Involvement of the Carboxyl-Terminal Region of the Yeast Peroxisomal Half ABC Transporter Pxa2p in Its Interaction with Pxa1p and in Transporter Function

doi:10.1371/journal.pone.0104892

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Title:	Involvement of the Carboxyl-Terminal Region of the Yeast Peroxisomal Half ABC Transporter Pxa2p in Its Interaction with Pxa1p and in Transporter Function
Authors:	Chuang, Cheng-Yi Chen, Ling-Yun Fu, Ru-Huei Chen, Shih-Ming Ho, Ming-Hua Huang, Jie-Mau Hsu, Chia-Chi Wang, Chien-Cheng Chen, Meng-Shian Tsai, Rong-Tzong
Contributors:	中山醫學大學
Date:	2014
Issue Date:	2015-07-23T08:49:05Z (UTC)
ISSN:	1932-6203
Abstract:	Background The peroxisome is a single membrane-bound organelle in eukaryotic cells involved in lipid metabolism, including β-oxidation of fatty acids. The human genetic disorder X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene (encoding ALDP, a peroxisomal half ATP-binding cassette [ABC] transporter). This disease is characterized by defective peroxisomal β-oxidation and a large accumulation of very long-chain fatty acids in brain white matter, adrenal cortex, and testis. ALDP forms a homodimer proposed to be the functional transporter, whereas the peroxisomal transporter in yeast is a heterodimer comprising two half ABC transporters, Pxa1p and Pxa2p, both orthologs of human ALDP. While the carboxyl-terminal domain of ALDP is engaged in dimerization, it remains unknown whether the same region is involved in the interaction between Pxa1p and Pxa2p. Methods/Principal Findings Using a yeast two-hybrid assay, we found that the carboxyl-terminal region (CT) of Pxa2p, but not of Pxa1p, is required for their interaction. Further analysis indicated that the central part of the CT (designated CT2) of Pxa2p was indispensable for its interaction with the carboxyl terminally truncated Pxa1_NBD. An interaction between the CT of Pxa2p and Pxa1_NBD was not detected, but could be identified in the presence of Pxa2_NBD-CT1. A single mutation of two conserved residues (aligned with X-ALD-associated mutations at the same positions in ALDP) in the CT2 of the Pxa2_NBD-CT protein impaired its interaction with Pxa1_NBD or Pxa1_NBD-CT, resulting in a mutant protein that exhibited a proteinase K digestion profile different from that of the wild-type protein. Functional analysis of these mutant proteins on oleate plates indicated that they were defective in transporter function. Conclusions/Significance The CT of Pxa2p is involved in its interaction with Pxa1p and in transporter function. This concept may be applied to human ALDP studies, helping to establish the pathological mechanism for CT-related X-ALD disease.
URI:	https://ir.csmu.edu.tw:8080/ir/handle/310902500/11585 http://dx.doi.org/10.1371/journal.pone.0104892
Relation:	PLoS ONE 9(8): e104892.
Appears in Collections:	[醫學系] 期刊論文

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