PDBsum entry 5o68

Membrane protein

PDB id: 5o68

Contents

Protein chains

272 a.a.

(+ 2 more) 274 a.a.

254 a.a.

256 a.a.

Ligands

C8E ×5

LDA ×4

References listed in PDB file

Key reference

• Title: A new class of hybrid secretion system is employed in pseudomonas amyloid biogenesis.
• Authors: S.L.Rouse, W.J.Hawthorne, J.L.Berry, D.S.Chorev, S.A.Ionescu, S.Lambert, F.Stylianou, W.Ewert, U.Mackie, R.M.L.Morgan, D.Otzen, F.A.Herbst, P.H.Nielsen, M.Dueholm, H.Bayley, C.V.Robinson, S.Hare, S.Matthews.
• Ref.: Nat Commun, 2017, 8, 263.
• PubMed id: 28811582

Abstract

Gram-negative bacteria possess specialised biogenesis machineries that facilitate the export of amyloid subunits for construction of a biofilm matrix. The secretion of bacterial functional amyloid requires a bespoke outer-membrane protein channel through which unfolded amyloid substrates are translocated. Here, we combine X-ray crystallography, native mass spectrometry, single-channel electrical recording, molecular simulations and circular dichroism measurements to provide high-resolution structural insight into the functional amyloid transporter from Pseudomonas, FapF. FapF forms a trimer of gated β-barrel channels in which opening is regulated by a helical plug connected to an extended coil-coiled platform spanning the bacterial periplasm. Although FapF represents a unique type of secretion system, it shares mechanistic features with a diverse range of peptide translocation systems. Our findings highlight alternative strategies for handling and export of amyloid protein sequences.Gram-negative bacteria assemble biofilms from amyloid fibres, which translocate across the outer membrane as unfolded amyloid precursors through a secretion system. Here, the authors characterise the structural details of the amyloid transporter FapF in Pseudomonas.