PDBsum entry 4lj9

Chaperone

PDB id: 4lj9

Contents

Protein chain

332 a.a.

Ligands

ACP

Metals

_MG ×2

Waters ×216

PDB id:

4lj9

Name:

Chaperone

Title:

Clpb nbd2 r621q from t. Thermophilus in complex with amppcp

Structure:

Chaperone protein clpb. Chain: a. Fragment: nucleotide binding domain 2, unp residues 520-854. Engineered: yes. Mutation: yes

Source:

Thermus thermophilus. Organism_taxid: 300852. Strain: hb8. Gene: clpb. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.70Å R-factor: 0.210 R-free: 0.244

Authors:

C.Zeymer,T.R.M.Barends,N.D.Werbeck,I.Schlichting,J.Reinstein

Key ref:

C.Zeymer et al. (2014). Elements in nucleotide sensing and hydrolysis of the AAA+ disaggregation machine ClpB: a structure-based mechanistic dissection of a molecular motor. Acta Crystallogr D Biol Crystallogr, 70, 582-595. PubMed id: 24531492 DOI: 10.1107/S1399004713030629

Date:

04-Jul-13 Release date: 12-Feb-14

Protein chain

Q9RA63  (CLPB_THET8) -  Chaperone protein ClpB from Thermus thermophilus (strain ATCC 27634 / DSM 579 / HB8)

Seq: 854 a.a.

Struc: 332 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1107/S1399004713030629

Acta Crystallogr D Biol Crystallogr 70:582-595 (2014)

PubMed id: 24531492

Elements in nucleotide sensing and hydrolysis of the AAA+ disaggregation machine ClpB: a structure-based mechanistic dissection of a molecular motor.

C.Zeymer, T.R.Barends, N.D.Werbeck, I.Schlichting, J.Reinstein.

ABSTRACT

ATPases of the AAA+ superfamily are large oligomeric molecular machines that remodel their substrates by converting the energy from ATP hydrolysis into mechanical force. This study focuses on the molecular chaperone ClpB, the bacterial homologue of Hsp104, which reactivates aggregated proteins under cellular stress conditions. Based on high-resolution crystal structures in different nucleotide states, mutational analysis and nucleotide-binding kinetics experiments, the ATPase cycle of the C-terminal nucleotide-binding domain (NBD2), one of the motor subunits of this AAA+ disaggregation machine, is dissected mechanistically. The results provide insights into nucleotide sensing, explaining how the conserved sensor 2 motif contributes to the discrimination between ADP and ATP binding. Furthermore, the role of a conserved active-site arginine (Arg621), which controls binding of the essential Mg2+ ion, is described. Finally, a hypothesis is presented as to how the ATPase activity is regulated by a conformational switch that involves the essential Walker A lysine. In the proposed model, an unusual side-chain conformation of this highly conserved residue stabilizes a catalytically inactive state, thereby avoiding unnecessary ATP hydrolysis.