Head-to-Head Prenyl Synthases in Pathogenic Bacteria.

Area of Science:

• Biochemistry
• Enzymology
• Microbiology

Background:

• Head-to-head isoprenoid synthases are present in various organisms.
• Pathogenic bacteria such as Neisseria meningitidis, Neisseria gonorrhoeae, and Enterococcus hirae possess these enzymes.
• Understanding these enzymes is crucial for potential therapeutic targets.

Purpose of the Study:

• To investigate the function and mechanism of head-to-head isoprenoid synthases in Neisseria spp. and E. hirae.
• To compare the enzymatic activity and structural features with known synthases like Staphylococcus aureus CrtM.
• To elucidate the biochemical basis for differences in product formation.

Main Methods:

• Enzyme purification and characterization from Neisseria spp. and E. hirae.
• Product analysis using biochemical assays.
• X-ray crystallography to solve inhibitor-bound enzyme structures.
• Bioinformatics analysis and site-directed mutagenesis.

Main Results:

• The Enterococcus hirae enzyme produced dehydrosqualene, with its structure resembling Staphylococcus aureus CrtM.
• Homologous proteins from Neisseria spp. produced only presqualene diphosphate (PSPP), identified as HpnDs (PSPP synthases).
• A key difference was the presence of a PSPP-stabilizing arginine in Neisseria HpnDs, reducing dehydrosqualene biosynthesis rates.

Conclusions:

• Neisseria spp. and E. hirae harbor distinct head-to-head prenyl synthases.
• Neisseria HpnDs function as PSPP synthases, differing mechanistically from CrtM.
• These findings highlight enzymatic diversity in bacterial isoprenoid biosynthesis, with potential implications for pathogen virulence.