Comparative Analysis of the Structure and Function of AAA+ Motors ClpA, ClpB, and Hsp104: Common Threads and Disparate Functions.

Cellular proteostasis involves not only the expression of proteins in response to environmental needs, but also the timely repair or removal of damaged or unneeded proteins. AAA+ motor proteins are critically involved in these pathways. Here, we review the structure and function of AAA+ proteins ClpA, ClpB, and Hsp104.

Avidity for Polypeptide Binding by Nucleotide-Bound Hsp104 Structures.

Recent Hsp104 structural studies have reported both planar and helical models of the hexameric structure. The conformation of Hsp104 monomers within the hexamer is affected by nucleotide ligation. After nucleotide-driven hexamer formation, Hsp104-catalyzed disruption of protein aggregates requires binding to the peptide substrate.

Escherichia coli ClpB is a non-processive polypeptide translocase.

Escherichia coli caseinolytic protease (Clp)B is a hexameric AAA+ [expanded superfamily of AAA (ATPase associated with various cellular activities)] enzyme that has the unique ability to catalyse protein disaggregation. Such enzymes are essential for proteome maintenance. Based on structural comparisons to homologous enzymes involved in ATP-dependent proteolysis and clever protein engineering strategies, it has been reported that ClpB translocates polypeptide through its axial channel.