Novel pathway for phosphatidylcholine biosynthesis in bacteria associated with eukaryotes

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Phosphatidylcholine (PC) is a major eukaryotic membrane phospholipid.
• Bacterial PC synthesis was primarily attributed to the CDP-choline or methylation pathways.
• PC is found in some bacteria, like Rhizobacteria and Spirochetes.

Purpose of the Study:

• To investigate novel pathways for phosphatidylcholine biosynthesis in bacteria.
• To identify the enzymes and mechanisms involved in this new pathway.
• To explore the prevalence and implications of this pathway in bacterial-eukaryotic interactions.

Main Methods:

• Genomic analysis of Sinorhizobium meliloti.
• Enzymatic assays to characterize PC synthase activity.
• Comparative genomics to identify similar genes in other bacterial species.

Main Results:

• A novel choline-dependent pathway for PC biosynthesis was discovered in Sinorhizobium meliloti.
• This pathway involves a unique enzyme, PC synthase, directly condensing choline with CDP-diacylglyceride.
• Homologous genes for PC synthase were identified in pathogenic bacteria like Pseudomonas aeruginosa, Borrelia burgdorferi, and Legionella pneumophila.

Conclusions:

• The novel PC synthase pathway represents a significant addition to known bacterial lipid biosynthesis routes.
• This pathway is likely present in bacteria with symbiotic or pathogenic associations with eukaryotes.
• Eukaryotic hosts may provide the choline necessary for this bacterial PC synthesis pathway, highlighting host-pathogen metabolic interplay.