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Analysis of multiple folding routes of proteins by a coarse-grained dynamics model.

ABSTRACT: Langevin dynamics of a protein molecule with Go-type potentials is developed and used to analyze long time-scale events in the folding of cytochrome c. Several trajectories are generated, starting from random coil configurations and going to the native state, that are a few angstroms root mean square deviation (RMSD) from the native structure. The dynamics is controlled, to a large scale, by the two terminal helices that are in contact in the native state. These two helices form very early during folding, and depending on the trajectory, they either stabilize rapidly or break and re-form in going over steric barriers. The extended initial chain exhibits a rapid folding transition into a relatively compact shape, after which the helices are reorganized in a highly correlated manner. The time of formation of residue pair contacts strongly points to the hierarchical nature of folding; i.e., secondary structure forms first, followed by rearrangements of larger length scales at longer times. The kinetics of formation of native contacts is also analyzed, and the onset of a stable globular configuration, referred to as the molten globule in the literature, is identified. Predictions of the model are compared with extensive experimental data on cytochrome c.

SUBMITTER: Erman B

PROVIDER: S-EPMC1301808 | biostudies-other | 2001 Dec

REPOSITORIES: biostudies-other

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Analysis of multiple folding routes of proteins by a coarse-grained dynamics model.

Erman B B

Biophysical journal 20011201 6

Langevin dynamics of a protein molecule with Go-type potentials is developed and used to analyze long time-scale events in the folding of cytochrome c. Several trajectories are generated, starting from random coil configurations and going to the native state, that are a few angstroms root mean square deviation (RMSD) from the native structure. The dynamics is controlled, to a large scale, by the two terminal helices that are in contact in the native state. These two helices form very early durin ...[more]

PMID: 11721014

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Project description:Coarse-grained molecular dynamics simulations offer a dramatic extension of the time-scale of simulations compared to all-atom approaches. In this article, we describe the use of the physics-based united-residue (UNRES) force field, developed in our laboratory, in protein-structure simulations. We demonstrate that this force field offers about a 4000-times extension of the simulation time scale; this feature arises both from averaging out the fast-moving degrees of freedom and reduction of the cost of energy and force calculations compared to all-atom approaches with explicit solvent. With massively parallel computers, microsecond folding simulation times of proteins containing about 1000 residues can be obtained in days. A straightforward application of canonical UNRES/MD simulations, demonstrated with the example of the N-terminal part of the B-domain of staphylococcal protein A (PDB code: 1BDD, a three-alpha-helix bundle), discerns the folding mechanism and determines kinetic parameters by parallel simulations of several hundred or more trajectories. Use of generalized-ensemble techniques, of which the multiplexed replica exchange method proved to be the most effective, enables us to compute thermodynamics of folding and carry out fully physics-based prediction of protein structure, in which the predicted structure is determined as a mean over the most populated ensemble below the folding-transition temperature. By using principal component analysis of the UNRES folding trajectories of the formin-binding protein WW domain (PDB code: 1E0L; a three-stranded antiparallel beta-sheet) and 1BDD, we identified representative structures along the folding pathways and demonstrated that only a few (low-indexed) principal components can capture the main structural features of a protein-folding trajectory; the potentials of mean force calculated along these essential modes exhibit multiple minima, as opposed to those along the remaining modes that are unimodal. In addition, a comparison between the structures that are representative of the minima in the free-energy profile along the essential collective coordinates of protein folding (computed by principal component analysis) and the free-energy profile projected along the virtual-bond dihedral angles gamma of the backbone revealed the key residues involved in the transitions between the different basins of the folding free-energy profile, in agreement with existing experimental data for 1E0L .

Dataset Information

Analysis of multiple folding routes of proteins by a coarse-grained dynamics model.

Publications

Analysis of multiple folding routes of proteins by a coarse-grained dynamics model.

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