RT Journal Article
SR Electronic
T1 The Folding Pathway of an Ig Domain is Conserved On and Off the Ribosome
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 253013
DO 10.1101/253013
A1 Tian, Pengfei
A1 Steward, Annette
A1 Kudva, Renuka
A1 Su, Ting
A1 Shilling, Patrick J.
A1 Nickson, Adrian A.
A1 Hollins, Jeffrey J.
A1 Beckmann, Roland
A1 Von Heijne, Gunnar
A1 Best, Robert B.
A1 Clarke, Jane
YR 2018
UL http://biorxiv.org/content/early/2018/01/24/253013.abstract
AB Proteins that fold cotranslationally do so in a restricted configurational space, due to the volume occupied by the ribosome. Here, we investigate the cotranslational folding of an all-β immunoglobulin domain, titin I27, whose intrinsic folding mechanism has been extensively characterized. Using an arrest peptide-based assay and structural studies by cryo-EM, we show that I27 folds in the mouth of the ribosome exit tunnel. Simulations that use a kinetic model for the force-dependence of escape from arrest, accurately predict the fraction of folded protein as a function of length. We used these simulations to probe the folding pathway on and off the ribosome. Our simulations - which also reproduce experiments on mutant forms of I27 - show that I27 folds, while still sequestered in the ribosome, by essentially the same pathway as free I27, with only subtle shifts of critical contacts from the C to the N terminus.