Mechanistic insight into the assembly of the HerA-NurA helicase-nuclease DNA end resection complex.
Nucleic Acids Res
; 45(20): 12025-12038, 2017 Nov 16.
Article
em En
| MEDLINE
| ID: mdl-29149348
ABSTRACT
The HerA-NurA helicase-nuclease complex cooperates with Mre11 and Rad50 to coordinate the repair of double-stranded DNA breaks. Little is known, however, about the assembly mechanism and activation of the HerA-NurA. By combining hybrid mass spectrometry with cryo-EM, computational and biochemical data, we investigate the oligomeric formation of HerA and detail the mechanism of nucleotide binding to the HerA-NurA complex from thermophilic archaea. We reveal that ATP-free HerA and HerA-DNA complexes predominantly exist in solution as a heptamer and act as a DNA loading intermediate. The binding of either NurA or ATP stabilizes the hexameric HerA, indicating that HerA-NurA is activated by substrates and complex assembly. To examine the role of ATP in DNA translocation and processing, we investigated how nucleotides interact with the HerA-NurA. We show that while the hexameric HerA binds six nucleotides in an 'all-or-none' fashion, HerA-NurA harbors a highly coordinated pairwise binding mechanism and enables the translocation and processing of double-stranded DNA. Using molecular dynamics simulations, we reveal novel inter-residue interactions between the external ATP and the internal DNA binding sites. Overall, here we propose a stepwise assembly mechanism detailing the synergistic activation of HerA-NurA by ATP, which allows efficient processing of double-stranded DNA.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
DNA Helicases
/
Proteínas Arqueais
/
DNA Arqueal
/
Desoxirribonucleases
Idioma:
En
Revista:
Nucleic Acids Res
Ano de publicação:
2017
Tipo de documento:
Article