The cyl Genes Reveal the Biosynthetic Origins of the GBS Hemolytic Lipid, Granadaene
Group B Streptococcus (GBS) is a β-hemolytic, Gram-positive bacterium that often colonizes the female lower genital tract and is associated with fetal injury, preterm birth, spontaneous abortion, and neonatal infections.
GBS virulence is highly effected by the β-hemolysin/cytolysin, which is toxic to host cells. The researchers showed that the ornithine rhamnolipid pigment, Granadaene, produced by the gene products of the cyl operon, breaks down and destroys red blood cells (hemolytic).
The scientists demonstrated that heterologous expression of the GBS cyl operon conferred hemolysis, pigmentation, and cytoxicity to Lactococcus lactis, a model non-hemolytic Gram-positive bacterium. Similarly, pigment purified from L. lactis is hemolytic, cytolytic, and identical in structure to Granadaene extracted from GBS, this shows that the cyl operon is sufficient for Granadaene production in a heterologous host.
The researchers used a systematic survey of phyletic patterns and contextual associations of the cyl genes, to identify homologs of the cyl operon in physiologically diverse Gram-positive bacteria and propose undescribed functions of cyl gene products. Together, these findings bring greater understanding to the biosynthesis and evolutionary foundations of a key GBS virulence factor and suggest that such potentially toxic lipids may be encoded by other bacteria.
Read the paper - The cyl Genes Reveal the Biosynthetic and Evolutionary Origins of the Group B Streptococcus Hemolytic Lipid, Granadaene