title: Reassessment of MxiH subunit orientation and fold within native Shigella T3SS needles using surface labelling and solid-state NMR.
abstract: T3SSs are essential virulence determinants of many Gram-negative bacteria, used to inject bacterial effectors of virulence into eukaryotic host cells. Their major extracellular portion, a ∼50 nm hollow, needle-like structure, is essential to host cell sensing and the conduit for effector secretion. It is formed of a small, conserved subunit arranged as a helical polymer. The structure of the subunit has been studied by electron cryomicroscopy within native polymers and by solid-state NMR in recombinant polymers, yielding two incompatible atomic models. To resolve this controversy, we re-examined the native polymer used for electron cryomicroscopy via surface labelling and solid-state NMR. Our data show the orientation and overall fold of the subunit within this polymer is as established by solid-state NMR for recombinant polymers.
authors.affiliation: Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Joeri
authors.initials: J
authors.lastname: Verasdonck
authors.affiliation: School of Cellular & Molecular Medicine, University of Bristol, BS8 1TD Bristol, United Kingdom.
authors.forename: Da-Kang
authors.initials: DK
authors.lastname: Shen
authors.affiliation: School of Cellular & Molecular Medicine, University of Bristol, BS8 1TD Bristol, United Kingdom.
authors.forename: Alexander
authors.initials: A
authors.lastname: Treadgold
authors.affiliation: School of Chemistry, University of Bristol, BS8 1TS Bristol, United Kingdom.
authors.forename: Christopher
authors.initials: C
authors.lastname: Arthur
authors.affiliation: Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France. Electronic address: a.bockmann@ibcp.fr.
authors.forename: Anja
authors.initials: A
authors.lastname: Böckmann
authors.affiliation: Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland. Electronic address: beme@ethz.ch.
authors.forename: Beat H
authors.initials: BH
authors.lastname: Meier
authors.affiliation: Schools of Cellular & Molecular Medicine and Biochemistry, University of Bristol, BS8 1TD Bristol, United Kingdom. Electronic address: ariel.blocker@bristol.ac.uk.
authors.forename: Ariel J
authors.initials: AJ
authors.lastname: Blocker
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D020285:Cryoelectron Microscopy; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012763:Shigella flexneri / Q000472:pathogenicity*; D000069296:Type III Secretion Systems / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C413572:MxiH protein, Shigella; D000069296:Type III Secretion Systems
keywords: Needle; Shigella; Solid-state NMR; Surface labelling; Type III secretion