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Disentangling polydispersity in the PCNA-p15PAF complex, a disordered, transient and multivalent macromolecular assembly.pdf (4.43 MB)

Disentangling polydispersity in the PCNA−p15PAF complex, a disordered, transient and multivalent macromolecular assembly

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journal contribution
posted on 2018-04-30, 10:59 authored by T. N. Cordeiro, P.-C. Chen, Alfredo De Biasio, N. Sibille, F. J. Blanco, J. S. Hub, R. Crehuet, P. Bernadó
The intrinsically disordered p15PAF regulates DNA replication and repair when interacting with the Proliferating Cell Nuclear Antigen (PCNA) sliding clamp. As many interactions between disordered proteins and globular partners involved in signaling and regulation, the complex between p15PAF and trimeric PCNA is of low affinity, forming a transient complex that is difficult to characterize at a structural level due to its inherent polydispersity. We have determined the structure, conformational fluctuations, and relative population of the five species that coexist in solution by combining small-angle X-ray scattering (SAXS) with molecular modelling. By using explicit ensemble descriptions for the individual species, built using integrative approaches and molecular dynamics (MD) simulations, we collectively interpreted multiple SAXS profiles as population-weighted thermodynamic mixtures. The analysis demonstrates that the N-terminus of p15PAF penetrates the PCNA ring and emerges on the back face. This observation substantiates the role of p15PAF as a drag regulating PCNA processivity during DNA repair. Our study reveals the power of ensemble-based approaches to decode structural, dynamic, and thermodynamic information from SAXS data. This strategy paves the way for deciphering the structural bases of flexible, transient and multivalent macromolecular assemblies involved in pivotal biological processes.

History

Citation

Nucleic Acids Research, 45 (3), pp. 1501-1515

Author affiliation

/Organisation/COLLEGE OF LIFE SCIENCES/Biological Sciences/Molecular & Cell Biology

Version

  • VoR (Version of Record)

Published in

Nucleic Acids Research

Publisher

Oxford University Press

issn

0305-1048

eissn

1362-4962

Acceptance date

2016-11-16

Copyright date

2016

Available date

2018-04-30

Publisher version

https://academic.oup.com/nar/article/45/3/1501/2609480

Language

en