TY - JOUR
T1 - The cotranslational contacts between ribosome-bound nascent polypeptides and the subunits of the hetero-oligomeric chaperonin TRiC probed by photocross-linking
AU - Etchells, Stephanie A.
AU - Meyer, Anne S.
AU - Yam, Alice Y.
AU - Roobol, Anne
AU - Miao, Yiwei
AU - Shao, Yuanlong
AU - Carden, Martin J.
AU - Skach, William R.
AU - Frydman, Judith
AU - Johnson, Arthur E.
PY - 2005/7/29
Y1 - 2005/7/29
N2 - The hetero-oligomeric eukaryotic chaperonin TRiC (TCP-1-ring complex, also called CCT) interacts cotranslationally with a diverse subset of newly synthesized proteins, including actin, tubulin, and luciferase, and facilitates their correct folding. A photocross-linking approach has been used to map the contacts between individual chaperonin subunits and ribosome-bound nascent chains of increasing length. Whereas a cryo-EM study suggests that chemically denatured actin interacts with only two TRiC subunits (δ and either β or ε), actin and luciferase chains photocross-link to at least six TRiC subunits (α, β, δ, ε, ξ, and θ) at different stages of translation. Furthermore, the photocross-linking of actin, but not luciferase, nascent chains to TRiC sub-units ζ and θ was length-dependent. In addition, a single photoreactive probe incorporated at a unique site in actin nascent chains of different lengths reacted covalently with multiple TRiC subunits, thereby indicating that the nascent chain samples the polypeptide binding sites of different subunits. We conclude that elongating actin and luciferase nascent chains contact multiple TRiC subunits upon emerging from the ribosome, and that the TRiC subunits contacted by nascent actin change as it elongates and starts to fold.
AB - The hetero-oligomeric eukaryotic chaperonin TRiC (TCP-1-ring complex, also called CCT) interacts cotranslationally with a diverse subset of newly synthesized proteins, including actin, tubulin, and luciferase, and facilitates their correct folding. A photocross-linking approach has been used to map the contacts between individual chaperonin subunits and ribosome-bound nascent chains of increasing length. Whereas a cryo-EM study suggests that chemically denatured actin interacts with only two TRiC subunits (δ and either β or ε), actin and luciferase chains photocross-link to at least six TRiC subunits (α, β, δ, ε, ξ, and θ) at different stages of translation. Furthermore, the photocross-linking of actin, but not luciferase, nascent chains to TRiC sub-units ζ and θ was length-dependent. In addition, a single photoreactive probe incorporated at a unique site in actin nascent chains of different lengths reacted covalently with multiple TRiC subunits, thereby indicating that the nascent chain samples the polypeptide binding sites of different subunits. We conclude that elongating actin and luciferase nascent chains contact multiple TRiC subunits upon emerging from the ribosome, and that the TRiC subunits contacted by nascent actin change as it elongates and starts to fold.
UR - http://www.scopus.com/inward/record.url?scp=23044445800&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=23044445800&partnerID=8YFLogxK
U2 - 10.1074/jbc.M504110200
DO - 10.1074/jbc.M504110200
M3 - Article
C2 - 15929940
AN - SCOPUS:23044445800
SN - 0021-9258
VL - 280
SP - 28118
EP - 28126
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 30
ER -