The basic keratin 10-binding domain of the virulence-associated pneumococcal serine-rich protein PsrP adopts a novel MSCRAMM fold

Open Biol. 2014 Jan 15;4(1):130090. doi: 10.1098/rsob.130090.


Streptococcus pneumoniae is a major human pathogen, and a leading cause of disease and death worldwide. Pneumococcal invasive disease is triggered by initial asymptomatic colonization of the human upper respiratory tract. The pneumococcal serine-rich repeat protein (PsrP) is a lung-specific virulence factor whose functional binding region (BR) binds to keratin-10 (KRT10) and promotes pneumococcal biofilm formation through self-oligomerization. We present the crystal structure of the KRT10-binding domain of PsrP (BR187-385) determined to 2.0 Å resolution. BR187-385 adopts a novel variant of the DEv-IgG fold, typical for microbial surface components recognizing adhesive matrix molecules adhesins, despite very low sequence identity. An extended β-sheet on one side of the compressed, two-sided barrel presents a basic groove that possibly binds to the acidic helical rod domain of KRT10. Our study also demonstrates the importance of the other side of the barrel, formed by extensive well-ordered loops and stabilized by short β-strands, for interaction with KRT10.

Keywords: MSCRAMM; PsrP; Streptococcus pneumoniae; adhesion; bacterial virulence factor; keratin-10.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adhesins, Bacterial / chemistry
  • Adhesins, Bacterial / metabolism
  • Alanine / genetics
  • Alanine / metabolism
  • Amino Acid Substitution
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Crystallography, X-Ray
  • Humans
  • Keratin-10 / chemistry*
  • Keratin-10 / metabolism
  • Models, Molecular*
  • Protein Binding
  • Protein Folding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Static Electricity
  • Streptococcus pneumoniae / metabolism
  • Virulence Factors / chemistry
  • Virulence Factors / genetics
  • Virulence Factors / metabolism*


  • Adhesins, Bacterial
  • Bacterial Proteins
  • Virulence Factors
  • Keratin-10
  • Alanine

Associated data

  • PDB/3ZGH
  • PDB/3ZGI