Liu LX, Janvier K, Berteaux-Lecellier V, Cartier N, Benarous R, Aubourg P

Mammalian peroxisomal proteins adrenoleukodystrophy protein (ALDP), adrenoleukodystrophy-related protein (ALDRP), and 70-kDa peroxisomal protein (PMP70) belong to the superfamily of ATP-binding cassette (ABC) transporters. Unlike many ABC transporters that are single functional proteins with two related halves, ALDP, ALDRP, and PMP70 have the structure of ABC half-transporters. The dysfunction of ALDP ...

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is responsible for X-linked adrenoleukodystrophy (X-ALD), a neurodegenerative disorder in which saturated very long-chain fatty acids accumulate because of their impaired peroxisomal beta-oxidation. No disease has so far been associated with mutations of adrenoleukodystrophy-related or PMP70 genes. It has been proposed that peroxisomal ABC transporters need to dimerize to exert import functions. Using the yeast two-hybrid system, we show that homo- as well as heterodimerization occur between the carboxyl-terminal halves of ALDP, ALDRP, and PMP70. Two X-ALD disease mutations located in the carboxyl-terminal half of ALDP affect both homo- and heterodimerization of ALDP. Co-immunoprecipitation demonstrated the homodimerization of ALDP, the heterodimerization of ALDP with PMP70 or ALDRP, and the heterodimerization of ALDRP with PMP70. These results provide the first evidence of both homo- and heterodimerization of mammalian ABC half-transporters and suggest that the loss of ALDP dimerization plays a role in X-ALD pathogenesis.

Date: Nov. 12, 1999

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