Identification and characterization of a novel heme-associated cell surface protein made by Streptococcus pyogenes
Related Experiment Video
Updated: Sep 30, 2026
Biochemical and Structural Characterization of the Carbohydrate Transport Substrate-binding-protein SP0092
Published on: October 2, 2017
Benfang Lei1, Laura M Smoot, Heather M Menning
1Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA.
Abstract:
Analysis of the genome sequence of a serotype M1 group A Streptococcus (GAS) strain identified a gene encoding a previously undescribed putative cell surface protein. The gene was cloned from a serotype M1 strain, and the recombinant protein was overexpressed in Escherichia coli and purified to homogeneity. The purified protein was associated with heme in a 1:1 stoichiometry. This streptococcal heme-associated protein, designated Shp, was produced in vitro by GAS, located on the bacterial cell surface, and accessible to specific antibody raised against the purified recombinant protein. Mice inoculated subcutaneously with GAS and humans with invasive infections and pharyngitis caused by GAS seroconverted to Shp, indicating that Shp was produced in vivo. The blood of mice actively immunized with Shp had significantly higher bactericidal activity than the blood of unimmunized mice. The shp gene was cotranscribed with eight contiguous genes, including homologues of an ABC transporter involved in iron uptake in gram-negative bacteria. Our results indicate that Shp is a novel cell surface heme-associated protein.
Insights
Researchers discovered a novel heme-associated protein (Shp) on the surface of Group A Streptococcus (GAS). This protein is produced in vivo and may be a target for developing new Group A Strep vaccines.
Area of Science:
- Microbiology
- Immunology
- Molecular Biology
Background:
- Group A Streptococcus (GAS) is a significant human pathogen causing various infections.
- Understanding GAS virulence factors and host interactions is crucial for developing effective treatments and vaccines.
Purpose of the Study:
- To identify and characterize novel cell surface proteins of GAS.
- To investigate the role of a newly identified protein in GAS pathogenesis and host immune response.
Main Methods:
- Genome sequence analysis of a serotype M1 GAS strain.
- Gene cloning, protein overexpression in Escherichia coli, and purification.
- Characterization of the protein's association with heme.
- In vitro and in vivo production assessment using GAS cultures and infected animal models.
- Immunization studies in mice to evaluate bactericidal activity.
Main Results:
- A novel putative cell surface protein, designated Shp, was identified and characterized.
- Shp was found to be associated with heme in a 1:1 stoichiometry.
- GAS produces Shp in vitro, and it is located on the bacterial cell surface.
- Shp is produced in vivo during GAS infections, as evidenced by seroconversion in infected mice and humans.
- Active immunization with Shp significantly enhanced the bactericidal activity of mouse blood.
- The shp gene is part of an operon potentially involved in iron uptake.
Conclusions:
- Shp is a novel, cell surface-associated heme-binding protein of Group A Streptococcus.
- Shp is expressed during infection and elicits an in vivo immune response.
- Shp represents a potential target for therapeutic and vaccine development against GAS infections.
Related Concept Videos
01:27Streptococcal Pharyngitis
01:20Determinants of Bacterial Pathogenicity and Virulence
01:29Staphylococcal Skin Infections