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Structures of 9-1-1 DNA checkpoint clamp loading at gaps from start to finish and ramification on biology

Rad24-RFC (replication factor C) loads the 9-1-1 checkpoint clamp onto the recessed 5′ ends by binding a 5′ DNA at an external surface site and threading the 3′ single-stranded DNA (ssDNA) into 9-1-1. We find here that Rad24-RFC loads 9-1-1 onto DNA gaps in preference to a recessed 5′ end, thus pres...

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Detalles Bibliográficos
Autores principales: Zheng, Fengwei, Georgescu, Roxana E., Yao, Nina Y., O’Donnell, Michael E., Li, Huilin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10529453/
https://www.ncbi.nlm.nih.gov/pubmed/37392384
http://dx.doi.org/10.1016/j.celrep.2023.112694
Descripción
Sumario:Rad24-RFC (replication factor C) loads the 9-1-1 checkpoint clamp onto the recessed 5′ ends by binding a 5′ DNA at an external surface site and threading the 3′ single-stranded DNA (ssDNA) into 9-1-1. We find here that Rad24-RFC loads 9-1-1 onto DNA gaps in preference to a recessed 5′ end, thus presumably leaving 9-1-1 on duplex 3′ ss/double-stranded DNA (dsDNA) after Rad24-RFC ejects from DNA. We captured five Rad24-RFC-9-1-1 loading intermediates using a 10-nt gap DNA. We also determined the structure of Rad24-RFC–9-1-1 using a 5-nt gap DNA. The structures reveal that Rad24-RFC is unable to melt DNA ends and that a Rad24 loop limits the dsDNA length in the chamber. These observations explain Rad24-RFC’s preference for a preexisting gap of over 5-nt ssDNA and suggest a direct role of the 9-1-1 in gap repair with various TLS (translesion synthesis) polymerases in addition to signaling the ATR kinase.