Sprankel, L. | bioRxiv Science

bioRxiv2023

P116 from Mycoplasma is a self-sufficient lipid uptake and delivery machinery

Lipid acquisition and transport are fundamental processes in all organisms. Here, we investigate the lipid uptake and delivery mechanism of the minimal model organism Mycoplasma pneumoniae. We show that the essential protein P116 can transport lipids between liposomes independently and without ATP consumption. Our structural data and molecular dynamics simulations reveal the mechanism by which the N-terminal region of P116 perturbs the membrane, the lipid transfer route, and the regulation of membrane binding by the cargo mass within P116s large hydrophobic cavity. When adequately filled with cargo, P116 undergoes a rapid conformational change that modulates membrane binding. Taken together, our results show that Mycoplasma developed one integrated lipid uptake and delivery machinery that simplifies the complex multi-protein pathways used by higher developed organisms.

molecular biology↗

bioRxiv2022

The immunodominant protein P116 is a passive transporter of cholesterol and other essential lipids

Many human pathogens need to extract lipids from their environment for survival and proliferation. How this is accomplished on a molecular level is largely unknown1. Here, we report a comprehensive structural and functional analysis of the previously uncharacterized protein P116 (MPN_213) from Mycoplasma pneumoniae, a human pathogen responsible for approximately 30% of community-acquired human pneumonia2. Single-particle cryo-electron microscopy of P116 at 3.3 [A] resolution reveals a homodimer with a core domain presenting a previously unseen fold. This fold creates a large cavity of [~]18,000 [A]3 with a hydrophobic internal surface that is accessible to solvent. Within the cavity ligands with a length of 10-19 [A] and a width of 4 [A] could be observed. These ligands were identified as the essential lipids phosphatidylcholine, sphingomyelin and cholesterol using mass spectrometry. When the cavity is emptied, the protein undergoes an extensive conformational change that can no longer accommodate lipids. When emptied P116 is incubated with high-density lipoproteins (HDLs) a net transfer of cholesterol is demonstrated by a radioactivity experiment and cryo-electron microscopy resolves a complex between P116 and HDL. Taken together, our results reveal the mechanism by which P116 extracts essential lipids from the host environment and possibly then delivers them into the membrane by a wringing movement. This mechanism may be precedential for other cholesterol-auxotrophic bacteria.

microbiology↗