skip to main content

Title: Structural characterization of the virulence factor nuclease A from Streptococcus agalactiae

The group B pathogen Streptococcus agalactiae commonly populates the human gut and urogenital tract, and is a major cause of infection-based mortality in neonatal infants and in elderly or immunocompromised adults. Nuclease A (GBS_NucA), a secreted DNA/RNA nuclease, serves as a virulence factor for S. agalactiae , facilitating bacterial evasion of the human innate immune response. GBS_NucA efficiently degrades the DNA matrix component of neutrophil extracellular traps (NETs), which attempt to kill and clear invading bacteria during the early stages of infection. In order to better understand the mechanisms of DNA substrate binding and catalysis of GBS_NucA, the high-resolution structure of a catalytically inactive mutant (H148G) was solved by X-ray crystallography. Several mutants on the surface of GBS_NucA which might influence DNA substrate binding and catalysis were generated and evaluated using an imidazole chemical rescue technique. While several of these mutants severely inhibited nuclease activity, two mutants (K146R and Q183A) exhibited significantly increased activity. Lastly, these structural and biochemical studies have greatly increased our understanding of the mechanism of action of GBS_NucA in bacterial virulence and may serve as a foundation for the structure-based drug design of antibacterial compounds targeted to S. agalactiae.
Authors:
 [1] ;  [2] ;  [1]
  1. National Inst. of Health, Research Triangle Park, NC (United States)
  2. Inst. National de la Recherche Agronomique (Inra), Jouy-en-Josas (France)
Publication Date:
OSTI Identifier:
1253796
Grant/Contract Number:
W-31-109-Eng-38
Type:
Accepted Manuscript
Journal Name:
Acta Crystallographica. Section D: Biological Crystallography (Online)
Additional Journal Information:
Journal Name: Acta Crystallographica. Section D: Biological Crystallography (Online); Journal Volume: 70; Journal Issue: 11; Journal ID: ISSN 1399-0047
Publisher:
International Union of Crystallography
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Institutes of Health (NIH); Institut National de la Recherche Agronomique (PG)
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES; 60 APPLIED LIFE SCIENCES; nuclease A; virulence factors; Streptococcus agalactiae