Mitochondrial ADCK3 Employs an Atypical Protein Kinase-like Fold to Enable Coenzyme Q Biosynthesis

Mitochondrial ADCK3 Employs an Atypical Protein Kinase-like Fold to Enable Coenzyme Q Biosynthesis MOLECULAR CELL Stefely, J. A., Reidenbach, A. G., Ulbrich, A., Oruganty, K., Floyd, B. J., Jochem, A., Saunders, J. M., Johnson, I. E., Minogue, C. E., Wrobel, R. L., Barber, G. E., Lee, D., Li, S., Kannan, N., Coon, J. J., Bingman, C. A., Pagliarini, D. J. 2015; 57 (1): 83–94

Abstract

The ancient UbiB protein kinase-like family is involved in isoprenoid lipid biosynthesis and is implicated in human diseases, but demonstration of UbiB kinase activity has remained elusive for unknown reasons. Here, we quantitatively define UbiB-specific sequence motifs and reveal their positions within the crystal structure of a UbiB protein, ADCK3. We find that multiple UbiB-specific features are poised to inhibit protein kinase activity, including an N-terminal domain that occupies the typical substrate binding pocket and a unique A-rich loop that limits ATP binding by establishing an unusual selectivity for ADP. A single alanine-to-glycine mutation of this loop flips this coenzyme selectivity and enables autophosphorylation but inhibits coenzyme Q biosynthesis in vivo, demonstrating functional relevance for this unique feature. Our work provides mechanistic insight into UbiB enzyme activity and establishes a molecular foundation for further investigation of how UbiB family proteins affect diseases and diverse biological pathways.

View details for DOI 10.1016/j.molcel.2014.11.002

View details for Web of Science ID 000347711100008

View details for PubMedID 25498144

View details for PubMedCentralID PMC4289473