3KTT

Atomic model of bovine TRiC CCT2(beta) subunit derived from a 4.0 Angstrom cryo-EM map

3KTT の概要

• エントリーDOI: 10.2210/pdb3ktt/pdb
• 関連するPDBエントリー: 3IYG
• EMDBエントリー: 5145 5148
• 分子名称: T-complex protein 1 subunit beta (1 entity in total)
• 機能のキーワード: tric/cct, cct2(beta), cryo-em, acetylation, atp-binding, chaperone, cytoplasm, nucleotide-binding
• 由来する生物種: Bos taurus (bovine)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 55107.23

構造登録者

Cong, Y.,Baker, M.L.,Ludtke, S.J.,Frydman, J.,Chiu, W. (登録日: 2009-11-25, 公開日: 2010-03-16, 最終更新日: 2024-02-21)

主引用文献

Cong, Y.,Baker, M.L.,Jakana, J.,Woolford, D.,Miller, E.J.,Reissmann, S.,Kumar, R.N.,Redding-Johanson, A.M.,Batth, T.S.,Mukhopadhyay, A.,Ludtke, S.J.,Frydman, J.,Chiu, W.
4.0-A resolution cryo-EM structure of the mammalian chaperonin TRiC/CCT reveals its unique subunit arrangement.
Proc.Natl.Acad.Sci.USA, 107:4967-4972, 2010

PubMed Abstract: The essential double-ring eukaryotic chaperonin TRiC/CCT (TCP1-ring complex or chaperonin containing TCP1) assists the folding of approximately 5-10% of the cellular proteome. Many TRiC substrates cannot be folded by other chaperonins from prokaryotes or archaea. These unique folding properties are likely linked to TRiC's unique heterooligomeric subunit organization, whereby each ring consists of eight different paralogous subunits in an arrangement that remains uncertain. Using single particle cryo-EM without imposing symmetry, we determined the mammalian TRiC structure at 4.7-A resolution. This revealed the existence of a 2-fold axis between its two rings resulting in two homotypic subunit interactions across the rings. A subsequent 2-fold symmetrized map yielded a 4.0-A resolution structure that evinces the densities of a large fraction of side chains, loops, and insertions. These features permitted unambiguous identification of all eight individual subunits, despite their sequence similarity. Independent biochemical near-neighbor analysis supports our cryo-EM derived TRiC subunit arrangement. We obtained a Calpha backbone model for each subunit from an initial homology model refined against the cryo-EM density. A subsequently optimized atomic model for a subunit showed approximately 95% of the main chain dihedral angles in the allowable regions of the Ramachandran plot. The determination of the TRiC subunit arrangement opens the way to understand its unique function and mechanism. In particular, an unevenly distributed positively charged wall lining the closed folding chamber of TRiC differs strikingly from that of prokaryotic and archaeal chaperonins. These interior surface chemical properties likely play an important role in TRiC's cellular substrate specificity.

PubMed: 20194787
DOI: 10.1073/pnas.0913774107

実験手法

ELECTRON MICROSCOPY (4 Å)