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1.
Elife ; 112022 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-35730924

RESUMO

RecA protein mediates homologous recombination repair in bacteria through assembly of long helical filaments on ssDNA in an ATP-dependent manner. RecX, an important negative regulator of RecA, is known to inhibit RecA activity by stimulating the disassembly of RecA nucleoprotein filaments. Here we use a single-molecule approach to address the regulation of (Escherichia coli) RecA-ssDNA filaments by RecX (E. coli) within the framework of distinct conformational states of RecA-ssDNA filament. Our findings revealed that RecX effectively binds the inactive conformation of RecA-ssDNA filaments and slows down the transition to the active state. Results of this work provide new mechanistic insights into the RecX-RecA interactions and highlight the importance of conformational transitions of RecA filaments as an additional level of regulation of its biological activity.


Assuntos
Proteínas de Escherichia coli , Escherichia coli , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , DNA de Cadeia Simples/metabolismo , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Recombinases Rec A
2.
Int J Mol Sci ; 21(19)2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33036395

RESUMO

Deinococcus radiodurans (Dr) has one of the most robust DNA repair systems, which is capable of withstanding extreme doses of ionizing radiation and other sources of DNA damage. DrRecA, a central enzyme of recombinational DNA repair, is essential for extreme radioresistance. In the presence of ATP, DrRecA forms nucleoprotein filaments on DNA, similar to other bacterial RecA and eukaryotic DNA strand exchange proteins. However, DrRecA catalyzes DNA strand exchange in a unique reverse pathway. Here, we study the dynamics of DrRecA filaments formed on individual molecules of duplex and single-stranded DNA, and we follow conformational transitions triggered by ATP hydrolysis. Our results reveal that ATP hydrolysis promotes rapid DrRecA dissociation from duplex DNA, whereas on single-stranded DNA, DrRecA filaments interconvert between stretched and compressed conformations, which is a behavior shared by E. coli RecA and human Rad51. This indicates a high conservation of conformational switching in nucleoprotein filaments and suggests that additional factors might contribute to an inverse pathway of DrRecA strand exchange.


Assuntos
Trifosfato de Adenosina/química , Proteínas de Bactérias/química , Deinococcus/enzimologia , Modelos Moleculares , Conformação Molecular , Recombinases Rec A/química , Imagem Individual de Molécula , Trifosfato de Adenosina/metabolismo , Proteínas de Bactérias/metabolismo , DNA de Cadeia Simples/química , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Hidrólise , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Recombinases Rec A/metabolismo , Imagem Individual de Molécula/métodos
3.
Biochem Biophys Res Commun ; 466(3): 426-30, 2015 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-26365346

RESUMO

Deinococcus radiodurans can survive extreme doses of ionizing radiation due to the very efficient DNA repair mechanisms that are able to cope even with hundreds of double-strand breaks. RecA, the critical protein of homologous recombination in bacteria, is one of the key components of the DNA-repair system. Repair of double-strand breaks requires RecA binding to DNA and assembly of the RecA nucleoprotein helical filaments. The Escherichia coli RecA protein (EcRecA) and its interactions with DNA have been extensively studied using various approaches including single-molecule techniques, while the D. radiodurans RecA (DrRecA) remains much less characterized. However, DrRecA shows some remarkable differences from E. coli homolog. Here we combine microfluidics and single-molecule DNA manipulation with optical tweezers to follow the binding of DrRecA to long double-stranded DNA molecules and probe the mechanical properties of DrRecA nucleoprotein filaments at physiological pH. Our data provide a direct comparison of DrRecA and EcRecA binding to double-stranded DNA under identical conditions. We report a significantly faster filaments assembly as well as lower values of persistence length and contour length for DrRecA nucleoprotein filaments compared to EcRecA. Our results support the existing model of DrRecA forming more frequent and less continuous filaments relative to those of EcRecA.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Ligação a DNA/metabolismo , Deinococcus/metabolismo , Recombinases Rec A/metabolismo , Proteínas de Bactérias/química , Fenômenos Biomecânicos , Reparo do DNA , Proteínas de Ligação a DNA/química , Deinococcus/efeitos da radiação , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Técnicas Analíticas Microfluídicas , Nucleoproteínas/química , Nucleoproteínas/metabolismo , Pinças Ópticas , Multimerização Proteica , Recombinases Rec A/química
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