J Biol Chem, Vol. 274, Issue 9, 5666-5673, February 26, 1999
Recombinant Human Peroxisomal Targeting Signal Receptor PEX5
STRUCTURAL BASIS FOR INTERACTION OF PEX5 WITH PEX14
Wolfgang
Schliebs,
Jürgen
Saidowsky,
Bogos
Agianian
,
Gabriele
Dodt,
Friedrich W.
Herberg, and
Wolf-H.
Kunau
From the Institut für Physiologische Chemie,
Ruhr-Universität Bochum, D-44780 Bochum, Germany and
the
European Molecular Biological Laboratory (EMBL)
Heidelberg, Meyerhofstr. 1, D-69012 Heidelberg, Germany
Import of matrix proteins into peroxisomes
requires two targeting signal-specific import receptors, Pex5p and
Pex7p, and their binding partners at the peroxisomal membrane, Pex13p
and Pex14p. Several constructs of human PEX5 have been overexpressed
and purified by affinity chromatography in order to determine
functionally important interactions and provide initial structural
information. Sizing chromatography and electron microscopy suggest that
the two isoforms of the human PTS1 receptor, PEX5L and PEX5S, form homotetramers. Surface plasmon resonance analysis indicates that PEX5
binds to the N-terminal fragment of PEX14-(1-78) with a very high
affinity in the low nanomolar range. Stable complexes between recombinant PEX14-(1-78) and both the full-length and truncated versions of PEX5 were formed in vitro. Analysis of these
complexes revealed that PEX5 possesses multiple binding sites for
PEX14, which appear to be distributed throughout its N-terminal half. Coincidentally, this part of the molecule is also responsible for
oligomerization, whereas the C-terminal half with its seven tetratricopeptide repeats has been reported to bind PTS1-proteins. A
pentapeptide motif that is reiterated seven times in PEX5 is proposed
as a determinant for the interaction with PEX14.
Copyright © 1999 by The American Society for Biochemistry and Molecular Biology, Inc.