AAA Proteins

AAA Proteins

AAA or AAA+ is an abbreviation for ATPases Associated with diverse cellular Activities. They share a common conserved module of approximately 230 amino acid residues. This is a large, functionally diverse protein family belonging to the AAA+ superfamily of ring-shaped P-loop NTPases, which exert their activity through the energy-dependent remodeling or translocation of macromolecules. These proteins are involved in a range of processes, including DNA replication, protein degradation, membrane fusion, microtubule severing, peroxisome biogenesis, signal transduction and the regulation of gene expression.

The characteristic of AAA proteins is the coupling of chemical energy by ATPase, provided by ATP hydrolysis, to mechanical force exerted on some macromolecular substrate. This usually requires a conformational change in the AAA protein in question.

AAA ATPases assemble into oligomeric assemblies (often hexamers) that form a ring-shaped structure with a central pore. These proteins produce a molecular motor that couples ATP binding and hydrolysis to changes in conformational states that can be propagated through the assembly in order to act upon a target substrate, either translocating or remodelling the substrate.

Members of the AAA family are found in all organisms and they are essential for many cellular functions.

One type of AAA Proteins are AAA Proteases, where the energy from ATP hydrolysis is used to translocate a Protein inside the Protease for degradation.

AAA-type ATPases constitute a large family of enzymes. AAA proteins are characterised by the presence of 200-250 amino-acid ATP-binding domains that contain Walker A and Walker B motifs. AAA proteins themselves belong to the superfamily of P-loop NTPases.