Unveiling the RO60-RO52 complex

[EN] The coexistence within a subcellular complex of inter -cellular proteins Ro60, responsible for preserving ncRNA quality, and Ro52, involved in intracellular proteolysis, has been a subject of ongoing debate. Employing molecular docking in tandem with experimental methods like Quartz Crystal Microbalance with Dissipation (QCM-D), Proximity Ligation Assay (PLA), and Indirect Immunofluorescence (IIF), we reveal the presence of Ro60 associating with Ro52 within the cytoplasm. This result unveils the formation of a weak transient complex with a K a approximate to (3.7 +/- 0.3) x 10 6 M -1 , where the toroid-shaped Ro60 structure interacts with the Ro52's Fc receptor, aligning horizontally within the PRY -SPRY domains of the Ro52's homodimer. The stability of this complex relies on the interaction between Ro52 chain A and specific Ro60 residues, such as K133, W177, or L185, vital in the Ro60YRNA bond. These findings bridge the role of Ro60 in YRNA management with Ro52's function in intracellular proteolysis, emphasizing the potential impact of transient complexes on cellular pathways. J. V. de J.-O. acknowledges Generalitat Valenciana, Conselleria de Innovacion, Universidades, Ciencia y Sociedad Digital, Direccion General de Ciencia e Investigacion, grants to emerging research groups CIGE/2022/59, Spain, for financial support. Rodríguez, LR.; De Julián-Ortiz, J.; Rubio De La Rúa, F.; Juste-Dolz, AM.; Angel Maquieira Catala; Mohammad-Salim, HA.; Benmetir, S... (2024). Unveiling the RO60-RO52 complex. EXCLI Journal. 23:888-903. https://doi.org/10.17179/excli2024-7141