Zooming into the overall architecture of the giant muscle protein titin

Abstract

The giant muscle protein titin extends over one half of the muscle sarcomere. In its largest isoform titin comprises more than 38,000 residues and about 300 domains. Its structural complexity does not allow the application of classical structural biology methods to determine its overall architecture. Therefore, we have decided to chop the protein into smaller fragments and determine the high resolution structures of representative parts. Within this endeavor, we have also become interested to consider known ligands involved in the titin interactome for structural/functional analysis. Over the last decade, we determined structures of the N-terminal assembly complex (Zou et al., 2006), from the I-band (Mayans et al., 2001; Vega et al., unpublished) and from the A-band including the kinase domain and down-stream signaling complexes (Mayans et al., 1998; Muller et al., 2006; Muller et al., 2007; Muller et al., unpublished; Chen et al., unpublished). The available data allow modeling a large part of the titin proteome and to interpret available low resolution data of the entire titin filament. Combined with complementary functional data, our findings reveal key structural/functional relationships of titin and its interactions partners. Structural biology results from a related sarcomeric filament protein, myomesin (also known as mini-titin) will be presented in a separate contribution. Some of the data have been published recently