title: Structural and functional insights into Escherichia coli α2-macroglobulin endopeptidase snap-trap inhibition.
abstract: The survival of commensal bacteria requires them to evade host peptidases. Gram-negative bacteria from the human gut microbiome encode a relative of the human endopeptidase inhibitor, α2-macroglobulin (α2M). Escherichia coli α2M (ECAM) is a ∼ 180-kDa multidomain membrane-anchored pan-peptidase inhibitor, which is cleaved by host endopeptidases in an accessible bait region. Structural studies by electron microscopy and crystallography reveal that this cleavage causes major structural rearrangement of more than half the 13-domain structure from a native to a compact induced form. It also exposes a reactive thioester bond, which covalently traps the peptidase. Subsequently, peptidase-laden ECAM is shed from the membrane and may dimerize. Trapped peptidases are still active except against very large substrates, so inhibition potentially prevents damage of large cell envelope components, but not host digestion. Mechanistically, these results document a novel monomeric "snap trap."
authors.affiliation: Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), 08028 Barcelona, Spain;
authors.forename: Irene
authors.initials: I
authors.lastname: Garcia-Ferrer
authors.affiliation: Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), 08028 Barcelona, Spain;
authors.forename: Pedro
authors.initials: P
authors.lastname: Arêde
authors.affiliation: Department of Structure of Macromolecules, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain;
authors.forename: Josué
authors.initials: J
authors.lastname: Gómez-Blanco
authors.affiliation: Department of Structure of Macromolecules, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain; Spanish National Microbiology Centre, Institute of Health Carlos III, 28220 Madrid, Spain;
authors.forename: Daniel
authors.initials: D
authors.lastname: Luque
authors.affiliation: Unité de Virologie Structurale, Département de Virologie and CNRS Unité de Recherche Associée 3015, Institut Pasteur, 75724 Paris Cedex 15, France; Departement de Biologie, Faculté des Sciences d'Orsay, Université Paris-Sud, 91405 Orsay, France.
authors.forename: Stephane
authors.initials: S
authors.lastname: Duquerroy
authors.affiliation: Department of Structure of Macromolecules, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain;
authors.forename: José R
authors.initials: JR
authors.lastname: Castón
authors.affiliation: Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), 08028 Barcelona, Spain; thgcri@ibmb.csic.es xgrcri@ibmb.csic.es.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Goulas
authors.affiliation: Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), 08028 Barcelona, Spain; thgcri@ibmb.csic.es xgrcri@ibmb.csic.es.
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Gomis-Rüth
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D010450:Endopeptidases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000378:metabolism / Q000382:microbiology; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D064307:Microbiota / Q000235:genetics; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism*; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D000511:alpha-Macroglobulins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011480:Protease Inhibitors; D000511:alpha-Macroglobulins; D010450:Endopeptidases; D010447:Peptide Hydrolases
keywords: X-ray crystal structure; conformational rearrangement; cryo-electron microscopy; gut microbiome; protein inhibitor