Biosynthesis of phosphatidylcholine in bacteria

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Phosphatidylcholine (PC) is a major eukaryotic membrane phospholipid, synthesized via methylation or CDP-choline pathways.
• While many prokaryotes lack PC, over 10% of bacteria possess it, challenging previous assumptions.
• The enzymatic methylation of phosphatidylethanolamine was considered the sole bacterial PC biosynthesis route.

Purpose of the Study:

• To investigate novel pathways for phosphatidylcholine (PC) biosynthesis in bacteria.
• To explore the prevalence and mechanisms of PC synthesis in diverse bacterial species.
• To understand the role of host-derived choline in bacterial PC production.

Main Methods:

• Genomic data analysis to estimate PC prevalence in bacteria.
• Biochemical characterization of the PC synthase pathway in Sinorhizobium meliloti.
• Comparative analysis of PC biosynthesis pathways across various bacterial species.

Main Results:

• A novel choline-dependent PC biosynthesis pathway, involving PC synthase, was identified in Sinorhizobium meliloti.
• This pathway directly condenses choline with CDP-diacylglyceride to form PC.
• Several symbiotic and pathogenic bacteria appear to utilize this PC synthase pathway, likely sourcing choline from eukaryotic hosts.
• Some bacteria may employ a CDP-choline pathway, evidenced by choline phosphate and CDP-choline intermediates.

Conclusions:

• The discovery of the PC synthase pathway broadens our understanding of bacterial lipid metabolism.
• Bacterial PC biosynthesis is more diverse than previously thought, with potential host-dependent mechanisms.
• Further research is needed to elucidate the full extent and regulation of bacterial PC synthesis pathways, including the CDP-choline route.