The mycoplasma surface proteins MIB and MIP promote the dissociation of the antibody-antigen interaction.
Nottelet, P., Bataille, L., Gourgues, G., Anger, R., Lartigue, C., Sirand-Pugnet, P., Marza, E., Fronzes, R., Arfi, Y.(2021) Sci Adv 7
- PubMed: 33674316 
- DOI: https://doi.org/10.1126/sciadv.abf2403
- Primary Citation of Related Structures:  
7ADJ, 7ADK, 7ADM - PubMed Abstract: 
Mycoplasma immunoglobulin binding (MIB) and mycoplasma immunoglobulin protease (MIP) are surface proteins found in the majority of mycoplasma species, acting sequentially to capture antibodies and cleave off their V H domains. Cryo-electron microscopy structures show how MIB and MIP bind to a Fab fragment in a "hug of death" mechanism. As a result, the orientation of the V L and V H domains is twisted out of alignment, disrupting the antigen binding site. We also show that MIB-MIP has the ability to promote the dissociation of the antibody-antigen complex. This system is functional in cells and protects mycoplasmas from antibody-mediated agglutination. These results highlight the key role of the MIB-MIP system in immunity evasion by mycoplasmas through an unprecedented mechanism, and open exciting perspectives to use these proteins as potential tools in the antibody field.
Organizational Affiliation: 
Structure and Function of Bacterial Nanomachines, UMR 5234, Univ. Bordeaux, CNRS, Institut Européen de Chimie et Biologie, F-33600 Pessac, France.