P. Rehling et al., THE IMPORT RECEPTOR FOR THE PEROXISOMAL TARGETING SIGNAL-2 (PTS2) IN SACCHAROMYCES-CEREVISIAE IS ENCODED BY THE PAS7 GENE, EMBO journal, 15(12), 1996, pp. 2901-2913
The import of peroxisomal matrix proteins is dependent on one of two t
argeting signals, PTS1 and PTS2, We demonstrate in vivo that not only
the import of thiolase but also that of a chimeric protein consisting
of the thiolase PTS2 (amino acids 1-18) fused to the bacterial protein
beta-lactamase is Pas7p dependent, In addition, using a combination o
f several independent approaches (two-hybrid system, co-immunoprecipit
ation, affinity chromatography and high copy suppression), we show tha
t Pas7p specifically interacts with thiolase in vivo and in vitro, For
this interaction, the N-terminal PTS2 of thiolase is both necessary a
nd sufficient, The specific binding of Pas7p to thiolase does not requ
ire peroxisomes, Pas7p recognizes the PTS2 of thiolase even when this
otherwise N-terminal targeting signal is fused to the C-terminus of ot
her proteins, i,e, the activation domain of Gal4p or GST. These result
s demonstrate that Pas7p is the targeting signal-specific receptor of
thiolase in Saccharomyces cerevisiae and, moreover, are consistent wit
h the view that Pas7p is the general receptor of the PTS2 Our observat
ion that Pas7p also interacts with the human peroxisomal thiolase sugg
ests that in the human peroxisomal disorders characterized by an impor
t defect for PTS2 proteins (classical rhizomelic chondrodysplasia punc
tata), a functional homologue of Pas7p may be impaired.