6N1L

The complement inhibitory domain of B. burgdorferi BBK32.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.72 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.205 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structural determination of the complement inhibitory domain of Borrelia burgdorferi BBK32 provides insight into classical pathway complement evasion by lyme disease spirochetes.

Xie, J.Zhi, H.Garrigues, R.J.Keightley, A.Garcia, B.L.Skare, J.T.

(2019) PLoS Pathog 15: e1007659-e1007659

  • DOI: 10.1371/journal.ppat.1007659
  • Primary Citation of Related Structures:  
    6N1L

  • PubMed Abstract: 
  • The carboxy-terminal domain of the BBK32 protein from Borrelia burgdorferi sensu stricto, termed BBK32-C, binds and inhibits the initiating serine protease of the human classical complement pathway, C1r. In this study we investigated the function of BBK32 orthologues of the Lyme-associated Borrelia burgdorferi sensu lato complex, designated BAD16 from B ...

    The carboxy-terminal domain of the BBK32 protein from Borrelia burgdorferi sensu stricto, termed BBK32-C, binds and inhibits the initiating serine protease of the human classical complement pathway, C1r. In this study we investigated the function of BBK32 orthologues of the Lyme-associated Borrelia burgdorferi sensu lato complex, designated BAD16 from B. afzelii strain PGau and BGD19 from B. garinii strain IP90. Our data show that B. afzelii BAD16-C exhibits BBK32-C-like activities in all assays tested, including high-affinity binding to purified C1r protease and C1 complex, and potent inhibition of the classical complement pathway. Recombinant B. garinii BGD19-C also bound C1 and C1r with high-affinity yet exhibited significantly reduced in vitro complement inhibitory activities relative to BBK32-C or BAD16-C. Interestingly, natively produced BGD19 weakly recognized C1r relative to BBK32 and BAD16 and, unlike these proteins, BGD19 did not confer significant protection from serum killing. Site-directed mutagenesis was performed to convert BBK32-C to resemble BGD19-C at three residue positions that are identical between BBK32 and BAD16 but different in BGD19. The resulting chimeric protein was designated BXK32-C and this BBK32-C variant mimicked the properties observed for BGD19-C. To query the disparate complement inhibitory activities of BBK32 orthologues, the crystal structure of BBK32-C was solved to 1.7Å limiting resolution. BBK32-C adopts an anti-parallel four-helix bundle fold with a fifth alpha-helix protruding from the helical core. The structure revealed that the three residues targeted in the BXK32-C chimera are surface-exposed, further supporting their potential relevance in C1r binding and inhibition. Additional binding assays showed that BBK32-C only recognized C1r fragments containing the serine protease domain. The structure-function studies reported here improve our understanding of how BBK32 recognizes and inhibits C1r and provide new insight into complement evasion mechanisms of Lyme-associated spirochetes of the B. burgdorferi sensu lato complex.


    Organizational Affiliation

    Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Sciences Center, Bryan, Texas, United States of America.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Fibronectin-binding protein BBK32A148Borreliella burgdorferi B31Mutation(s): 0 
Gene Names: bbk32BB_K32
UniProt
Find proteins for O50835 (Borrelia burgdorferi (strain ATCC 35210 / B31 / CIP 102532 / DSM 4680))
Explore O50835 
Go to UniProtKB:  O50835
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

Unit Cell:
Length ( Å )Angle ( ˚ )
a = 66.53α = 90
b = 66.53β = 90
c = 79.508γ = 120
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling
PHENIXphasing

Structure Validation

View Full Validation Report




Entry History & Funding Information

Deposition Data

  • Deposited Date: 2018-11-09 
  • Released Date: 2019-03-27 
  • Deposition Author(s): Garcia, B.L.

Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)United StatesAI133367

Revision History  (Full details and data files)

  • Version 1.0: 2019-03-27
    Type: Initial release
  • Version 1.1: 2019-04-03
    Changes: Data collection, Database references
  • Version 1.2: 2019-12-18
    Changes: Author supporting evidence