The 5th International Conference of Geobiology

Membrane lipids are essential for all cellular life, though archaeal lipids differ structurally from their bacterial and eukaryotic counterparts. The formation of archaeal-bacterial hybrid membrane could be occurred in early life evolution. To investigate the physiological changes induced by archaeal-bacterial hybrid membrane formation, we reconstructed the biosynthetic pathway of archaeal lipid glycerol dibiphytanyl glycerol tetraethers (GDGTs) in bacteria Escherichia coli, generating hybrid membrane cells. Remarkably, production of complex archaeal tetraether lipids GDGTs triggered a severe SOS response and cell division defects, resulting in filamentous cells exceeding 200 μm, while simpler archaeal dieter lipids (such as DGGGOH and archaeol) caused no abnormalities, suggesting structural compatibility between membranes may have been crucial for archaeal-bacterial interactions. Supporting this, genomic analysis shows some Asgard archaea (eukaryotic ancestors), which are closest to eukaryote, predominantly produce simple diethers rather than GDGTs, implying evolutionary selection for fusion-compatible lipids. This hybrid membrane system provides a valuable model for studying early cellular membrane evolution and eukaryogenesis.
 

archaeal-bacterial hybrid membrane,archaeal GDGTs,eukaryogenesis