Cryo-EM reveals an asymmetry in a novel single-ring viral chaperonin.
J Struct Biol
; 209(2): 107439, 2020 02 01.
Article
in En
| MEDLINE
| ID: mdl-31870903
ABSTRACT
Chaperonins are ubiquitously present protein complexes, which assist the proper folding of newly synthesized proteins and prevent aggregation of denatured proteins in an ATP-dependent manner. They are classified into group I (bacterial, mitochondrial, chloroplast chaperonins) and group II (archaeal and eukaryotic cytosolic variants). However, both of these groups do not include recently discovered viral chaperonins. Here, we solved the symmetry-free cryo-EM structures of a single-ring chaperonin encoded by the gene 246 of bacteriophage OBP Pseudomonas fluorescens, in the nucleotide-free, ATPγS-, and ADP-bound states, with resolutions of 4.3 Å, 5.0 Å, and 6 Å, respectively. The structure of OBP chaperonin reveals a unique subunit arrangement, with three pairs of subunits and one unpaired subunit. Each pair combines subunits in two possible conformations, differing in nucleotide-binding affinity. The binding of nucleotides results in the increase of subunits' conformational variability. Due to its unique structural and functional features, OBP chaperonin can represent a new group.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Chaperonins
/
Chaperonin 60
/
Cryoelectron Microscopy
Language:
En
Journal:
J Struct Biol
Journal subject:
BIOLOGIA MOLECULAR
Year:
2020
Document type:
Article
Affiliation country:
RUSSIA