 |
PDBsum entry 3j3s
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
|
(+ 0 more)
94 a.a.
|
|
|
|
|
|
|
|
|
|
|
(+ 0 more)
798 a.a.
|
|
|
|
|
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Structural dynamics of the meca-Clpc complex: a type ii aaa+ protein unfolding machine.
|
|
|
Authors
|
|
J.Liu,
Z.Mei,
N.Li,
Y.Qi,
Y.Xu,
Y.Shi,
F.Wang,
J.Lei,
N.Gao.
|
|
|
Ref.
|
|
J Biol Chem, 2013,
288,
17597-17608.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
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.
|
|
|
|
|
|
|
