Newly identified Chinese hamster ovary cell mutants are defective in biogenesis of peroxisomal membrane vesicles (Peroxisomal ghosts), representing a novel complementation group in mammals.
We isolated peroxisome biogenesis-defective mutants from Chinese hamster ovary cells by the 9-(1'-pyrene)nonanol/ultraviolet (P9OH/UV) method. Seven cell mutants, ZP116, ZP119, ZP160, ZP161, ZP162, ZP164, and ZP165, of 11 P9OH/UV-resistant cell clones showed cytosolic localization of catalase, a peroxisomal matrix enzyme, apparently indicating a defect of peroxisome biogenesis. By transfection of PEX cDNAs and cell fusion analysis, mutants ZP119 and ZP165 were found to belong to a novel complementation group (CG), distinct from earlier mutants. CG analysis by cell fusion with fibroblasts from patients with peroxisome biogenesis disorders such as Zellweger syndrome indicated that ZP119 and ZP165 were in the same CG as the most recently identified human CG-J. The peroxisomal matrix proteins examined, including PTS1 proteins as well as a PTS2 protein, 3-ketoacyl-CoA thiolase, were also found in the cytosol in ZP119 and ZP165. Furthermore, these mutants showed typical peroxisome assembly-defective phenotype such as severe loss of resistance to 12-(1'-pyrene)dodecanoic acid/UV treatment. Most strikingly, peroxisomal reminiscent vesicular structures, so-called peroxisomal ghosts noted in all CGs of earlier Chinese hamster ovary cell mutants as well as in eight CGs of patients' fibroblasts, were not discernible in ZP119 and ZP165, despite normal synthesis of peroxisomal membrane proteins. Accordingly, ZP119 and ZP165 are the first cell mutants defective in import of both soluble and membrane proteins, representing the 14th peroxisome-deficient CG in mammals, including humans.
Kinoshita
N
N
Department of Biology, Kyushu University Faculty of Science, Fukuoka 812-8581, Japan.
Ghaedi
K
K
Shimozawa
N
N
Wanders
R J
RJ
Matsuzono
Y
Y
Imanaka
T
T
Okumoto
K
K
Suzuki
Y
Y
Kondo
N
N
Fujiki
Y
Y
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D002374:Catalase / Q000378:metabolism; D002459:Cell Fusion; D002461:Cell Line, Transformed; D006224:Cricetinae; D005347:Fibroblasts / Q000502:physiology; D005816:Genetic Complementation Test; D006801:Humans; D008322:Mammals; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D008830:Microbodies / Q000235:genetics*; D016296:Mutagenesis; D000074428:Peroxisomal Biogenesis Factor 2; D000074435:Peroxisome-Targeting Signal 1 Receptor; D011721:Pyrenes; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection; D014466:Ultraviolet Rays; D015211:Zellweger Syndrome / Q000235:genetics / Q000503:physiopathology
D008565:Membrane Proteins; D000074435:Peroxisome-Targeting Signal 1 Receptor; D011721:Pyrenes; D018160:Receptors, Cytoplasmic and Nuclear; D000074428:Peroxisomal Biogenesis Factor 2; D002374:Catalase; D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities; C490759:PEX6 protein, human; C096998:Pex6 protein, rat