Molecular mechanisms of assembly and TRIP13-mediated remodeling of the human Shieldin complex.
Proc Natl Acad Sci U S A
; 118(8)2021 02 23.
Article
en En
| MEDLINE
| ID: mdl-33597306
ABSTRACT
The Shieldin complex, composed of REV7, SHLD1, SHLD2, and SHLD3, protects DNA double-strand breaks (DSBs) to promote nonhomologous end joining. The AAA+ ATPase TRIP13 remodels Shieldin to regulate DNA repair pathway choice. Here we report crystal structures of human SHLD3-REV7 binary and fused SHLD2-SHLD3-REV7 ternary complexes, revealing that assembly of Shieldin requires fused SHLD2-SHLD3 induced conformational heterodimerization of open (O-REV7) and closed (C-REV7) forms of REV7. We also report the cryogenic electron microscopy (cryo-EM) structures of the ATPγS-bound fused SHLD2-SHLD3-REV7-TRIP13 complexes, uncovering the principles underlying the TRIP13-mediated disassembly mechanism of the Shieldin complex. We demonstrate that the N terminus of REV7 inserts into the central channel of TRIP13, setting the stage for pulling the unfolded N-terminal peptide of C-REV7 through the central TRIP13 hexameric channel. The primary interface involves contacts between the safety-belt segment of C-REV7 and a conserved and negatively charged loop of TRIP13. This process is mediated by ATP hydrolysis-triggered rotatory motions of the TRIP13 ATPase, thereby resulting in the disassembly of the Shieldin complex.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Adenosina Trifosfato
/
Proteínas de Ciclo Celular
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Proteínas de Unión al ADN
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Proteínas Mad2
/
ATPasas Asociadas con Actividades Celulares Diversas
Límite:
Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2021
Tipo del documento:
Article