title: Conservation of targeting but divergence in function and quality control of peroxisomal ABC transporters: an analysis using cross-kingdom expression.
abstract: ABC (ATP-binding cassette) subfamily D transporters are found in all eukaryotic kingdoms and are known to play essential roles in mammals and plants; however, their number, organization and physiological contexts differ. Via cross-kingdom expression experiments, we have explored the conservation of targeting, protein stability and function between mammalian and plant ABCD transporters. When expressed in tobacco epidermal cells, the mammalian ABCD proteins ALDP (adrenoleukodystrophy protein), ALDR (adrenoleukodystrophy-related protein) and PMP70 (70 kDa peroxisomal membrane protein) targeted faithfully to peroxisomes and P70R (PMP70-related protein) targeted to the ER (endoplasmic reticulum), as in the native host. The Arabidopsis thaliana peroxin AtPex19_1 interacted with human peroxisomal ABC transporters both in vivo and in vitro, providing an explanation for the fidelity of targeting. The fate of X-linked adrenoleukodystrophy disease-related mutants differed between fibroblasts and plant cells. In fibroblasts, levels of ALDP in some 'protein-absent' mutants were increased by low-temperature culture, in some cases restoring function. In contrast, all mutant ALDP proteins examined were stable and correctly targeted in plant cells, regardless of their fate in fibroblasts. ALDR complemented the seed germination defect of the Arabidopsis cts-1 mutant which lacks the peroxisomal ABCD transporter CTS (Comatose), but neither ALDR nor ALDP was able to rescue the defect in fatty acid β-oxidation in establishing seedlings. Taken together, our results indicate that the mechanism for trafficking of peroxisomal membrane proteins is shared between plants and mammals, but suggest differences in the sensing and turnover of mutant ABC transporter proteins and differences in substrate specificity and/or function.
authors.affiliation: Biological Chemistry Department, Rothamsted Research, Harpenden, Herts. AL5 2JQ, UK.
authors.forename: Xuebin
authors.initials: X
authors.lastname: Zhang
authors.forename: Carine
authors.initials: C
authors.lastname: De Marcos Lousa
authors.forename: Nellie
authors.initials: N
authors.lastname: Schutte-Lensink
authors.forename: Rob
authors.initials: R
authors.lastname: Ofman
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Wanders
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Baldwin
authors.forename: Alison
authors.initials: A
authors.lastname: Baker
authors.forename: Stephan
authors.initials: S
authors.lastname: Kemp
authors.forename: Frederica L
authors.initials: FL
authors.lastname: Theodoulou
mesh_terms: D000074061:ATP Binding Cassette Transporter, Subfamily D; D000074063:ATP Binding Cassette Transporter, Subfamily D, Member 1; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism / Q000502:physiology*; D000326:Adrenoleukodystrophy / Q000235:genetics / Q000503:physiopathology; D000328:Adult; D000818:Animals; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D020675:Peroxisomes / Q000502:physiology*; D013045:Species Specificity; D014026:Nicotiana / Q000378:metabolism
chemical_list: C115572:ABCD1 protein, human; C431694:ABCD2 protein, human; C063305:ABCD3 protein, human; C489273:ABCD4 protein, human; D000074061:ATP Binding Cassette Transporter, Subfamily D; D000074063:ATP Binding Cassette Transporter, Subfamily D, Member 1; D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; D008565:Membrane Proteins; C514419:PEX19 protein, Arabidopsis