Rosetta Fold Tree: A Data Structure for Protein Folding Path Representation

Rosetta's fold tree is a data structure that represents the folding path of a protein. It describes the protein's topology during folding, specifically the connectivity and spatial arrangement of its amino acid residues. The fold tree is widely used in Rosetta for simulating protein folding processes and performing structure prediction.

The basic unit of a fold tree is a node, each representing an amino acid residue in the protein. Each node stores the coordinates of the residue and the connection type with its neighboring residues. Nodes are connected by edges, representing chemical bonds between adjacent residues. Fold tree edges come in two types: main chain and side chain. Main chain edges connect two consecutive Cα atoms, while side chain edges connect two consecutive side chain atoms.

Fold trees can represent the natural folding path of proteins, but also simulate folding under different conditions. By adjusting the connectivity between nodes in the fold tree, it's possible to model folding under various environments, enabling predictions of potential structures.