Abstract
The heterodimeric Rag GTPases consisting of RagA (or RagB) and RagC (or RagD) are the key regulator activating the target of rapamycin complex 1 (TORC1) in response to the level of amino acids. The heterodimer between GTP-loaded RagA/B and GDP-loaded RagC/D is the most active form that binds Raptor and leads to the activation of TORC1. Here, we present the crystal structure of Gtr1p(GTP)-Gtr2p(GDP), the active yeast Rag GTPase heterodimer. The structure reveals that GTP-to-GDP conversion on Gtr2p results in a large conformational transition of this subunit, including a large scale rearrangement of a long segment whose corresponding region in RagA is involved in binding to Raptor. In addition, the two GTPase domains of the heterodimer are brought to contact with each other, but without causing any conformational change of the Gtr1p subunit. These features explain how the nucleotide-bound statuses of the two GTPases subunits switch the Raptor binding affinity on and off.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Crystallography, X-Ray
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Guanosine Diphosphate / chemistry*
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Guanosine Diphosphate / genetics
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Guanosine Diphosphate / metabolism
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Guanosine Triphosphate / chemistry*
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Guanosine Triphosphate / genetics
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Guanosine Triphosphate / metabolism
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Monomeric GTP-Binding Proteins / chemistry*
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Monomeric GTP-Binding Proteins / genetics
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Monomeric GTP-Binding Proteins / metabolism
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Multienzyme Complexes / chemistry*
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Multienzyme Complexes / genetics
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Multienzyme Complexes / metabolism
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Protein Binding
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Protein Structure, Quaternary
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Saccharomyces cerevisiae / enzymology*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae Proteins / chemistry*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism
Substances
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GTR2 protein, S cerevisiae
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Gtr1 protein, S cerevisiae
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Multienzyme Complexes
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Saccharomyces cerevisiae Proteins
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Guanosine Diphosphate
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Guanosine Triphosphate
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Monomeric GTP-Binding Proteins