PDBsum entry 1r6b

Hydrolase

PDB id: 1r6b

Contents

Protein chain

704 a.a. *

Ligands

ADP ×2

Metals

_MG ×3

Waters ×60

* Residue conservation analysis

PDB id:

1r6b

Name:

Hydrolase

Title:

High resolution crystal structure of clpa

Structure:

Clpa protein. Chain: x. Engineered: yes. Mutation: yes

Source:

Escherichia coli. Organism_taxid: 562. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.25Å R-factor: 0.235 R-free: 0.278

Authors:

D.Xia,M.R.Maurizi,F.Guo,S.K.Singh,L.Esser

Key ref:

D.Xia et al. (2004). Crystallographic investigation of peptide binding sites in the N-domain of the ClpA chaperone. J Struct Biol, 146, 166-179. PubMed id: 15037248 DOI: 10.1016/j.jsb.2003.11.025

Date:

15-Oct-03 Release date: 24-Aug-04

Protein chain

P0ABH9  (CLPA_ECOLI) -  ATP-dependent Clp protease ATP-binding subunit ClpA from Escherichia coli (strain K12)

Seq: 758 a.a.

Struc: 704 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1016/j.jsb.2003.11.025

J Struct Biol 146:166-179 (2004)

PubMed id: 15037248

Crystallographic investigation of peptide binding sites in the N-domain of the ClpA chaperone.

D.Xia, L.Esser, S.K.Singh, F.Guo, M.R.Maurizi.

ABSTRACT

Escherichia coli ClpA, an Hsp100/Clp chaperone and an integral component of the ATP-dependent ClpAP protease, participates in the dissolution and degradation of regulatory proteins and protein aggregates. ClpA consists of three functional domains: an N-terminal domain and two ATPase domains, D1 and D2. The N-domain is attached to D1 by a mobile linker and is made up of two tightly bound, identically folded alpha-helical bundles related by a pseudo 2-fold symmetry. Between the halves of the pseudo-dimer is a large flexible acidic loop that becomes better ordered upon binding of the small adaptor protein, ClpS. We have identified a number of structural features in the N-domain, including a Zn(++) binding motif, several interfaces for binding to ClpS, and a prominent hydrophobic surface area that binds peptides in different configurations. These structural motifs may contribute to binding of protein or peptide substrates with weak affinity and broad specificity. Kinetic studies comparing wild-type ClpA to a mutant ClpA with its N-domain deleted show that the N-domains contribute to the binding of a non-specific protein substrate but not of a folded substrate with the specific SsrA recognition tag. A functional model is proposed in which the N-domains in ClpA function as tentacles to weakly hold on to proteins thereby enhancing local substrate concentration.