PDBsum entry 3j3u

Chaperone

PDB id: 3j3u

Contents

Protein chains

(+ 0 more) 94 a.a.

(+ 0 more) 798 a.a.

PDB id:

3j3u

Name:

Chaperone

Title:

Structural dynamics of the meca-clpc complex revealed by cryo-em

Structure:

Adapter protein meca 1. Chain: 1, 2, 3, 4, 5, 6. Engineered: yes. Negative regulator of genetic competence clpc/mecb. Chain: a, b, c, d, e, f. Engineered: yes. Mutation: yes

Source:

Bacillus subtilis. Organism_taxid: 224308. Strain: 168. Gene: bsu11520, meca. Expressed in: escherichia coli. Expression_system_taxid: 562. Gene: bsu00860, clpc, mecb.

Authors:

J.Liu,Z.Mei,N.Li,Y.Qi,Y.Xu,Y.Shi,F.Wang,J.Lei,N.Gao

Key ref:

J.Liu et al. (2013). Structural dynamics of the MecA-ClpC complex: a type II AAA+ protein unfolding machine. J Biol Chem, 288, 17597-17608. PubMed id: 23595989 DOI: 10.1074/jbc.M113.458752

Date:

18-Apr-13 Release date: 15-May-13

Protein chains

P37958  (MECA1_BACSU) -  Adapter protein MecA 1 from Bacillus subtilis (strain 168)

Seq: 218 a.a.

Struc: 94 a.a.

Protein chains

P37571  (CLPC_BACSU) -  Negative regulator of genetic competence ClpC/MecB from Bacillus subtilis (strain 168)

Seq: 810 a.a.

Struc: 798 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains 1, 2, 3, 4, 5, 6, A, B, C, D, E, F: E.C.?

DOI no: 10.1074/jbc.M113.458752

J Biol Chem 288:17597-17608 (2013)

PubMed id: 23595989

Structural dynamics of the MecA-ClpC complex: a type II AAA+ protein unfolding machine.

J.Liu, Z.Mei, N.Li, Y.Qi, Y.Xu, Y.Shi, F.Wang, J.Lei, N.Gao.

ABSTRACT

The MecA-ClpC complex is a bacterial type II AAA(+) molecular machine responsible for regulated unfolding of substrates, such as transcription factors ComK and ComS, and targeting them to ClpP for degradation. The six subunits of the MecA-ClpC complex form a closed barrel-like structure, featured with three stacked rings and a hollow passage, where substrates are threaded and translocated through successive pores. Although the general concepts of how polypeptides are unfolded and translocated by internal pore loops of AAA(+) proteins have long been conceived, the detailed mechanistic model remains elusive. With cryoelectron microscopy, we captured four different structures of the MecA-ClpC complexes. These complexes differ in the nucleotide binding states of the two AAA(+) rings and therefore might presumably reflect distinctive, representative snapshots from a dynamic unfolding cycle of this hexameric complex. Structural analysis reveals that nucleotide binding and hydrolysis modulate the hexameric complex in a number of ways, including the opening of the N-terminal ring, the axial and radial positions of pore loops, the compactness of the C-terminal ring, as well as the relative rotation between the two nucleotide-binding domain rings. More importantly, our structural and biochemical data indicate there is an active allosteric communication between the two AAA(+) rings and suggest that concerted actions of the two AAA(+) rings are required for the efficiency of the substrate unfolding and translocation. These findings provide important mechanistic insights into the dynamic cycle of the MecA-ClpC unfoldase and especially lay a foundation toward the complete understanding of the structural dynamics of the general type II AAA(+) hexamers.