Potential of chimeric membrane lipid formation by Marine Group II archaea: Implication for the “lipid divide” dogma

 Chualun Zhang, Southern University of Science and Technology, Shenzhen, China
 IDEEV - Salle Rosalind Franklin

Chimeric membrane lipids, which combine archaeal ether lipids and bacterial eukaryotic fatty acid lipids, have been proposed as a line of evidence supporting the origin of eukarya from archaea (Villanueva et al. 2017). But, the existence of naturally stable chimeric membrane lipids has yet to be confirmed.

Marine Group II (MGII) archaea, a successful group inhabiting various depths of the ocean, are believed to potentially possess chimeric membrane lipids based on metagenomic data; the lack of pure MGII cultures, however, has hindered conclusive evidence.

Through five years of research, we have successfully established a stable cultivation system for MGII and addressed challenges in detecting MGII membrane lipids. We have obtained complete circular genomes of ten MGII strains from these enriched cultures, revealing significant transitions in lipid synthesis pathways.

Our ongoing research aims to characterize the chimeric membrane lipid composition of different MGII clades through enrichment cultures and investigate the occurrence patterns and driving factors of membrane lipid transitions during MGII clade evolution. We anticipate that our findings will shed light on the contribution of MGII to the marine ether lipid pool and enhance our understanding of the evolutionary processes of membrane lipid transitions from archaea to eukarya.