Conformational analysis of the Streptococcus pneumoniae hyaluronate lyase and characterization of its hyaluronan-specific carbohydrate-binding module.

J Biol Chem. 2014 Aug 6. pii: jbc.M114.578435. [Epub ahead of print]

Conformational analysis of the Streptococcus pneumoniae hyaluronate lyase and characterization of its hyaluronan-specific carbohydrate-binding module.

Suits MD1, Pluvinage B2, Law A2, Liu Y3, Palma AS3, Chai W3, Feizi T4, Boraston AB5.

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Abstract

For a subset of pathogenic microorganisms, including Streptococcus pneumoniae, the recognition and degradation of host hyaluronan contributes to bacterial spreading through the extracellular matrix and enhancing access to host-cell surfaces. The hyaluronate lyase, Hyl, presented on the surface of S. pneumoniae performs this role. Using glycan microarray screening, affinity electrophoresis, and isothermal titration calorimetry we show that the N-terminal module of Hyl is a hyaluronan-specific carbohydrate-binding module (CBM) and the founding member of CBM family 70. The 1.2 Å resolution X-ray crystal structure of CBM70 revealed it to have a β-sandwich fold similar to other CBMs. The electrostatic properties of the binding site, which was identified by site-directed mutagenesis, are distinct from other CBMs and complementary to its acidic ligand, hyaluronan. Dynamic light scattering and solution small-angle X-ray scattering (SAXS) revealed the full-length Hyl protein to exist as a monomer-dimer mixture in solution. Through a detailed analysis of the SAXS data we report the pseudo-atomic solution structures of the monomer and dimer forms of the full-length multimodular Hyl.

Copyright © 2014, The American Society for Biochemistry and Molecular Biology.

KEYWORDS:

Streptococcus; carbohydrate; carbohydrate processing; carbohydrate-binding protein; crystallography; glycobiology; hyaluronan; hyaluronate lyase; small-angle X-ray scattering (SAXS)

PMID: 25100731 [PubMed - as supplied by publisher] Free full text