Characterization of Burkholderia collagen-like proteins.

(A) Architecture of Bucl proteins identified in collagen Pfam data base (not to scale). Proteins were categorized into 13 distinct Bucl types based on sequence similarities and domain organization. Predicted domains in each Bucl are shown: SS, signal sequence; CL, collagen-like domain; Talin-1 domain; Bac_export_1, bacterial export protein family 1; OEP, Outer Membrane Efflux Protein; and SBP_bac_3, bacterial extracellular solute-binding protein family 3. (B) Cellular organization of Bucl8 and homology modelling of the OEP domains. Bucl8 protein schematic is shown above homology model of OEP domains generated with MODELLER. Three monomers, each containing two OEP domains, assemble to form a homotrimer. Shown from top to bottom are the cell-surface exposed loops, the β-barrel spanning the outer membrane and the α-barrel spanning the periplasmic space, corresponding to the predicted OEP domains. The two OEP domains from a single monomer are highlighted in orange and purple, and the remaining monomers are colored gray. Following the OEP domains, the CL region is predicted to be partially extracellular with an additional C-terminal non-collagenous domain.