Crystal structure of accessory secretion protein 1

Experimental Data Snapshot

  • Resolution: 2.77 Å
  • R-Value Free: 0.282 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.212 

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This is version 1.6 of the entry. See complete history


Unraveling the sequence of cytosolic reactions in the export of GspB adhesin fromStreptococcus gordonii.

Chen, Y.Bensing, B.A.Seepersaud, R.Mi, W.Liao, M.Jeffrey, P.D.Shajahan, A.Sonon, R.N.Azadi, P.Sullam, P.M.Rapoport, T.A.

(2018) J Biol Chem 293: 5360-5373

  • DOI: https://doi.org/10.1074/jbc.RA117.000963
  • Primary Citation of Related Structures:  
    5VAE, 5VAF

  • PubMed Abstract: 

    Many pathogenic bacteria, including Streptococcus gordonii , possess a pathway for the cellular export of a single serine-rich-repeat protein that mediates the adhesion of bacteria to host cells and the extracellular matrix. This adhesin protein is O -glycosylated by several cytosolic glycosyltransferases and requires three accessory Sec proteins (Asp1-3) for export, but how the adhesin protein is processed for export is not well understood. Here, we report that the S. gordonii adhesin GspB is sequentially O -glycosylated by three enzymes (GtfA/B, Nss, and Gly) that attach N -acetylglucosamine and glucose to Ser/Thr residues. We also found that modified GspB is transferred from the last glycosyltransferase to the Asp1/2/3 complex. Crystal structures revealed that both Asp1 and Asp3 are related to carbohydrate-binding proteins, suggesting that they interact with carbohydrates and bind glycosylated adhesin, a notion that was supported by further analyses. We further observed that Asp1 also has an affinity for phospholipids, which is attenuated by Asp2. In summary, our findings support a model in which the GspB adhesin is sequentially glycosylated by GtfA/B, Nss, and Gly and then transferred to the Asp1/2/3 complex in which Asp1 mediates the interaction of the Asp1/2/3 complex with the lipid bilayer for targeting of matured GspB to the export machinery.

  • Organizational Affiliation

    From the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Accessory Sec system protein Asp1
A, B, C, D
533Streptococcus gordoniiMutation(s): 0 
Gene Names: asp1
Find proteins for Q9AET9 (Streptococcus gordonii)
Explore Q9AET9 
Go to UniProtKB:  Q9AET9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9AET9
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.77 Å
  • R-Value Free: 0.282 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.212 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 41.502α = 100.66
b = 99.897β = 90.07
c = 179.069γ = 95.78
Software Package:
Software NamePurpose
Aimlessdata scaling
PDB_EXTRACTdata extraction
Cootmodel building

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Howard Hughes Medical Institute (HHMI)United States--
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesGM052586
Helen Hay Whitney FoundationUnited States--

Revision History  (Full details and data files)

  • Version 1.0: 2018-02-21
    Type: Initial release
  • Version 1.1: 2018-02-28
    Changes: Database references
  • Version 1.2: 2018-03-28
    Changes: Data collection, Database references
  • Version 1.3: 2018-04-18
    Changes: Data collection, Database references
  • Version 1.4: 2019-11-20
    Changes: Author supporting evidence
  • Version 1.5: 2020-01-29
    Changes: Derived calculations
  • Version 1.6: 2023-10-04
    Changes: Data collection, Database references, Refinement description