The Streptococcus pyogenes hyaluronan synthase: sequence comparison and conservation among various group A strains

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• The hyaluronan synthase gene (hasA) from Streptococcus pyogenes was recently cloned.
• Hyaluronan synthase is the first cloned glycosaminoglycan synthase, with limited molecular understanding.
• Enzymes involved in glycosaminoglycan synthesis have not been purified previously.

Purpose of the Study:

• To investigate the molecular relatedness of hyaluronan synthase (HasA) to other known gene products.
• To assess the conservation of the hyaluronan biosynthesis gene operon (hasA/hasB) among Group A streptococcal strains.

Main Methods:

• Sequence database searches were performed to identify proteins with similarities to HasA.
• The polymerase chain reaction (PCR) was utilized to analyze gene conservation across different strains.

Main Results:

• HasA exhibits substantial sequence similarities to proteins such as NodC, DG42, and chitin synthases (Chs).
• These homologous proteins share N-acetylglucosaminyl transferase activity and are membrane-associated.
• The hasA gene and the hyaluronan biosynthesis operon are highly conserved among Group A streptococcal strains, with only five silent mutations found in nine strains spanning over 70 years.

Conclusions:

• Hyaluronan synthase shares molecular similarities with other glycosyltransferases, suggesting a common evolutionary origin or functional domain.
• The high conservation of hyaluronan synthase in Group A streptococci indicates its critical role and stability as a virulence factor.
• In contrast to the conserved hyaluronan synthase, the M protein, another virulence factor, shows considerable variation within the same strains.