Abstract:
:An increasing number of protein structures are found to encompass multiple folding nuclei, allowing their structures to be formed by several competing pathways. A typical example is the ribosomal protein S6, which comprises two folding nuclei (sigma1 and sigma2) defining two competing pathways in the folding energy landscape: sigma1 --> sigma2 and sigma2 --> sigma1. The balance between the two pathways, and thus the order of folding events, is easily controlled by circular permutation. In this study, we make use of this ability to manipulate the folding pathway to demonstrate that the dynamic motions of the S6 structure are independent of how the protein folds. The HD-exchange protection factors remain the same upon complete reversal of the folding order. The phenomenon arises because the HD-exchange motions and the high-energy excitations controlling the folding pathway occur at separated free-energy levels: the Boltzmann distribution of unproductive unfolding attempts samples all unfolding channels in parallel, even those that end up in excessively high barriers. Accordingly, the findings provide a simple rationale for how to interpret native-state dynamics without the need to invoke fluctuations off the normal unfolding reaction coordinate.
journal_name
Proc Natl Acad Sci U S Aauthors
Haglund E,Lind J,Oman T,Ohman A,Mäler L,Oliveberg Mdoi
10.1073/pnas.0907665106subject
Has Abstractpub_date
2009-12-22 00:00:00pages
21619-24issue
51eissn
0027-8424issn
1091-6490pii
0907665106journal_volume
106pub_type
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