Staphylococcus aureus and Bacillus subtilis W23 make polyribitol wall teichoic acids using different enzymatic...

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Wall teichoic acids (WTAs) are crucial anionic polymers in Gram-positive bacteria, influencing cell shape, division, and pathogenesis.
• Both *Bacillus subtilis* W23 and *Staphylococcus aureus* synthesize polyribitol-phosphate (RboP) WTAs and possess similar biosynthetic gene sets.
• Understanding WTA biosynthesis is vital due to their roles in bacterial physiology and infection.

Purpose of the Study:

• To investigate and compare the specific enzymatic pathways for RboP-WTA biosynthesis in *B. subtilis* W23 and *S. aureus*.
• To identify the key enzymes responsible for initiating WTA chain synthesis in these distinct bacterial species.
• To elucidate the functional divergence of homologous enzymes in WTA production.

Main Methods:

• Utilized *in vitro* biochemical reconstitution assays to examine enzyme activity.
• Employed genetic manipulation techniques in *B. subtilis* and *S. aureus* to validate pathway components.
• Characterized the products of specific phosphotransferase enzymes involved in WTA synthesis.

Main Results:

• Demonstrated that *S. aureus* requires the glycerol-phosphate primase TarF for RboP-WTA synthesis.
• *B. subtilis* W23 possesses a TarF homolog, but it synthesizes glycerol-phosphate polymers and is not involved in RboP-WTA synthesis.
• Identified TarK as the functional primase in *B. subtilis* W23 for RboP-WTA synthesis, working in conjunction with TarL for chain extension.

Conclusions:

• The pathways for RboP-WTA biosynthesis are distinct between *B. subtilis* W23 and *S. aureus*, despite gene homology.
• Enzymatic functional divergence, exemplified by TarK replacing TarF in *B. subtilis*, highlights the adaptability of WTA biosynthesis.
• This study underscores the significant enzymatic diversity within the phosphotransferase family critical for WTA synthesis in Gram-positive bacteria.