Abstract
Sec7-related guanine nucleotide exchange factors (GEFs) initiate vesicle budding from the Golgi membrane surface by converting the GTPase ARF to a GTP-bound, membrane-associated form. Here we report the crystal structure of the catalytic Sec7 homology domain of Arno, a human GEF for ARF1, determined at 2.2 angstroms resolution. The Sec7 domain is an elongated, all-helical protein with a distinctive hydrophobic groove that is phylogenetically conserved. Structure-based mutagenesis identifies the groove and an adjacent conserved loop as the ARF-interacting surface. The sites of Sec7 domain interaction on ARF1 have subsequently been mapped, by protein footprinting experiments, to the switch 1 and switch 2 GTPase regions, leading to a model for the interaction between ARF GTPases and Sec7 domain exchange factors.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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ADP-Ribosylation Factor 1
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ADP-Ribosylation Factors
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Amino Acid Sequence
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Binding Sites
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Crystallography, X-Ray
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Fungal Proteins / chemistry*
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GTP Phosphohydrolases / metabolism*
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GTP-Binding Proteins / chemistry*
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GTP-Binding Proteins / genetics
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GTP-Binding Proteins / metabolism*
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GTPase-Activating Proteins*
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Guanine Nucleotide Exchange Factors*
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Guanosine Diphosphate / metabolism
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Humans
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Protein Structure, Tertiary*
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Sequence Analysis
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Sequence Deletion
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Sequence Homology, Amino Acid
Substances
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Fungal Proteins
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GTPase-Activating Proteins
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Guanine Nucleotide Exchange Factors
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Sec7 guanine nucleotide exchange factors
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cytohesin-2
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Guanosine Diphosphate
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GTP Phosphohydrolases
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GTP-Binding Proteins
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ADP-Ribosylation Factor 1
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ADP-Ribosylation Factors