Kalle Anagha, Wu Jian, Tawfeeq Caesar, Kornev Alexandr P, Veglia Gianluigi, Maillard Rodrigo, Taylor Susan S, Jonniya Nisha Amarnath
Advanced Academic Program, Johns Hopkins University, Washington, DC 20001.
Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093.
Proc Natl Acad Sci U S A. 2025 Jun 17;122(24):e2502898122. doi: 10.1073/pnas.2502898122. Epub 2025 Jun 12.
Cushing's syndrome (CS) is an abnormal condition characterized by elevated cortisol levels, often resulting from genetic alterations in the gene, which encodes the catalytic subunit of cAMP-dependent protein kinase A (PKA-C). The most common CS mutation, L205R, lies at the P + 1 loop. Understanding how this mutation alters the internal allosteric network within PKA-C and changes nucleotide and substrate cooperativity is a major goal. Using molecular dynamics (MD) simulations and protein residue networks based on local spatial pattern (LSP) method, we compare crystal structures of wild-type PKA-C and L205R. Our findings indicate that L205R not only locally disrupts the P + 1 hydrophobic pocket, leading to the displacement of the P + 1-residue and altered substrate specificity, but also has long-range effects in the linker connecting the A helix to β strand 1. The MD simulations and LSP analyses also reveal critical changes at the phosphoryl transfer site. Some of these changes are captured in the L205R crystal structure while others are not. With this strategy, we also show how the dynamics of local and distal allosteric networks are differentially influenced by backbone and side-chain dynamics.
库欣综合征（CS）是一种以皮质醇水平升高为特征的异常病症，通常由编码环磷酸腺苷依赖性蛋白激酶A（PKA-C）催化亚基的基因发生遗传改变所致。最常见的CS突变L205R位于P + 1环。了解这种突变如何改变PKA-C内的内部变构网络以及改变核苷酸和底物协同性是一个主要目标。我们使用基于局部空间模式（LSP）方法的分子动力学（MD）模拟和蛋白质残基网络，比较野生型PKA-C和L205R的晶体结构。我们的研究结果表明，L205R不仅局部破坏P + 1疏水口袋，导致P + 1残基移位并改变底物特异性，而且在连接A螺旋与β链1的连接区具有远程效应。MD模拟和LSP分析还揭示了磷酸转移位点的关键变化。其中一些变化在L205R晶体结构中有所体现，而其他变化则未体现。通过这种策略，我们还展示了局部和远端变构网络的动力学如何受到主链和侧链动力学的不同影响。
