Assembly mechanism and cryoEM structure of RecA recombination nucleofilaments from Streptococcus pneumoniae
| Autor: | Maud Hertzog, Thomas Noé Perry, Pauline Dupaigne, Sandra Serres, Violette Morales, Anne-Lise Soulet, Jason C Bell, Emmanuel Margeat, Stephen C Kowalczykowski, Eric Le Cam, Rémi Fronzes, Patrice Polard |
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| Rok vydání: | 2022 |
| Předmět: |
1.1 Normal biological development and functioning
Cryoelectron Microscopy DNA Pneumonia Biological Sciences Rec A Recombinases Streptococcus pneumoniae Adenosine Triphosphate Single-Stranded Underpinning research Information and Computing Sciences Escherichia coli Pneumonia & Influenza Genetics Generic health relevance Infection Lung Environmental Sciences Developmental Biology |
| Zdroj: | Nucleic acids research, vol 51, iss 6 |
| Popis: | RecA-mediated Homologous Recombination (HR) is a key mechanism for genome maintenance and plasticity in bacteria. It proceeds through RecA assembly into a dynamic filament on ssDNA, the presynaptic filament, which mediates DNA homology search and ordered DNA strand exchange. Here, we combined structural, single molecule and biochemical approaches to characterize the ATP-dependent assembly mechanism of the presynaptic filament of RecA from Streptococcus pneumoniae (SpRecA), in comparison to the Escherichia coli RecA (EcRecA) paradigm. EcRecA polymerization on ssDNA is assisted by the Single-Stranded DNA Binding (SSB) protein, which unwinds ssDNA secondary structures that block EcRecA nucleofilament growth. We report that neither of the two paralogous pneumococcal SSBs could assist SpRecA polymerization on ssDNA. Instead, we found that the conserved RadA helicase promotes this SpRecA nucleofilamentation in an ATP-dependent manner. This allowed us to solve the atomic structure of such a long native SpRecA nucleopolymer by cryoEM stabilized with ATPγS. It was found to be equivalent to the crystal structure of the EcRecA filament with a marked difference in how RecA mediates nucleotide orientation in the stretched ssDNA. Then, our results show that SpRecA and EcRecA HR activities are different, in correlation with their distinct ATP-dependent ssDNA binding modes. |
| Databáze: | OpenAIRE |
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