Abstract
While the function of most small signaling domains is confined to binary ligand interactions, the peroxisomal Pex13p SH3 domain has the unique capacity of binding to two different ligands, Pex5p and Pex14p. We have used this domain as a model to decipher its structurally independent ligand binding sites. By the combined use of X-ray crystallography, NMR spectroscopy, and circular dichroism, we show that the two ligands bind in unrelated conformations to patches located at opposite surfaces of this SH3 domain. Mutations in the Pex13p SH3 domain that abolish interactions within the Pex13p-Pex5p interface specifically impair PTS1-dependent protein import into yeast peroxisomes.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Motifs
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Amino Acid Sequence
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Binding Sites
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Carrier Proteins / chemistry
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Circular Dichroism
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Crystallography, X-Ray
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Escherichia coli / metabolism
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Ligands
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Magnetic Resonance Spectroscopy
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Membrane Proteins / chemistry*
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Membrane Transport Proteins
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Microscopy, Fluorescence
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Models, Genetic
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Models, Molecular
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Mutation
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Peptides / chemistry
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Peroxins
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Peroxisome-Targeting Signal 1 Receptor
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Peroxisomes / chemistry*
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Plasmids / metabolism
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Protein Binding
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Protein Conformation
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Protein Structure, Secondary
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Protein Structure, Tertiary
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Receptors, Cytoplasmic and Nuclear / chemistry
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Repressor Proteins*
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins*
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Sequence Homology, Amino Acid
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Time Factors
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X-Rays
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src Homology Domains*
Substances
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Carrier Proteins
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Ligands
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Membrane Proteins
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Membrane Transport Proteins
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PEX13 protein, S cerevisiae
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PEX14 protein, S cerevisiae
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Peptides
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Peroxins
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Peroxisome-Targeting Signal 1 Receptor
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Receptors, Cytoplasmic and Nuclear
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Repressor Proteins
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Saccharomyces cerevisiae Proteins