Michael D. Enos, Maire Gavagan, Noel Jameson, Jesse G. Zalatan, William I. Weis
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引用次数: 0
Abstract
Glycogen synthase kinase 3β (GSK-3β) targets specific signaling pathways in response to distinct upstream signals. We used structural and functional studies to dissect how an upstream phosphorylation step primes the Wnt signaling component β-catenin for phosphorylation by GSK-3β and how scaffolding interactions contribute to this reaction. Our crystal structure of GSK-3β bound to a phosphoprimed β-catenin peptide confirmed the expected binding mode of the phosphoprimed residue adjacent to the catalytic site. An aspartate phosphomimic in the priming site of β-catenin adopted an indistinguishable structure but reacted approximately 1000-fold slower than the native phosphoprimed substrate. This result suggests that substrate positioning alone is not sufficient for catalysis and that native phosphopriming interactions are necessary. We also obtained a structure of GSK-3β with an extended peptide from the scaffold protein Axin that bound with greater affinity than that of previously crystallized Axin fragments. This structure neither revealed additional contacts that produce the higher affinity nor explained how substrate interactions in the GSK-3β active site are modulated by remote Axin binding. Together, our findings suggest that phosphopriming and scaffolding produce small conformational changes or allosteric effects, not captured in the crystal structures, that activate GSK-3β and facilitate β-catenin phosphorylation. These results highlight limitations in our ability to predict catalytic activity from structure and have potential implications for the role of natural phosphomimic mutations in kinase regulation and phosphosite evolution.
期刊介绍:
"Science Signaling" is a reputable, peer-reviewed journal dedicated to the exploration of cell communication mechanisms, offering a comprehensive view of the intricate processes that govern cellular regulation. This journal, published weekly online by the American Association for the Advancement of Science (AAAS), is a go-to resource for the latest research in cell signaling and its various facets.
The journal's scope encompasses a broad range of topics, including the study of signaling networks, synthetic biology, systems biology, and the application of these findings in drug discovery. It also delves into the computational and modeling aspects of regulatory pathways, providing insights into how cells communicate and respond to their environment.
In addition to publishing full-length articles that report on groundbreaking research, "Science Signaling" also features reviews that synthesize current knowledge in the field, focus articles that highlight specific areas of interest, and editor-written highlights that draw attention to particularly significant studies. This mix of content ensures that the journal serves as a valuable resource for both researchers and professionals looking to stay abreast of the latest advancements in cell communication science.