Mechanistic analysis of the Mycoplasma lipid transporter P116 and putative extracellular chaperone MPN444 using cryo-electron microscopy

• Applicant: Professor Dr. Achilleas Frangakis
• Subject Area: Structural Biology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566927218

In this project, we aim to investigate the function of two essential membrane-bound proteins in Mycoplasma: (i) The lipid transporter P116 acquires and delivers lipids into the membrane singlehandedly and without energy consumption. We have already determined the structure of its ectodomain and visualized it in its native environment on the Mycoplasma membrane. Our goal here is to uncover the precise mechanism underlying lipid acquisition and transfer and, if possible, to explore this unique and remarkable property for potential therapeutic applications. (ii) Additionally, we seek to understand the mechanism of extracellular protein folding in Mycoplasma. This complex and challenging process, which is essential for survival and infectivity, has not been characterized in Mycoplasma, and only few putative complexes have been proposed to perform this function in other bacteria. We have made significant progress, including the structural determination of the essential protein MPN444, which we hypothesize to play an essential role in this process. Going forward, we will conduct functional in vitro studies complemented with cryo-EM and in situ cryo-electron tomography. With the combination of these studies, we aim to gain novel insights into the membrane interactome of Mycoplasma. Thus, we anticipate that our findings will contribute critical knowledge about the biology of the model organism Mycoplasma, which despite its minimal genome and being one of the simplest organisms on the planet is far from understood.

• DFG Programme: Research Grants