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J Biol Chem. 2015 Feb 20;290(8):4928-40. doi: 10.1074/jbc.M114.601575. Epub 2014 Dec 23.

Mechanistic insights into PTS2-mediated peroxisomal protein import: the co-receptor PEX5L drastically increases the interaction strength between the cargo protein and the receptor PEX7.

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From the Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria,
the Department of Vascular Biology and Thrombosis Research, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria.
the Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, Singapore 138671, and the School of Biological Sciences (SBS), Nanyang Technological University (NTU), 8 Medical Drive, Singapore 117597.
From the Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria.


The destination of peroxisomal matrix proteins is encoded by short peptide sequences, which have been characterized as peroxisomal targeting signals (PTS) residing either at the C terminus (PTS1) or close to the N terminus (PTS2). PTS2-carrying proteins interact with their cognate receptor protein PEX7 that mediates their transport to peroxisomes by a concerted action with a co-receptor protein, which in mammals is the PTS1 receptor PEX5L. Using a modified version of the mammalian two-hybrid assay, we demonstrate that the interaction strength between cargo and PEX7 is drastically increased in the presence of the co-receptor PEX5L. In addition, cargo binding is a prerequisite for the interaction between PEX7 and PEX5L and ectopic overexpression of PTS2-carrying cargo protein drastically increases the formation of PEX7-PEX5L complexes in this assay. Consistently, we find that the peroxisomal transfer of PEX7 depends on cargo binding and that ectopic overexpression of cargo protein stimulates this process. Thus, the sequential formation of a highly stable trimeric complex involving cargo protein, PEX7 and PEX5L stabilizes cargo binding and is a prerequisite for PTS2-mediated peroxisomal import.


Conformational Change; Mammalian Two-hybrid Assay; PEX5; PEX7; PTS2; Peroxisome; Protein Sorting; Protein Targeting; Receptor; Trimeric Complex

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