The crystal structure of Escherichia coli group 4 capsule protein GfcC reveals a domain organization resembling that of Wza.
Biochemistry
; 50(24): 5465-76, 2011 Jun 21.
Article
em En
| MEDLINE
| ID: mdl-21449614
ABSTRACT
We report the 1.9 Å resolution crystal structure of enteropathogenic Escherichia coli GfcC, a periplasmic protein encoded by the gfc operon, which is essential for assembly of group 4 polysaccharide capsule (O-antigen capsule). Presumed gene orthologs of gfcC are present in capsule-encoding regions of at least 29 genera of Gram-negative bacteria. GfcC, a member of the DUF1017 family, is comprised of tandem ß-grasp (ubiquitin-like) domains (D2 and D3) and a carboxyl-terminal amphipathic helix, a domain arrangement reminiscent of that of Wza that forms an exit pore for group 1 capsule export. Unlike the membrane-spanning C-terminal helix from Wza, the GfcC C-terminal helix packs against D3. Previously unobserved in a ß-grasp domain structure is a 48-residue helical hairpin insert in D2 that binds to D3, constraining its position and sequestering the carboxyl-terminal amphipathic helix. A centrally located and invariant Arg115 not only is essential for proper localization but also forms one of two mostly conserved pockets. Finally, we draw analogies between a GfcC protein fused to an outer membrane ß-barrel pore in some species and fusion proteins necessary for secreting biofilm-forming exopolysaccharides.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Proteínas da Membrana Bacteriana Externa
/
Proteínas de Escherichia coli
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Estados Unidos