The Crystal Structure of Escherichia coli Group 4 Capsule Protein GfcC Reveals a Domain Organization Resembling That of Wza
- Michigan
We report the 1.9 {angstrom} 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 {beta}-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 {beta}-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 {beta}-barrel pore in some species and fusion proteins necessary for secreting biofilm-forming exopolysaccharides.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- OTHERUNIVERSITYOTHER U.S. STATES
- OSTI ID:
- 1031372
- Journal Information:
- Biochemistry-US, Vol. 50, Issue (24) ; 06, 2011; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
The TPR domain of PgaA is a multifunctional scaffold that binds PNAG and modulates PgaB-dependent polymer processing
Exopolysaccharide-associated protein sorting in environmental organisms: the PEP-CTERM/EpsH system. Application of a novel phylogenetic profiling heuristic