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| Title | Structural dynamics of the MecA-ClpC complex: a type II AAA+ protein unfolding machine. |
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| Journal, issue, pages | J Biol Chem, Vol. 288, Issue 24, Page 17597-17608, Year 2013 |
| Publish date | Jun 14, 2013 |
 Authors | Jing Liu / Ziqing Mei / Ningning Li / Yutao Qi / Yanji Xu / Yigong Shi / Feng Wang / Jianlin Lei / Ning Gao /  |
| 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 ...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. |
 External links | J Biol Chem / PubMed:23595989 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 9.0 - 11.0 Å |
| Structure data | EMDB-5607: Structural dynamics and inter-ring communication of the MecA-ClpC complex during active substrate unfolding and translocation revealed by cryo-EM EMDB-5608: Structural dynamics and inter-ring communication of the MecA-ClpC protease complex during active substrate unfolding and translocation revealed by cryo-EM |
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 Keywords |  CHAPERONE / ClpC / MecA / AAA+ ATPase / PROTEIN unfolding |
