The nucleotide sequence of the cDNA encoding the open reading frame for PAF-1 from CHO-K1 cells was determined. This allowed us to identify point mutations of PAF-1 in two peroxisomal mutant cell lines. The mutation in ZR-78 cells changed a cysteine to a tyrosine codon in a region located at the carboxyl terminus of the protein, which resembles the zinc finger motif of DNA-binding proteins. A point mutation in the PAF-1 gene of ZR-82 leads to premature termination.