Convergent evolution of bacterial ceramide synthesis

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Bacteria synthesize diverse sphingolipids, including ceramides, crucial for modulating host inflammatory responses in the human microbiome.
• The specific biosynthetic pathway for bacterial ceramides was previously unknown due to a lack of homologous enzymes to eukaryotic pathways.

Purpose of the Study:

• To elucidate the complete biosynthetic pathway for bacterial ceramide synthesis.
• To investigate the prevalence and evolutionary origins of this pathway in bacteria.

Main Methods:

• Genomic analysis to identify candidate proteins involved in ceramide synthesis.
• Biochemical assays to confirm enzyme function and pathway order.
• Bioinformatic and phylogenetic analyses to assess pathway distribution and evolutionary history.

Main Results:

• Six proteins constituting the complete bacterial ceramide synthesis pathway were identified.
• Bioinformatic analysis indicated a widespread potential for ceramide synthesis across bacterial species, including a newly discovered Gram-positive producer.
• Biochemical data showed the bacterial pathway proceeds in a distinct sequence compared to eukaryotes.
• Phylogenetic analysis supported independent evolutionary origins for bacterial and eukaryotic ceramide pathways.

Conclusions:

• A complete pathway for bacterial ceramide synthesis has been defined.
• The bacterial ceramide pathway is evolutionarily distinct from its eukaryotic counterpart.
• This finding expands our understanding of microbial lipid metabolism and its implications for host-microbe interactions.