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Many proteins and protein regions have been shown to be intrinsically disordered in their native conformations. Comparative analyses suggest that they are predominantly located in the nucleus and involved in transcription regulation, cell signaling, cell cycle control, replication and biogenesis of cytoskeleton. Disorder plays an important role in protein-protein interactions and it has been suggested that it favours multiple-partner binding and high-specificity/low-affinity binding. It has also been shown to increase with organism complexity.
Centrosome is a dynamic complex involved in several regulatory functions, including cell cycle transitions, cellular responses to stress, and organization of signal transduction pathways. Centrosomal proteins tend to be long, disordered and coiled coil. Is the disorder found in the centrosomal proteome important for regulation? Is it driven by the need of structural plasticity of this highly complex molecular machine? To address these questions, we have adopted an evolutionary perspective, comparing different structural and functional aspects of the centrosomal proteins, including disorder, coiled-coil structure and phosphorilation among 6 different model species. We show that long, disordered segments are found in a larger proportion of centrosomal proteins than in generic proteins of the same species, and that this trend is observed also in the proportion of disordered residues. The coiled-coil frequency follows a parallel behaviour, giving a hint on the functional relationship among them. We find also that relative phosphorylation is significantly correlated with disorder. Either a functional or neutral interpretation are possible and not mutually exclusive. While disordered and coiled coil fragments are more likely to arise in evolution, these observed features might be enhancing the plasticity of the centrosome and its complex regulation in space and time. |
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