Fronzes Lab

Structure & function

of bacterial nanomachines


Welcome to the Fronzes Lab

The Team Structure and function of bacterial nanomachines is part of the UMR 5234 Microbiologie fondamentale et pathogénicité and is located in the Institut Européen de Chimie et Biologie in Pessac, France


Our research themes

Bacterial type VI

secretion systems

Metabolic adaptability of bacterial pathogens

Bacterial transformation


Other bacterial nanomachines

Latest News

The mycoplasma surface proteins MIB and MIP promote the dissociation of the antibody-antigen interaction



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 VH 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 VL and VH 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.


Published in Science Advances


Nottelet P, Bataille L, Gourgues G, Anger R, Lartigue C, Sirand-Pugnet P, Marza E, Fronzes R, Arfi Y.

The mycoplasma surface proteins MIB and MIP promote the dissociation of the antibody-antigen interaction.

Sci Adv. 2021 Mar 5;7(10)

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(3) These are first in depth structural and mechanistic insights of T6SS Rhs delivery, together with the Pseudomonas Rhs structure solved by the labs of J.Whitney and S.Raunser (

Finally out !! 😀🍾🍾
Congratulations to @DukasJu @leotrosa @jchamotrooke @fronzes_lab for this huge work that reports the structure of the Photorhabdus Rhs effector, and how it is loaded onto the #T6SS, and processed to release the encapsulated toxin !

Very happy to share our latest T6SS related paper in ⁦@NatureComms⁩ . Fantastic collaboration with ⁦@CascalesLab⁩ ⁦@DukasJu⁩
⁦@INSB_CNRS⁩ ⁦@iecb_bordeaux⁩ ⁦@univbordeaux⁩ #MFP_lab
CryoEM data from ⁦⁦@EArctica⁩

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