Abstract
Enzymes with a protein kinase fold transfer phosphate from adenosine 5'-triphosphate (ATP) to substrates in a process known as phosphorylation. Here, we show that the Legionella meta-effector SidJ adopts a protein kinase fold, yet unexpectedly catalyzes protein polyglutamylation. SidJ is activated by host-cell calmodulin to polyglutamylate the SidE family of ubiquitin (Ub) ligases. Crystal structures of the SidJ-calmodulin complex reveal a protein kinase fold that catalyzes ATP-dependent isopeptide bond formation between the amino group of free glutamate and the γ-carboxyl group of an active-site glutamate in SidE. We show that SidJ polyglutamylation of SidE, and the consequent inactivation of Ub ligase activity, is required for successful Legionella replication in a viable eukaryotic host cell.
Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
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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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Biocatalysis
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Calmodulin / chemistry
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Calmodulin / metabolism
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Catalytic Domain
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Crystallography, X-Ray
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HEK293 Cells
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Humans
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Legionella pneumophila / enzymology*
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Legionella pneumophila / genetics
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Legionella pneumophila / pathogenicity
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Phosphorylation
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Polyglutamic Acid / chemistry
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Polyglutamic Acid / genetics
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Polyglutamic Acid / metabolism*
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Protein Domains / genetics
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Protein Kinases / chemistry
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Protein Kinases / genetics
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Protein Kinases / metabolism*
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Ubiquitin-Protein Ligases / genetics
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Ubiquitin-Protein Ligases / metabolism*
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Ubiquitination*
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Virulence Factors / chemistry
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Virulence Factors / genetics
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Virulence Factors / metabolism*
Substances
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Bacterial Proteins
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Calmodulin
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SidJ protein, Legionella pneumophila
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Virulence Factors
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Polyglutamic Acid
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Ubiquitin-Protein Ligases
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Protein Kinases