ß-Helical architecture of cytoskeletal bactofilin filaments revealed by solid-state NMR.
Proc Natl Acad Sci U S A
; 112(2): E127-36, 2015 Jan 13.
Article
em En
| MEDLINE
| ID: mdl-25550503
ABSTRACT
Bactofilins are a widespread class of bacterial filament-forming proteins, which serve as cytoskeletal scaffolds in various cellular pathways. They are characterized by a conserved architecture, featuring a central conserved domain (DUF583) that is flanked by variable terminal regions. Here, we present a detailed investigation of bactofilin filaments from Caulobacter crescentus by high-resolution solid-state NMR spectroscopy. De novo sequential resonance assignments were obtained for residues Ala39 to Phe137, spanning the conserved DUF583 domain. Analysis of the secondary chemical shifts shows that this core region adopts predominantly ß-sheet secondary structure. Mutational studies of conserved hydrophobic residues located in the identified ß-strand segments suggest that bactofilin folding and polymerization is mediated by an extensive and redundant network of hydrophobic interactions, consistent with the high intrinsic stability of bactofilin polymers. Transmission electron microscopy revealed a propensity of bactofilin to form filament bundles as well as sheet-like, 2D crystalline assemblies, which may represent the supramolecular arrangement of bactofilin in the native context. Based on the diffraction pattern of these 2D crystalline assemblies, scanning transmission electron microscopy measurements of the mass per length of BacA filaments, and the distribution of ß-strand segments identified by solid-state NMR, we propose that the DUF583 domain adopts a ß-helical architecture, in which 18 ß-strand segments are arranged in six consecutive windings of a ß-helix.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Citoesqueleto
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Caulobacter crescentus
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article