SLX4 (FANCP) is a multifunctional scaffold protein required for the maintenance of genome integrity. The functions of SLX4 depend on its BTB dimerization domain, but how these functions arise from SLX4 self-assembly remains elusive. SLX4 is predicted to be mainly disordered and includes SUMO interacting motifs. These characteristic features are conducive to the formation of biomolecular condensates that concentrate selectively proteins and nucleic acids into defined foci. Therefore, we used an optogenetic system to explore the capacity of SLX4 to form membraneless compartments and to understand their functions. We found that cooperative interactions mediated by the BTB dimerization domain, the SUMO interacting motifs, and the intrinsically disordered C terminal region drive the self-assembly of reversible SLX4 condensates. These micrometer-sized structures exhibited liquid-like properties. Optogenetic activation of SLX4 condensates occurred within minutes, in the absence of an exogenous source of DNA lesions. Therefore, we probed the functions that arise specifically from the condensation of SLX4. We found that the E3 SUMO ligases PIAS1, PIAS4, ZNF451, and the SUMO‐Targeted Ubiquitin Ligase RNF4 partition into SLX4 condensates and modify component proteins, including XPF, topoisomerase I, MDC1, and BRCA1. Furthermore, the control of SLX4 condensation by optogenetic activation induced the resection of newly synthesized DNA, as revealed by DNA fiber labeling and the removal of Top1-DPCs after CPT treatment. Our working hypothesis is that the nucleation of SLX4 condensates at DNA damage sites catalyzes protein group modification by the SUMO/STUBL pathway selectively, to enable the nucleolytic processing of DNA lesions and the initiation of repair.

SLX4 compartmentalizes the SUMO/Ubiquitin system to drive repair


SLX4 (FANCP) is a multifunctional scaffold protein required for the maintenance of genome integrity. The functions of SLX4 depend on its BTB dimerization domain, but how these functions arise from SLX4 self-assembly remains elusive. SLX4 is predicted to be mainly disordered and includes SUMO interacting motifs. These characteristic features are conducive to the formation of biomolecular condensates that concentrate selectively proteins and nucleic acids into defined foci. Therefore, we used an optogenetic system to explore the capacity of SLX4 to form membraneless compartments and to understand their functions. We found that cooperative interactions mediated by the BTB dimerization domain, the SUMO interacting motifs, and the intrinsically disordered C terminal region drive the self-assembly of reversible SLX4 condensates. These micrometer-sized structures exhibited liquid-like properties. Optogenetic activation of SLX4 condensates occurred within minutes, in the absence of an exogenous source of DNA lesions. Therefore, we probed the functions that arise specifically from the condensation of SLX4. We found that the E3 SUMO ligases PIAS1, PIAS4, ZNF451, and the SUMO‐Targeted Ubiquitin Ligase RNF4 partition into SLX4 condensates and modify component proteins, including XPF, topoisomerase I, MDC1, and BRCA1. Furthermore, the control of SLX4 condensation by optogenetic activation induced the resection of newly synthesized DNA, as revealed by DNA fiber labeling and the removal of Top1-DPCs after CPT treatment.  Our working hypothesis is that the nucleation of SLX4 condensates at DNA damage sites catalyzes protein group modification by the SUMO/STUBL pathway selectively, to enable the nucleolytic processing of DNA lesions and the initiation of repair.



SLX4 compartmentalizes the SUMO/Ubiquitin system to drive repair - Emile Alghoul

technical paper

SUMO (Small Ubiquitin-like Modifier) modification has recently emerged as a critical class of post translational modification (PTM), playing a major role in diverse cellular pathways in all eukaryotes. A key function of SUMO is to act as a vital counterpoise to Ubiquitination, adding a layer of control above ubiquitination including competition for targets and prevention of ubiquitin-dependent protein degradation. Phosphorylation is also regulated by SUMOylation of kinases and phosphatases. Crucially, unlike ubiquitination and phosphorylation which are controlled by thousands of genes, only 33-50 genes regulate the SUMO modification pathway in eukaryotes making SUMO an ideal experimental system to decipher the language and rules of PTMs.


Discovering how SUMO transduces environmental signals into specific physiological responses will be key to understanding this new set of fundamental ‘rules of life’ that regulate processes ranging from development to disease resistance in an ever-changing environment. This 2- day satellite meeting will highlight the established cellular role of SUMO in a range of eukaryotes in development to disease along with identifying knowledge gaps and horizon scanning. Particular emphasis will be paid to emerging technologies such as single cell techniques that will be crucial to decipher the SUMO code across eukaryotes. The meeting will consist of a series of talks from established to early career researchers who are using a variety of techniques to understand SUMO mediated cellular signalling in a range of systems (including yeast, plants and animals). Each session will end in a panel discussion with the audience hosted by the chair of the session.

Sumo Modification in Cell Signalling

This 2- day satellite meeting will highlight the established cellular role of SUMO in a range of eukaryotes in development to disease along with identifying knowledge gaps and horizon scanning. Particular emphasis will be paid to emerging technologies such as single cell techniques that will be crucial to decipher the SUMO code across eukaryotes.

Emile Alghoul

1

SHORT BIO

Presentations

SLX4 compartmentalizes the SUMO/Ubiquitin system to drive repair

Stay up to date with the latest Underline news!

PRESENTATIONS

CONFERENCES

COMPANY

RESOURCES