Format

Send to

Choose Destination
Nat Struct Mol Biol. 2014 Oct;21(10):871-5. doi: 10.1038/nsmb.2885. Epub 2014 Sep 7.

Mechanochemical basis of protein degradation by a double-ring AAA+ machine.

Author information

1
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
2
1] Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. [2].
3
1] Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. [2] Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.

Abstract

Molecular machines containing double or single AAA+ rings power energy-dependent protein degradation and other critical cellular processes, including disaggregation and remodeling of macromolecular complexes. How the mechanical activities of double-ring and single-ring AAA+ enzymes differ is unknown. Using single-molecule optical trapping, we determine how the double-ring ClpA enzyme from Escherichia coli, in complex with the ClpP peptidase, mechanically degrades proteins. We demonstrate that ClpA unfolds some protein substrates substantially faster than does the single-ring ClpX enzyme, which also degrades substrates in collaboration with ClpP. We find that ClpA is a slower polypeptide translocase and that it moves in physical steps that are smaller and more regular than steps taken by ClpX. These direct measurements of protein unfolding and translocation define the core mechanochemical behavior of a double-ring AAA+ machine and provide insight into the degradation of proteins that unfold via metastable intermediates.

PMID:
25195048
PMCID:
PMC4190165
DOI:
10.1038/nsmb.2885
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Nature Publishing Group Icon for PubMed Central
Loading ...
Support Center