How did bacterial ancestors reproduce? Lessons from L-form cells and giant lipid vesicles

In possible scenarios on the origin of life, protocells represent the precursors of the first living cells. To study such hypothetical protocells, giant vesicles are being widely used as a simple model. Lipid vesicles can undergo complex morphological changes enabling self-reproduction such as growth, fission, and extra- and intravesicular budding. These properties of vesicular systems may in some way reflect the mechanism of reproduction used by protocells. Moreover, remarkable similarities exist between the morphological changes observed in giant vesicles and bacterial L-form cells, which represent bacteria that have lost their rigid cell wall, but retain the ability to reproduce. L-forms feature a dismantled cellular structure and are unable to carry out classical binary fission. We propose that the striking similarities in morphological transitions of L-forms and giant lipid vesicles may provide insights into primitive reproductive mechanisms and contribute to a better understanding of the origin and evolution of mechanisms of cell reproduction.status: publishe