AAA ATPases as therapeutic targets: Structure, functions, and small-molecule inhibitors

ATPases Associated with Diverse Cellular Activity (AAA ATPase) are essential enzymes found in all organisms. They are involved in various processes such as DNA replication, protein degradation, membrane fusion, microtubule serving, peroxisome biogenesis, signal transduction, and the regulation of gene expression. Due to the importance of AAA ATPases, several researchers identified and developed small-molecule inhibitors against these enzymes. We discuss six AAA ATPases that are potential drug targets and have well-developed inhibitors. We compare available structures that suggest significant differences of the ATP binding pockets among the AAA ATPases with or without ligand. The distances from ADP to the His20 in the His-Ser-His motif and the Arg finger (Arg353 or Arg378) in both RUVBL1/2 complex structures bound with or without ADP have significant differences, suggesting dramatically different interactions of the binding site with ADP. Taken together, the inhibitors of six well-studied AAA ATPases and their structural information suggest further development of specific AAA ATPase inhibitors due to difference in their structures. Future chemical biology coupled with proteomic approaches could be employed to develop variant specific, complex specific, and pathway specific inhibitors or activators for AAA ATPase proteins.

p97: An Emerging Target for Cancer, Neurodegenerative Diseases, and Viral Infections

The AAA+ ATPase, p97, also referred to as VCP, plays an essential role in cellular homeostasis by regulating endoplasmic reticulum-associated degradation (ERAD), mitochondrial-associated degradation (MAD), chromatin-associated degradation, autophagy, and endosomal trafficking. Mutations in p97 have been linked to a number of neurodegenerative diseases, and overexpression of wild type p97 is observed in numerous cancers. Furthermore, p97 activity has been shown to be essential for the replication of certain viruses, including poliovirus, herpes simplex virus (HSV), cytomegalovirus (CMV), and influenza. Taken together, these observations highlight the potential for targeting p97 as a therapeutic approach in neurodegeneration, cancer, and certain infectious diseases. This Perspective reviews recent advances in the discovery of small molecule inhibitors of p97, their optimization and characterization, and therapeutic potential.