The structures of protein kinase A in complex with CFTR : Mechanisms of phosphorylation and noncatalytic activation

• 成果类型: Article
• 署名作者: Fiedorczuk, Karol; Iordanov, Iordan; Mihalyi, Csaba; Szollosi, Andras; Csanady, Laszlo; Chen, Jue
• 署名单位: Rockefeller University; Semmelweis University; Semmelweis University; Howard Hughes Medical Institute
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11806
• DOI: 10.1073/pnas.2409049121
• 发表日期: 2024-11-12
• 关键词: catalytic subunit; conformational-changes; chloride channel; transmembrane segment; r-domain; sites; identification; binding; roles; pka

摘要

Protein kinase A (PKA) is a key regulator of cellular functions by selectively phosphorylating numerous substrates, including ion channels, enzymes, and transcription factors. It has long served as a model system for understanding the eukaryotic kinases. Using cryoelectron microscopy, we present complex structures of the PKA catalytic subunit (PKA-C) bound to a full- length protein substrate, the cystic fibrosis transmembrane conductance regulator (CFTR)-an ion channel vital to human health. CFTR gating requires phosphorylation of its regulatory (R) domain. Unphosphorylated CFTR engages PKA-C at two locations, establishing two catalytic stations near to, but not directly involving, the R domain. This configuration, coupled with the conformational flexibility of the R domain, permits transient interactions of the eleven spatially separated phosphorylation sites. Furthermore, we determined two structures of the open- pore CFTR stabilized by PKA-C, providing a molecular basis to understand how PKA-C stimulates CFTR currents even in the absence of phosphorylation.