Peroxisomes are formed from complex membrane structures in PEX6-deficient CHO cells upon genetic complementation.
Pex6p belongs to the AAA family of ATPases. Its CHO mutant, ZP92, lacks normal peroxisomes but contains peroxisomal membrane remnants, so called peroxisomal ghosts, which are detected with anti-70-kDa peroxisomal membrane protein (PMP70) antibody. No peroxisomal matrix proteins were detected inside the ghosts, but exogenously expressed green fluorescent protein (GFP) fused to peroxisome targeting signal-1 (PTS-1) accumulated in the areas adjacent to the ghosts. Electron microscopic examination revealed that PMP70-positive ghosts in ZP92 were complex membrane structures, rather than peroxisomes with reduced matrix protein import ability. In a typical case, a set of one central spherical body and two layers of double-membraned loops were observed, with endoplasmic reticulum present alongside the outer loop. In the early stage of complementation by PEX6 cDNA, catalase and acyl-CoA oxidase accumulated in the lumen of the double-membraned loops. Biochemical analysis revealed that almost all the peroxisomal ghosts were converted into peroxisomes upon complementation. Our results indicate that 1) Peroxisomal ghosts are complex membrane structures; and 2) The complex membrane structures become import competent and are converted into peroxisomes upon complementation with PEX6.
Hashiguchi
Noriyo
N
Department of Life Science, Faculty of Science, Himeji Institute of Technology, Kamigori, Hyogo 678-1297, Japan.
Kojidani
Tomoko
T
Imanaka
Tsuneo
T
Haraguchi
Tokuko
T
Hiraoka
Yasushi
Y
Baumgart
Eveline
E
Yokota
Sadaki
S
Tsukamoto
Toshiro
T
Osumi
Takashi
T
D018528:ATP-Binding Cassette Transporters; D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000172:deficiency / Q000235:genetics*; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D005347:Fibroblasts / Q000502:physiology / Q000648:ultrastructure; D005816:Genetic Complementation Test; D006801:Humans; D008565:Membrane Proteins / Q000502:physiology; D020675:Peroxisomes / Q000502:physiology* / Q000648:ultrastructure
C063305:ABCD3 protein, human; D018528:ATP-Binding Cassette Transporters; C489272:Abcd3 protein, rat; D008565:Membrane Proteins; D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities; C490759:PEX6 protein, human; C096998:Pex6 protein, rat