Essential protein P116 extracts cholesterol and other indispensable lipids for Mycoplasmas

Mycoplasma pneumoniae, responsible for approximately 30% of community-acquired human pneumonia, needs to extract lipids from the host environment for survival and proliferation. Here, we report a comprehensive structural and functional analysis of the previously uncharacterized protein P116 (MPN_213). Single-particle cryo-electron microscopy of P116 reveals a homodimer presenting a previously unseen fold, forming a huge hydrophobic cavity, which is fully accessible to solvent. Lipidomics analysis shows that P116 specifically extracts lipids such as phosphatidylcholine, sphingomyelin and cholesterol. Structures of different conformational states reveal the mechanism by which lipids are extracted. This finding immediately suggests a way to control Mycoplasma infection by interfering with lipid uptake.We thank L. Company and I. Fernández-Vidal for their support during MALS and mass spectroscopy measurements, A. Iborra (Servei de Cultius Cellulars, Anticossos Citometria, UAB) for his assistance with immunizing mice, D. Santos for his assistance in the radioactivity experiment and R. Pérez-Luque and D. Aparicio for their constant support and discussions. J. P. was funded by grants BIO2017-84166-R and PID2021-125632OB-C22 from the ministerio de Ciencia, Innovación y Universidades (MICINN, Spain). I. F. was funded by MICINN-Spain grant PID2021-125632OB-C21. A. S. F. was supported by the Deutsche Forschungsgemeinschaft (FR 1653/14-1 for MS and, FR 1653/6-3 for LS) and the Research Training Group iMOL (GRK 2566/1 for SM)

Structure and mechanism of the Nap adhesion complex from the human pathogen Mycoplasma genitalium

Mycoplasma genitalium is a human pathogen adhering to host target epithelial cells and causing urethritis, cervicitis and pelvic inflammatory disease. Essential for infectivity is a transmembrane adhesion complex called Nap comprising proteins P110 and P140. Here we report the crystal structure of P140 both alone and in complex with the N-terminal domain of P110. By cryo-electron microscopy (cryo-EM) and tomography (cryo-ET) we find closed and open Nap conformations, determined at 9.8 and 15 Å, respectively. Both crystal structures and the cryo-EM structure are found in a closed conformation, where the sialic acid binding site in P110 is occluded. By contrast, the cryo-ET structure shows an open conformation, where the binding site is accessible. Structural information, in combination with functional studies, suggests a mechanism for attachment and release of M. genitalium to and from the host cell receptor, in which Nap conformations alternate to sustain motility and guarantee infectivity.This work was supported by grants BFU2018-101265-B-100 and BIO2017-84166-R from MINECO (Spain). A.S.F. acknowledges the Deutsche Forschungsgemeinschaft Grant FR1653/6-1 and SFB902, as well as the Loewe Dynamem funding for the project. D.A. acknowledges María de Maeztu Unit of Excellence grant MDM-2014-0435