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Three Streptococcus pneumoniae sialidases: three different products

Guogang Xu1, Milton J Kiefel, Jennifer C Wilson

  • 1Biomedical Sciences Research Complex, University of St. Andrews, KY16 9ST, UK.

Journal of the American Chemical Society
|January 20, 2011
PubMed

Insights

Streptococcus pneumoniae sialidases NanA, NanB, and NanC are key to its survival and potential drug targets. This study details NanC

Area of Science:

  • Microbiology
  • Biochemistry
  • Enzymology

Background:

  • Streptococcus pneumoniae is a significant human pathogen causing severe diseases like pneumonia, septicemia, and meningitis.
  • Pneumococcal sialidases (NanA, NanB, NanC) are crucial virulence factors and potential therapeutic targets.
  • Understanding the specific enzymatic activities of these sialidases is vital for developing novel treatments.

Purpose of the Study:

  • To elucidate the catalytic mechanisms and products of Streptococcus pneumoniae sialidases, NanA, NanB, and NanC.
  • To characterize the initial product of NanC activity and its subsequent hydration.
  • To compare the catalytic mechanisms of the three pneumococcal sialidases.

Main Methods:

  • Nuclear Magnetic Resonance (NMR) spectroscopy to confirm NanA activity and product configuration.
  • Enzymatic assays to determine the products of NanB and NanC.
  • Characterization of the initial product of NanC and its hydration kinetics.

Main Results:

  • NanA acts as a promiscuous sialidase, releasing Neu5Ac with retention of anomeric configuration.
  • NanB functions as an intramolecular trans-sialidase, selectively producing 2,7-anhydro-Neu5Ac from α2,3-sialosides.
  • NanC's initial product is 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en), which can be slowly hydrated to Neu5Ac.

Conclusions:

  • The three pneumococcal sialidases (NanA, NanB, NanC) likely share a common catalytic mechanism until the final product formation.
  • The distinct products and mechanisms suggest specialized roles for each sialidase in S. pneumoniae pathogenesis.
  • Further investigation into these enzymes could lead to targeted antimicrobial strategies against S. pneumoniae.

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