## 5 Conclusions  
The main and unexpected result of this study is that an amyloid-like region (CTR) of the _E. coli_ Hfq protein promotes RNA annealing and induces a strong alignment of RNAs and DNA involved in the replication control of ColE1-type plasmid. Moreover, CTR stabilizes the dsDNA duplex in two regions of the ColE1 origin region. These results open perspectives to understand ColE1 plasmid DNA replication in more detail. On the basis of experiments utilizing SRCD, we propose that Hfq is mainly a negative regulator of ColE1 plasmid replication and suggest that such a proposal is compatible with otherwise ostensibly contradictory results of in vivo experiments indicating lower efficiency of transformation of _E. coli Infq_ mutants by ColE1-like plasmids and higher efficiency of synthesis of plasmid DNA. The hypothesis that alleviated inhibition of plasmid replication initiation in _hfq_ mutants might lead to runaway replication and resultant decreased viability of transformants is compatible with all results published to date and provides a possible explanation of the role of the Hfq protein in ColE1 plasmid biology.  
**Supplementary Materials:** The following are available online at [[https://www.mdpi.com/article/10.3390/app12052639/s1](https://www.mdpi.com/article/10.3390/app12052639/s1)]([https://www.mdpi.com/article/10.3390/app12052639/s1](https://www.mdpi.com/article/10.3390/app12052639/s1)), Figure S1: Observation of eventual radiation damage CTR structure after 50 spectra (\(\sim\)4 h). Figure S2: SRCD spectra of free CTR peptide (red) and full-length Hfq protein (blue).  
**Author Contributions:** Conceptualization, K.K., F.T., G.W. and V.A.; formal analysis, F.W., K.K., F.T. and K.M.; funding acquisition, K.K., G.W. and V.A.; investigation, F.W., K.M., G.W. and V.A.; methodology, F.W., F.T., K.M. and V.A.; project administration, G.W. and V.A.; resources, G.W. and V.A.; software, F.W., F.T. and K.M.; supervision, F.W., G.W. and V.A.; validation, F.W.; visualization, F.W., F.T., K.M. and V.A.; writing--original draft, F.W., K.K., F.T., K.M., G.W. and V.A.; writing--review & editing, F.W., K.K., G.W. and V.A. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by CNRS, CEA (VA), synchrotron SOLEIL (FW), National Science Center (Poland) (grant number 2016/21/N/NZ1/02850) (KK), and University of Gdansk (task grant no. 531-D020-D242-21) (GW). SRCD measurements on DISCO beamline at the SOLEIL synchrotron were performed under proposal 20210003. This study contributes to the IdEx Universite de Paris ANR-18-IDEX-0001 (VA). This work was also supported by a public grant overseen by the French National Research Agency (ANR) as part of the \"Investissement d'Avenir\" program, through the \"ADI 2021\" project funded by the IDEX Paris-Saclay, ANR-11-IDEX-0003-02 (FT). Support from National Agency for Academic Exchange (Poland) (grant no. BPN/FRC/2021/1/00054/DEC/1) (FT) is acknowledged.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The SRCD data that support the findings of this study are available on request from the corresponding authors.  
**Acknowledgments:** We are grateful to [PERSON] (LLB, CEA Saclay, France) for technical support, to [PERSON] and [PERSON] (LBPA, ENS Paris Saclay, France) for DNA analysis after UV exposition, and to [PERSON] (SDMT, SD, USA) for critical reading of the manuscript.  
**Conflicts of Interest:** The authors declare no conflict of interest.