Hsp70 biases the folding pathways of client proteins

Ashok Sekhar, Rina Rosenzweig, Guillaume Bouvignies, Lewis E. Kay, Arnold Raitsimring, Gottfried Otting, Bim Graham

Research output: Contribution to journalArticlepeer-review

Abstract

The 70-kDa heat shock protein (Hsp70) family of chaperones bind cognate substrates to perform a variety of different processes that are integral to cellular homeostasis. Although detailed structural information is available on the chaperone, the structural features of folding competent substrates in the bound form have not been well characterized. Here we use paramagnetic relaxation enhancement (PRE) NMR spectroscopy to probe the existence of long-range interactions in one such folding competent substrate, human telomere repeat binding factor (hTRF1), which is bound to DnaK in a globally unfolded conformation. We show that DnaK binding modifies the energy landscape of the substrate by removing long-range interactions that are otherwise present in the unbound, unfolded conformation of hTRF1. Because the unfolded state of hTRF1 is only marginally populated and transiently formed, it is inaccessible to standard NMR approaches. We therefore developed a 1H-based CEST experiment that allows measurement of PREs in sparse states, reporting on transiently sampled conformations. Our results suggest that DnaK binding can significantly bias the folding pathway of client substrates such that secondary structure forms first, followed by the development of longer-range contacts between more distal parts of the protein.

Original languageEnglish
Pages (from-to)E2794-2801
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number20
DOIs
StatePublished - 17 May 2016

All Science Journal Classification (ASJC) codes

  • General

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