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Expression of M6 protein gene of Streptococcus pyogenes in Streptococcus gordonii after chromosomal integration and

G Pozzi1, M R Oggioni, R Manganelli

  • 1Dipartimento di Biologia Molecolare, Università di Siena, Italy.

Research in Microbiology
|June 1, 1992
PubMed

Insights

Streptococcus pyogenes M6 protein was successfully expressed on Streptococcus gordonii cell surfaces. This engineered M6+ S. gordonii showed enhanced survival in human blood and reduced phagocytosis.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Immunology

Background:

  • Streptococcus pyogenes is a significant human pathogen.
  • Surface proteins play crucial roles in bacterial virulence and host interactions.
  • Developing strategies to express heterologous proteins in commensal bacteria is valuable for research.

Purpose of the Study:

  • To express the M6 protein of Streptococcus pyogenes on the surface of Streptococcus gordonii.
  • To investigate the functional consequences of M6 protein expression on S. gordonii's interaction with the host immune system.

Main Methods:

  • Chromosomal integration of a promoterless M6 protein gene (emm-6.1) and an erythromycin resistance gene (ermC) into S. gordonii.
  • Transformation of S. gordonii with the integrated DNA fragment.
  • Selection of transformants based on erythromycin resistance and M6 protein expression.
  • Phenotypic stability assessment and confirmation of gene integration.
  • Opsonophagocytosis assays to evaluate bacterial survival and phagocytosis rates.

Main Results:

  • Successful chromosomal integration and expression of the M6 protein on the S. gordonii surface and secretion.
  • Twenty-eight percent of erythromycin-resistant transformants expressed M6 protein.
  • Stable M6-expressing S. gordonii clones were obtained through transcriptional fusions with chromosomal promoters.
  • M6+ S. gordonii exhibited increased survival in human blood and slower phagocytosis compared to the M- parental strain.

Conclusions:

  • The M6 protein gene can be functionally expressed on the surface of Streptococcus gordonii.
  • Surface expression of M6 protein confers resistance to phagocytosis and enhances survival in human blood.
  • This engineered strain provides a valuable model for studying M6 protein function and host-pathogen interactions.

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