title: The elusive middle domain of Hsp104 and ClpB: location and function.
abstract: Hsp104 in yeast and ClpB in bacteria are homologous, hexameric AAA+ proteins and Hsp100 chaperones, which function in the stress response as ring-translocases that drive protein disaggregation and reactivation. Both Hsp104 and ClpB contain a distinctive coiled-coil middle domain (MD) inserted in the first AAA+ domain, which distinguishes them from other AAA+ proteins and Hsp100 family members. Here, we focus on recent developments concerning the location and function of the MD in these hexameric molecular machines, which remains an outstanding question. While the atomic structure of the hexameric assembly of Hsp104 and ClpB remains uncertain, recent advances have illuminated that the MD is critical for the intrinsic disaggregase activity of the hexamer and mediates key functional interactions with the Hsp70 chaperone system (Hsp70 and Hsp40) that empower protein disaggregation.
authors.affiliation: Department of Biochemistry and Biophysics, Perelman School of Medicine at The University of Pennsylvania, 805b Stellar-Chance Laboratories, 422 Curie Boulevard, Philadelphia, PA 19104, USA.
authors.forename: Morgan E
authors.initials: ME
authors.lastname: Desantis
authors.forename: James
authors.initials: J
authors.lastname: Shorter
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006360:Heat-Shock Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D040681:Structural Homology, Protein
chemical_list: D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D049071:Endopeptidase Clp; C069775:ClpB protein, E coli