These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Streptococcal M protein: structural studies of the hypervariable region, free and bound to human C4BP.
    Author: André I, Persson J, Blom AM, Nilsson H, Drakenberg T, Lindahl G, Linse S.
    Journal: Biochemistry; 2006 Apr 11; 45(14):4559-68. PubMed ID: 16584191.
    Abstract:
    Streptococcus pyogenes is a Gram-positive bacterium that causes several diseases, including acute tonsillitis and toxic shock syndrome. The surface-localized M protein, which is the most extensively studied virulence factor of S. pyogenes, has an approximately 50-residue N-terminal hypervariable region (HVR) that plays a key role in the escape of the host immunity. Despite the extensive sequence variability in this region, many HVRs specifically bind human C4b-binding protein (C4BP), a plasma protein that inhibits complement activation. Although the more conserved parts of M protein are known to have dimeric coiled-coil structure, it is unclear whether the HVR also is a coiled coil. Here, we use nuclear magnetic resonance (NMR) to study the conformational properties of HVRs from M4 and M22 proteins in isolation and in complex with the M protein binding portion of C4BP. We conclude that the HVRs of M4 and M22 are folded as coiled coils and that the folded nucleus of the M4 HVR has a length of approximately 27 residues. Moreover, we demonstrate that the C4BP binding surface of M4-N is found within a region of four heptad repeats. Using molecular modeling, we propose a model for the structure of the M4 HVR that is consistent with our experimental information from NMR spectroscopy.
    [Abstract] [Full Text] [Related] [New Search]