Crystal structure of keratin 4 binding domain of surface adhesin Srr-1 of S.agalactiae

Experimental Data Snapshot

  • Resolution: 1.70 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.222 

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Structure of KRT4 binding domain of Srr-1 from Streptococcus agalactiae reveals a novel beta-sheet complementation.

Sundaresan, R.Samen, U.Ponnuraj, K.

(2015) Int J Biol Macromol 75C: 97-105

  • DOI: https://doi.org/10.1016/j.ijbiomac.2014.12.048
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The serine rich repeat protein-1 (Srr-1) is an adhesive protein of Streptococcus agalactiae. It is the first bacterial protein identified to interact with human keratin 4 (K4 or KRT4). Within Srr-1, the residues 311-641 constitute the non-repeat ligand binding region (Srr-1-BR(311-641)). The C-terminal part of Srr-1-BR(311-641), comprising of residues 485-642 (termed Srr-1-K4BD), have been identified to bind to K4. Here we report the crystal structure of recombinant Srr-1-K4BD(485-642) and its possible mode of interaction with K4 through docking studies. The dimeric structure of Srr-1-K4BD(485-642) reveals a novel two way "slide lock" parallel β-sheet complementation where the C-terminal strand of one monomer is positioned anti-parallel to the N-terminal strand of the adjacent monomer and this arrangement is not seen so far in any of the homologous structures. The dimerization of Srr-1-K4BD(485-642) observed both in the crystal structure and in solution suggests that similar domain association could also be possible in in vivo and we propose this association would likely generate a new binding site for another host molecule. It is likely that the adhesin can recognize multiple ligands using its ligand binding sub-domains through their intra and inter domain association with one another.

  • Organizational Affiliation

    Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India. Electronic address: pkarthe@hotmail.com.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Serine rich repeat protein-1 (Srr-1)
A, B
166Streptococcus agalactiae NEM316Mutation(s): 0 
Gene Names: gbs1529
Find proteins for Q8E473 (Streptococcus agalactiae serotype III (strain NEM316))
Explore Q8E473 
Go to UniProtKB:  Q8E473
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8E473
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.70 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.222 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 39.05α = 90
b = 71.89β = 96.03
c = 47.32γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-02-11
    Type: Initial release
  • Version 1.1: 2023-09-20
    Changes: Data collection, Database references, Refinement description