Structures of Asymmetric ClpX Hexamers Reveal Nucleotide-Dependent Motions in a AAA+ Protein-Unfolding Machine

Journal Article · Tue Feb 02 04:00:00 EST 2010 · Cell

DOI:https://doi.org/10.1016/j.cell.2009.09.034· OSTI ID:1006027

Glynn, Steven E; Martin, Andreas; Nager, Andrew R; Baker, Tania A; Sauer, Robert T; MIT,

ClpX is a AAA+ machine that uses the energy of ATP binding and hydrolysis to unfold native proteins and translocate unfolded polypeptides into the ClpP peptidase. The crystal structures presented here reveal striking asymmetry in ring hexamers of nucleotide-free and nucleotide-bound ClpX. Asymmetry arises from large changes in rotation between the large and small AAA+ domains of individual subunits. These differences prevent nucleotide binding to two subunits, generate a staggered arrangement of ClpX subunits and pore loops around the hexameric ring, and provide a mechanism for coupling conformational changes caused by ATP binding or hydrolysis in one subunit to flexing motions of the entire ring. Our structures explain numerous solution studies of ClpX function, predict mechanisms for pore elasticity during translocation of irregular polypeptides, and suggest how repetitive conformational changes might be coupled to mechanical work during the ATPase cycle of ClpX and related molecular machines.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE
• OSTI ID: 1006027
• Journal Information: Cell, Journal Name: Cell Journal Issue: (4) ; 11, 2009 Vol. 139; ISSN 0092-8674; ISSN CELLB5
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
ASYMMETRY
CONFORMATIONAL CHANGES
CRYSTAL STRUCTURE
ELASTICITY
HYDROLYSIS
NUCLEOTIDES
POLYPEPTIDES
PROTEINS
ROTATION
TRANSLOCATION