Conformational heterogeneity of the allosteric drug and metabolite (ADaM) site in AMP-activated protein kinase (AMPK)

• Published in: The Journal of biological chemistry Vol. 293; no. 44; pp. 16994 - 17007
• Main Authors: Gu, Xin, Bridges, Michael D., Yan, Yan, de Waal, Parker W., Zhou, X. Edward, Suino-Powell, Kelly M., Xu, H. Eric, Hubbell, Wayne L., Melcher, Karsten
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02.11.2018; American Society for Biochemistry and Molecular Biology
• Subjects: Adenosine Monophosphate - chemistry; Adenosine Monophosphate - metabolism; Allosteric Regulation; AMP-Activated Protein Kinases - chemistry; AMP-Activated Protein Kinases - genetics; AMP-Activated Protein Kinases - metabolism; Benzimidazoles - chemistry; Benzimidazoles - metabolism; Benzoates - chemistry; Benzoates - metabolism; Binding Sites; Catalytic Domain; Crystallography, X-Ray; Humans; Ligands; Molecular Biophysics; Protein Conformation; Protein Domains; DEER; ADaM site; AMP-activated kinase (AMPK); cancer; biophysics; diabetes; metabolic regulation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.RA118.004101

AMP-activated protein kinase (AMPK) is a master regulator of energy homeostasis and a promising drug target for managing metabolic diseases such as type 2 diabetes. Many pharmacological AMPK activators, and possibly unidentified physiological metabolites, bind to the allosteric drug and metabolite (ADaM) site at the interface between the kinase domain (KD) in the α-subunit and the carbohydrate-binding module (CBM) in the β-subunit. Here, using double electron–electron resonance (DEER) spectroscopy, we demonstrate that the CBM–KD interaction is partially dissociated and the interface highly disordered in the absence of pharmacological ADaM site activators as inferred from a low depth of modulation and broad DEER distance distributions. ADaM site ligands such as 991, and to a lesser degree phosphorylation, stabilize the KD–CBM association and strikingly reduce conformational heterogeneity in the ADaM site. Our findings that the ADaM site, formed by the KD–CBM interaction, can be modulated by diverse ligands and by phosphorylation suggest that it may function as a hub for integrating regulatory signals.