Formulation of probabilistic models of protein structure in atomic detail using the reference ratio method.
We propose a method to formulate probabilistic models of protein structure in atomic detail, for a given amino acid sequence, based on Bayesian principles, while retaining a close link to physics. We start from two previously developed probabilistic models of protein structure on a local length scale, which concern the dihedral angles in main chain and side chains, respectively. Conceptually, this constitutes a probabilistic and continuous alternative to the use of discrete fragment and rotamer libraries. The local model is combined with a nonlocal model that involves a small number of energy terms according to a physical force field, and some information on the overall secondary structure content. In this initial study we focus on the formulation of the joint model and the evaluation of the use of an energy vector as a descriptor of a protein's nonlocal structure; hence, we derive the parameters of the nonlocal model from the native structure without loss of generality. The local and nonlocal models are combined using the reference ratio method, which is a well-justified probabilistic construction. For evaluation, we use the resulting joint models to predict the structure of four proteins. The results indicate that the proposed method and the probabilistic models show considerable promise for probabilistic protein structure prediction and related applications.
The Bioinformatics Centre, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Jan B
JB
Valentin
Christian
C
Andreetta
Wouter
W
Boomsma
Sandro
S
Bottaro
Jesper
J
Ferkinghoff-Borg
Jes
J
Frellsen
Kanti V
KV
Mardia
Pengfei
P
Tian
Thomas
T
Hamelryck
D000465:Algorithms; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D001499:Bayes Theorem; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015233:Models, Statistical; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D040681:Structural Homology, Protein; D013816:Thermodynamics
D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus
Bayesian models; disordered proteins; protein structure prediction; reference ratio method; template-free modeling