RamaDA: complete and automated conformational overview of proteins

TL;DR

RamaDA is an automated tool that provides comprehensive conformational analysis of proteins by classifying backbone angles into domains, detecting secondary structures, irregularities, and characteristic patterns with high accuracy.

Contribution

It introduces a novel model decomposing the Ramachandran plot into seven domains, enabling detailed and automated conformational characterization of proteins.

Findings

Achieves secondary structure detection accuracy comparable to DSSP.

Detects PolyProline II structures and irregularities via z-scores.

Successfully identifies calcium-binding EF-hands with low false positives.

Abstract

The tertiary structure of protein, as well as the local secondary structure organization are fully determined by the angles of the peptidic bound. The backbone dihedral angles not only determine the global fold of the protein, but also the details of the local chain organization. Although a wealth of structural information is available in different databases and numerous structural biology softwares have been developed, rapid conformational characterization remains challenging. We present here RamaDA, a program able to give a synthetic description of the conformation of a protein. The RamaDA program is based on a model where the Ramachadran plot is decomposed into seven conformational domains. Within the framework of this model, each amino-acid of a given protein is assigned to one of these domains. From this assignment secondary structure elements can be detected with an accuracy equivalent to that of the DSSP program for helices and extended strands, and with the added capability of detecting PolyProline II secondary structures. Additionally, the determination of a z-score for each amino-acid of the protein emphasizes any irregularities in the element. It is also possible to use this analysis to detect characteristic conformational patterns. In the case of EF-hands, calcium-binding helix-loop-helix domains, it is possible to design a strict consensus for the 9 amino-acids of the loop. 523 calcium binding protein files can be found into the entire PDB with this pattern and only 2.7% false positive hits are detected. The program RamaDA gathers several tools in one and is then able to give a complete information on a protein structure, including loops and random coil regions. Through the example of EF-hands, a promising approach of structural biology is developed. RamaDA is freely available for download as well as online usage at http://ramada.u-strasbg.fr