title: Conformational transitions regulate the exposure of a DNA-binding domain in the RuvBL1-RuvBL2 complex.
abstract: RuvBL1 and RuvBL2, also known as Pontin and Reptin, are AAA+ proteins essential in small nucleolar ribonucloprotein biogenesis, chromatin remodelling, nonsense-mediated messenger RNA decay and telomerase assembly, among other functions. They are homologous to prokaryotic RuvB, forming single- and double-hexameric rings; however, a DNA binding domain II (DII) is inserted within the AAA+ core. Despite their biological significance, questions remain regarding their structure. Here, we report cryo-electron microscopy structures of human double-ring RuvBL1-RuvBL2 complexes at ∼15 Å resolution. Significantly, we resolve two coexisting conformations, compact and stretched, by image classification techniques. Movements in DII domains drive these conformational transitions, extending the complex and regulating the exposure of DNA binding regions. DII domains connect with the AAA+ core and bind nucleic acids, suggesting that these conformational changes could impact the regulation of RuvBL1-RuvBL2 containing complexes. These findings resolve some of the controversies in the structure of RuvBL1-RuvBL2 by revealing a mechanism that extends the complex by adjustments in DII.
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maetzu 9, 28040 Madrid, Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: López-Perrote
authors.forename: Hugo
authors.initials: H
authors.lastname: Muñoz-Hernández
authors.forename: David
authors.initials: D
authors.lastname: Gil
authors.forename: Oscar
authors.initials: O
authors.lastname: Llorca
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D004265:DNA Helicases / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D008958:Models, Molecular; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D000074183:ATPases Associated with Diverse Cellular Activities; D004265:DNA Helicases; C486549:RUVBL1 protein, human; C122079:RUVBL2 protein, human