3J3R
Structural dynamics of the MecA-ClpC complex revealed by cryo-EM
Summary for 3J3R
| Entry DOI | 10.2210/pdb3j3r/pdb |
| Related | 3J3S 3J3T 3J3U |
| EMDB information | 5610 |
| Descriptor | Adapter protein MecA 1, Negative regulator of genetic competence ClpC/MecB (2 entities in total) |
| Functional Keywords | clpc, meca, aaa+ atpase, protein unfolding, chaperone |
| Biological source | Bacillus subtilis More |
| Total number of polymer chains | 12 |
| Total formula weight | 695563.59 |
| Authors | |
| Primary citation | Liu, J.,Mei, Z.,Li, N.,Qi, Y.,Xu, Y.,Shi, Y.,Wang, F.,Lei, J.,Gao, N. Structural dynamics of the MecA-ClpC complex: a type II AAA+ protein unfolding machine J.Biol.Chem., 288:17597-17608, 2013 Cited by PubMed 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. PubMed: 23595989DOI: 10.1074/jbc.M113.458752 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (9.4 Å) |
Structure validation
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