Blood group antigen recognition by a Streptococcus pneumoniae virulence factor

Area of Science:

• Microbiology
• Structural Biology
• Glycobiology

Background:

• Streptococcus pneumoniae utilizes a fucose utilization operon containing a virulence factor.
• This factor belongs to glycoside hydrolase family 98 and features fucose-binding modules.
• These modules share sequence identity with Anguilla anguilla fucolectin.

Purpose of the Study:

• To investigate the binding properties and structural basis of fucose-binding modules from Streptococcus pneumoniae.
• To characterize the molecular interactions with fucosylated oligosaccharides and antigens.
• To determine the in vivo relevance of these binding modules in host tissues.

Main Methods:

• Functional assays to assess binding to fucosylated oligosaccharides.
• High-resolution crystallography to determine the structure of ligand-bound modules.
• Fluorescence microscopy to visualize binding to host tissues.

Main Results:

• The fucose-binding modules exhibit multivalent binding to fucosylated oligosaccharides.
• Crystal structures reveal the molecular basis for binding fucose, ABH blood group, and Lewisy antigens.
• Specific binding to mouse lung tissue was demonstrated via fluorescence microscopy.

Conclusions:

• The identified fucose-binding modules represent a new family (family 47) of carbohydrate-binding modules.
• These modules are crucial for Streptococcus pneumoniae's interaction with host tissues, potentially contributing to virulence.
• Understanding these interactions provides insights into pathogen-host recognition mechanisms.