ATP-driven membrane binding and polymerization of bacterial actin MreB promotes local membrane fluidization

Abstract

The bacterial actin homolog MreB plays a key role in rod cell shape determination. We recently showed that MreB from the Gram-positive bacterium Geobacillus stearothermophilus (MreBGs) polymerizes into straight pairs of protofilaments in the presence of both ATP and a lipid surface. Membrane interaction is thought to be mediated by electrostatic interactions with anionic lipids, with final anchoring relying on two spatially close hydrophobic motifs that protrude from the MreBGs monomers, forming a putative membrane-insertion domain. Here, we determined the binding properties of ATP and ADP to MreBGs using fluorescence anisotropy and monitored ATP-mediated binding and polymer formation on lipid bilayers using liposome-binding assays and atomic force microscopy, respectively. Finally, we used solid-state NMR to visualize the interaction between the membrane and MreBGs at the atomic level. Our findings reveal that divalent cations are required for nucleotide binding and that, unlike eukaryotic actin, MreBGs has similar affinity for both ATP and ADP. We also show that monomeric MreBGs establishes peripheral contacts with the membrane likely through electrostatic interactions, while Mg⋅ATP-induced MreBGs filaments insert into the lipid bilayer without interfering with the membrane lamellar phase and have a significant local fluidifying effect.

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BibTeX RIS

BibTeX

@article{adriaans2026atpdriven,
  title = {{ATP-driven membrane binding and polymerization of bacterial actin MreB promotes local membrane fluidization}},
  author = {Ingrid E Adriaans and Ana Álvarez-Mena and Céline Dinet and Estelle Morvan and Kee Siang Lim and Erick J Dufourc and Richard Wong and Arnaud Chastanet and Alphée Michelot and Rut Carballido-López and Birgit Habenstein},
  journal = {Biophysical Journal},
  year = {2026},
  month = jun,
  doi = {10.1016/j.bpj.2026.06.003},
  url = {https://hal.science/hal-05784575v1},
  note = {CC BY 4.0},
}

RIS

TY  - JOUR
TI  - ATP-driven membrane binding and polymerization of bacterial actin MreB promotes local membrane fluidization
AU  - Ingrid E Adriaans
AU  - Ana Álvarez-Mena
AU  - Céline Dinet
AU  - Estelle Morvan
AU  - Kee Siang Lim
AU  - Erick J Dufourc
AU  - Richard Wong
AU  - Arnaud Chastanet
AU  - Alphée Michelot
AU  - Rut Carballido-López
AU  - Birgit Habenstein
PY  - 2026
DA  - 2026/06/03
JO  - Biophysical Journal
DO  - 10.1016/j.bpj.2026.06.003
UR  - https://hal.science/hal-05784575v1
AB  - The bacterial actin homolog MreB plays a key role in rod cell shape determination. We recently showed that MreB from the Gram-positive bacterium Geobacillus stearothermophilus (MreBGs) polymerizes into straight pairs of protofilaments in the presence of both ATP and a lipid surface. Membrane interaction is thought to be mediated by electrostatic interactions with anionic lipids, with final anchoring relying on two spatially close hydrophobic motifs that protrude from the MreBGs monomers, forming a putative membrane-insertion domain. Here, we determined the binding properties of ATP and ADP to MreBGs using fluorescence anisotropy and monitored ATP-mediated binding and polymer formation on lipid bilayers using liposome-binding assays and atomic force microscopy, respectively. Finally, we used solid-state NMR to visualize the interaction between the membrane and MreBGs at the atomic level. Our findings reveal that divalent cations are required for nucleotide binding and that, unlike eukaryotic actin, MreBGs has similar affinity for both ATP and ADP. We also show that monomeric MreBGs establishes peripheral contacts with the membrane likely through electrostatic interactions, while Mg⋅ATP-induced MreBGs filaments insert into the lipid bilayer without interfering with the membrane lamellar phase and have a significant local fluidifying effect.
SN  - 0006-3495
SN  - 1542-0086
ER  -

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