Biology subjects

Bley, C. J.

Publications and source records attributed to Bley, C. J..

3 recordsLinked to original sources

bioRxiv2025

A SUMO-interacting motif in the guanine nucleotide exchange factor EPAC1 is required for subcellular targeting and function

Exchange protein directly activated by cAMP (EPAC1), a multifunctional intracellular cAMP receptor, dynamically localizes to various cellular loci, engaging with diverse molecular partners to maintain cellular homeostasis. The study investigates the role of the SUMO interacting motif (SIM) in the subcellular targeting and cellular functions of EPAC1. It reveals that the SIM is a critical structural element for EPAC1s association with RanBP2/Nup358, a nucleoporin of the cytoplasmic filament component of the nuclear pore complex (NPC). Mutational disruption of EPAC1 SIM interferes with EPAC1s ability to activate its canonical effectors, small GTPases, Rap1 and Rap2, and non-canonical functions, such as the formation of nuclear condensates and cellular SUMOylation. Because SIM is also directly involved in cAMP binding, RanBP2s association with EPAC1 with the SIM attenuates EPAC1s cAMP binding affinity to generate an EPAC1 signaling microdomain with reduced cAMP sensitivity around the NPC. The coupling between EPAC1s scaffold association and cAMP binding enables EPAC1 to tune its sensitivity to stress stimuli spatially depending on the cellular locations. These findings provide novel structural insights into EPAC1 signaling, highlighting the importance of SIM in EPAC1s cellular functions and potential novel strategies for therapeutically targeting EPAC1.

cell biology↗

bioRxiv2021

Architecture of the cytoplasmic face of the nuclear pore

The nuclear pore complex (NPC) is the sole bidirectional gateway for nucleocytoplasmic transport. Despite recent progress in elucidating the NPC symmetric core architecture, the asymmetrically decorated cytoplasmic face, essential for mRNA export and a hotspot for nucleoporin-associated diseases, has remained elusive. Here, we report a composite structure of the entire human cytoplasmic face obtained by combining biochemical reconstitution, crystal structure determination, docking into cryo-electron tomographic reconstructions, and physiological validation, accounting for a third of the NPCs mass. Whereas an evolutionarily conserved [~]540 kDa hetero-hexameric cytoplasmic filament nucleoporin complex is anchored by species-specific motifs above the central transport channel, attachment of the pentameric NUP358 bundles depends on the double-ring arrangement of the coat nucleoporin complex. Our results and the predictive power of our composite structure provide a rich foundation for elucidating the molecular basis of mRNA export and nucleoporin diseases. One sentence summaryAn interdisciplinary analysis established the near-atomic molecular architecture of the cytoplasmic face of the human nuclear pore complex.

biochemistry↗

bioRxiv2021

Architecture of the linker-scaffold in the nuclear pore

The nuclear pore complex (NPC) is the sole bidirectional gateway for nucleocytoplasmic transport. Despite recent progress in elucidating the arrangement of the structured scaffold building blocks in the NPC symmetric core, their cohesion by multivalent unstructured linker proteins remained elusive. Combining biochemical reconstitution, high resolution structure determination, docking into cryo-electron tomographic reconstructions, and physiological validation, we elucidated the architecture of the entire linker-scaffold, yielding a near-atomic composite structure of the symmetric core accounting for [~]77 MDa of the human NPC. Whereas linkers generally play a rigidifying role, the linker-scaffold of the NPC provides the plasticity and robustness necessary for the reversible constriction and dilation of its central transport channel. Our results complete the structural characterization of the NPC symmetric core, providing a rich foundation for future functional studies. One sentence summaryAn interdisciplinary analysis established the near-atomic molecular architecture and evolutionary conservation of the linker-scaffold of the human nuclear pore complex.

biochemistry↗