NEWLY IDENTIFIED CHINESE-HAMSTER OVARY CELL MUTANTS DEFECTIVE IN PEROXISOME BIOGENESIS REPRESENT 2 NOVEL COMPLEMENTATION GROUPS IN MAMMALS

We isolated peroxisome biogenesis mutants from Chinese hamster ovary ( CHO) cells, using the 9-(1'-pyrene)nonanol/ultraviolet (P9OH/UV) metho d and wild-tt pe CHO-K1 cells that had been stably transfected with cD NA encoding Pex2p (formerly peroxisome assembly factor-ii PAF-1). Thre e mutant cell clones, ZP110, ZP111, and ZP114, showed cytosolic locali zation of catalase, thereby indicating a defect in peroxisome biogenes is, whereas ZP112 and ZP113 contained fewer but larger catalase-positi ve particles, Mutant ZP115 displayed an aberrant, tubular structure im munoreactive to anti-catalase antibody; Mutants lacking morphologicall y recognizable peroxisomes also showed the typical peroxisome assembly -defective phenotype such as severe loss of catalase latency and resis tance to 12-(1'-pyrene)dodecanoic acid (P12)/UV treatment, ZP110 and Z P111, and ZP114 were found to belong to two novel complementation grou ps, respectively; bu complementation group analysis with cDNA transfec tion and cell fusion, Cell fusion with fibroblasts from patients with peroxisome biogenesis disorders such as Zellweger syndrome revealed th at ZP110 and ZP114 could not be classified to any of human complementa tion groups, Thus, ZP110/ZP111 and ZP114 are the first, two peroxisome -deficient cell mutants of newly identified complementation groups dis tinct from the ten mammalian groups previously characterized.