Abstract
Prenylated Rab proteins exist in the cytosol as soluble, high-affinity complexes with GDI that need to be disrupted for membrane attachment and targeting of Rab proteins. The Legionella pneumophila protein DrrA displaces GDI from Rab1:GDI complexes, incorporating Rab1 into Legionella-containing vacuoles and activating Rab1 by exchanging GDP for GTP. Here, we present the crystal structure of a complex between the GEF domain of DrrA and Rab1 and a detailed kinetic analysis of this exchange. DrrA efficiently catalyzes nucleotide exchange and mimics the general nucleotide exchange mechanism of mammalian GEFs for Ras-like GTPases. We show that the GEF activity of DrrA is sufficient to displace prenylated Rab1 from the Rab1:GDI complex. Thus, apparent GDI displacement by DrrA is linked directly to nucleotide exchange, suggesting a basic model for GDI displacement and specificity of Rab localization that does not require discrete GDI displacement activity.
2009 Elsevier Inc.
MeSH terms
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Crystallography, X-Ray
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Guanine Nucleotide Dissociation Inhibitors / genetics
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Guanine Nucleotide Dissociation Inhibitors / metabolism*
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Guanine Nucleotide Exchange Factors / genetics
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Guanine Nucleotide Exchange Factors / metabolism
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Guanosine Diphosphate / metabolism*
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Guanosine Triphosphate / metabolism*
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Humans
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Legionella pneumophila / metabolism*
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Models, Molecular
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Molecular Sequence Data
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Multiprotein Complexes / chemistry
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Multiprotein Complexes / metabolism
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Protein Binding
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Protein Conformation
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rab1 GTP-Binding Proteins / chemistry
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rab1 GTP-Binding Proteins / genetics
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rab1 GTP-Binding Proteins / metabolism*
Substances
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Bacterial Proteins
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DNA-Binding Proteins
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DrrA protein, Bacteria
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Guanine Nucleotide Dissociation Inhibitors
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Guanine Nucleotide Exchange Factors
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Multiprotein Complexes
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Guanosine Diphosphate
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Guanosine Triphosphate
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rab1 GTP-Binding Proteins