SPRITE

SPRITE searches PDB-format query protein structures against a database of three-dimensional amino acid side-chain arrangements using graph-theoretical representations of pseudo-atoms to identify functional 3D motifs and sites.

Key Features:

• PDB Query Input: Accepts query protein structures in PDB format for motif searches.
• Database Comparison: Compares queries against a database of 3D side-chain arrangements focused on sites and motifs.
• Graph-Theoretical Representation: Represents side-chain geometry within a graph-theoretical framework.
• Pseudo-atom Encoding: Encodes amino acid side chains as pseudo-atoms that serve as labeled graph nodes.
• Distance-Encoded Edges: Uses edges corresponding to inter-pseudo-atomic distances to capture geometric relationships.
• Sequence/Fold-Independent Detection: Identifies similarities in three-dimensional side-chain patterns even when sequence or fold similarities are not detectable.
• Functional Match Identification: Finds matches between query side-chain patterns and database entries with characterized functions to suggest potential functional motifs and sites.

Scientific Applications:

• Functional Motif Identification: Detects functional 3D side-chain motifs and sites within proteins.
• Functional Annotation via Structural Analogs: Aids annotation of protein function by locating structural analogs of characterized functional sites.
• Structural Bioinformatics Investigations: Supports studies of protein function and interactions based on side-chain geometric patterns.

Methodology:

SPRITE represents amino acid side chains as pseudo-atoms, constructs labeled graphs with pseudo-atoms as nodes and edges defined by inter-pseudo-atomic distances, and compares geometric relationships of side-chain patterns across structures and against a database of 3D side-chain arrangements using graph-theoretical methods.