Modulation of Pantothenate Kinase 3 Activity by Small Molecules that Interact with the Substrate/Allosteric Regulatory Domain

SummaryPantothenate kinase (PanK) catalyzes the rate-controlling step in coenzyme A (CoA) biosynthesis. PanK3 is stringently regulated by acetyl-CoA and uses an ordered kinetic mechanism with ATP as the leading substrate. Biochemical analysis of site-directed mutants indicates that pantothenate binds in a tunnel adjacent to the active site that is occupied by the pantothenate moiety of the acetyl-CoA regulator in the PanK3⋅acetyl-CoA binary complex. A high-throughput screen for PanK3 inhibitors and activators was applied to a bioactive compound library. Thiazolidinediones, sulfonylureas and steroids were inhibitors, and fatty acyl-amides and tamoxifen were activators. The PanK3 activators and inhibitors either stimulated or repressed CoA biosynthesis in HepG2/C3A cells. The flexible allosteric acetyl-CoA regulatory domain of PanK3 also binds the substrates, pantothenate and pantetheine, and small molecule inhibitors and activators to modulate PanK3 activity.

Graphical AbstractFigure optionsDownload full-size imageDownload high-quality image (482 K)Download as PowerPoint slideHighlights► PanK3 binds pantothenate within the acetyl-CoA regulatory site ► Thiazolidinediones and sulfonylureas are PanK3 inhibitors ► Tamoxifen and fatty acyl amides are PanK3 activators ► Flexible allosteric acetyl-CoA regulatory domain also binds substrates and small molecular inhibitors and activators