Abstract
Bacterial RecA protein oligomerizes on single-stranded DNA (ssDNA) in the presence of ATP to form an active filament, RecA*, which is essential for homologous recombination and the activation of bacterial DNA damage response (SOS response). Despite extensive studies on the structure and function of RecA and RecA*, the exact function of the RecA flexible C-terminal tail remains poorly understood. Here, we report the crystal structure of the full-length RecA protein from K. pneumoniae, revealing that the C-terminal tail adopts a β-strand conformation. The negatively charged C-terminal tail is observed to interact with two positively charged conserved residues in the RecA core ATPase domain. We also demonstrate that the C-terminal tail of the E. coli and K. pneumoniae RecA inhibits the formation of RecA filament, DNA binding, and DNA strand exchange during homologous recombination, but promotes LexA self-cleavage as a co-protease and enhances the SOS response induced by mitomycin and ciprofloxacin. Our results provide mechanistic insights into the regulatory function of the RecA C-terminal tail in genome maintenance and DNA damage response.
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Data availability
The atomic coordinates and structure factors have been deposited in the Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB, https://www.rcsb.org/) with the following accession codes: 9UOO. Source data for the graphs are available in the Supplementary Data.
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Acknowledgements
We thank the beamline staff of BL02U1 at Shanghai Synchrotron Radiation Facility for their help with data collection. We thank the staff members of the Large-scale Protein Preparation System at the National Facility for Protein Science in Shanghai (NFPS), Shanghai Advanced Research Institute, Chinese Academy of Sciences, China, for providing technical support and assistance in data collection and analysis. We thank Yuchen Zhang in the Center of Cryo-Electron Microscopy (CCEM), Zhejiang University for her technical assistance on Transmission Electron Microscopy. Figure 1B (left), 2A, 3A, 4A, 6A, and 7B were created with biorender.com(https://BioRender.com/4neox63, https://BioRender.com/02ng0vb, https://BioRender.com/214bz8b, https://BioRender.com/6p874qp, https://BioRender.com/9pcplor, https://BioRender.com/goa6tob), with licenses. This work was supported by the National Natural Science Foundation of China (32371250 to C.Z.) and the Key Project of Natural Science Foundation of Zhejiang Province (LZ24C050002 to C.Z.).
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C.Z. and L.S. designed research; L.S., X.L., F.W., M.W., Y.L., Y.Z., A.G., L.C., Y.G., M.X., and C.Z. performed experiments; L.S., N.D., Y.F., and C.Z. analyzed data; L.S. and C.Z. wrote the paper.
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Su, L., Li, X., Wang, F. et al. Mechanistic insights into the structure and function of the RecA C-terminal tail. Commun Biol (2026). https://doi.org/10.1038/s42003-026-09788-4
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DOI: https://doi.org/10.1038/s42003-026-09788-4
