Peroxisomal membrane proteins contain common Pex19p-binding sites that are an integral part of their targeting signals.
Targeting of peroxisomal membrane proteins (PMPs) is a multistep process that requires not only recognition of PMPs in the cytosol but also their insertion into the peroxisomal membrane. As a consequence, targeting signals of PMPs (mPTS) are rather complex. A candidate protein for the PMP recognition event is Pex19p, which interacts with most PMPs. However, the respective Pex19p-binding sites are ill-defined and it is currently disputed whether these sites are contained within mPTS. By using synthetic peptide scans and yeast two-hybrid analyses, we determined and characterized Pex19p-binding sites in Pex11p and Pex13p, two PMPs from Saccharomyces cerevisiae. The sites turned out to be composed of a short helical motif with a minimal length of 11 amino acids. With the acquired data, it proved possible to predict and experimentally verify Pex19p-binding sites in several other PMPs by applying a pattern search and a prediction matrix. A peroxisomally targeted Pex13p fragment became mislocalized to the endoplasmic reticulum in the absence of its Pex19p-binding site. By adding the heterologous binding site of Pex11p, peroxisomal targeting of the Pex13p fragment was restored. We conclude that Pex19p-binding sites are well-defined entities that represent an essential part of the mPTS.
Rottensteiner
Hanspeter
H
Institut für Physiologische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany.
Kramer
Achim
A
Lorenzen
Stephan
S
Stein
Katharina
K
Landgraf
Christiane
C
Volkmer-Engert
Rudolf
R
Erdmann
Ralf
R
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020675:Peroxisomes / Q000737:chemistry / Q000378:metabolism*; D021382:Protein Sorting Signals; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D008565:Membrane Proteins; C109779:PEX19 protein, S cerevisiae; D021382:Protein Sorting Signals; D029701:Saccharomyces cerevisiae Proteins