The Bacterial ATPase SecA Functions as a Monomer in Protein Translocation

Abstract

The ATPase SecA drives the post-translational translocation of proteins through the SecY channel in the bacterial inner membrane. SecA is a dimer that can dissociate into monomers under certain conditions. To address the functional importance of the monomeric state, we generated an Escherichia coli SecA mutant that is almost completely monomeric (>99%), consistent with predictions from the crystal structure of Bacillus subtilis SecA. In vitro, the monomeric derivative retained significant activity in various assays, and in vivo, it sustained 85% of the growth rate of wild type cells and reduced the accumulation of precursor proteins in the cytoplasm. Disulfide cross-linking in intact cells showed that mutant SecA is monomeric and that even its parental dimeric form is dissociated. Our results suggest that SecA functions as a monomer during protein translocation in vivo.

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BibTeX

@article{or2026bacterial,
  title = {{The Bacterial ATPase SecA Functions as a Monomer in Protein Translocation}},
  author = {Eran Or and Dana Boyd and Stéphanie Gon and Jonathan Beckwith and Tom Rapoport},
  journal = {Journal of Biological Chemistry},
  year = {2026},
  month = oct,
  doi = {10.1074/jbc.m413947200},
  url = {https://hal.science/hal-05843712v1},
  note = {CC BY},
}

RIS

TY  - JOUR
TI  - The Bacterial ATPase SecA Functions as a Monomer in Protein Translocation
AU  - Eran Or
AU  - Dana Boyd
AU  - Stéphanie Gon
AU  - Jonathan Beckwith
AU  - Tom Rapoport
PY  - 2026
DA  - 2026/10/29
JO  - Journal of Biological Chemistry
DO  - 10.1074/jbc.m413947200
UR  - https://hal.science/hal-05843712v1
AB  - The ATPase SecA drives the post-translational translocation of proteins through the SecY channel in the bacterial inner membrane. SecA is a dimer that can dissociate into monomers under certain conditions. To address the functional importance of the monomeric state, we generated an Escherichia coli SecA mutant that is almost completely monomeric (>99%), consistent with predictions from the crystal structure of Bacillus subtilis SecA. In vitro, the monomeric derivative retained significant activity in various assays, and in vivo, it sustained 85% of the growth rate of wild type cells and reduced the accumulation of precursor proteins in the cytoplasm. Disulfide cross-linking in intact cells showed that mutant SecA is monomeric and that even its parental dimeric form is dissociated. Our results suggest that SecA functions as a monomer during protein translocation in vivo.
SN  - 0021-9258
SN  - 1083-351X
ER  -

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