CONICET | Buscador de Institutos y Recursos Humanos

Background The notion of energy landscapes provides conceptual tools for understanding the complexities of protein folding and function. Energy Landscape Theory indicates that it is much easier to find sequences that satisfy the ?Principle of Minimal Frustration?´ when the folded structure is symmetric. Similarly, repeats and structural mosaics may be fundamentally related to landscapes with multiple embedded funnels. The mere existence of repetitions does not guarantee that the system will be symmetric as these should arrange in particular ways and coalesce into higher order patterns. Detecting repeated units and patterns is a first step towards an understanding of their assembly in complete structures and the emergence of symmetry. Description: We present analytical tools to detect and compare structural repetitions in protein molecules. By an exhaustive analysis of the distribution of structural repeats using a robust metric we define those portions of a protein molecule that best describe the overall structure as tessellation of basic units. Patterns produced by such tessellations provide intuitive representations of the repeating regions and their association towards higher order arrangements. Conclusion: We developed concepts and methods to structurally compare repetitions and patterns in protein structures. We find that some protein architectures can be described as nearly periodic, while in others clear separations between repetitions exist. Since the method is independent of amino acid sequence information we can identify structural units that can be encoded with different primary elements. The methods can be applied to various topological families and resolve fine geometrical differences. Moreover, we define a metric that allows for a crude comparison of the symmetrical dispositions of repetitions between proteins of different size, topology and quaternary arrangement on the same grounds.