title: 2.8 Å resolution reconstruction of the Thermoplasma acidophilum 20S proteasome using cryo-electron microscopy.
abstract: Recent developments in detector hardware and image-processing software have revolutionized single particle cryo-electron microscopy (cryoEM) and led to a wave of near-atomic resolution (typically ∼3.3 Å) reconstructions. Reaching resolutions higher than 3 Å is a prerequisite for structure-based drug design and for cryoEM to become widely interesting to pharmaceutical industries. We report here the structure of the 700 kDa Thermoplasma acidophilum 20S proteasome (T20S), determined at 2.8 Å resolution by single-particle cryoEM. The quality of the reconstruction enables identifying the rotameric conformation adopted by some amino-acid side chains (rotamers) and resolving ordered water molecules, in agreement with the expectations for crystal structures at similar resolutions. The results described in this manuscript demonstrate that single particle cryoEM is capable of competing with X-ray crystallography for determination of protein structures of suitable quality for rational drug design.
authors.affiliation: National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, United States.
authors.forename: Melody G
authors.initials: MG
authors.lastname: Campbell
authors.affiliation: National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, United States.
authors.forename: David
authors.initials: D
authors.lastname: Veesler
authors.affiliation: National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, United States.
authors.forename: Anchi
authors.initials: A
authors.lastname: Cheng
authors.affiliation: National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, United States.
authors.forename: Clinton S
authors.initials: CS
authors.lastname: Potter
authors.affiliation: National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, United States.
authors.forename: Bridget
authors.initials: B
authors.lastname: Carragher
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy / Q000379:methods*; D018360:Crystallography, X-Ray; D021621:Imaging, Three-Dimensional; D008958:Models, Molecular; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000648:ultrastructure*; D011487:Protein Conformation; D015203:Reproducibility of Results; D013822:Thermoplasma / Q000378:metabolism*
chemical_list: D019843:Archaeal Proteins; D046988:Proteasome Endopeptidase Complex
keywords: T. acidophilum; biophysics; direct detectors; electron microscopy; image processing; structural biology