Ras proteins are small G proteins playing a major role in eukaryotic signal transduction. Guanine nucleotide exchange factors (GEF) stimulate GDP/GTP exchange, resulting in the formation of the active Ras-GTP complex. In mammalian cells, two major Ras-specific GEF exist: Sos-like and Cdc25-like. To date, structural data are available only for Cdc25(Mm). We designed and synthesized Cdc25(Mm)-derived peptides spanning residues corresponding to the hSos1 HI helical hairpin that has been implicated in the GEF catalytic mechanism. NMR experiments on a chemically synthesized Cdc25(1178-1222)(Mm) peptide proved that helix I readily reaches a conformation very similar to the corresponding helix in hSos 1, while residues corresponding to helix H in hSos1 show higher conformational flexibility. Molecular dynamics studies with the appropriate solvent model showed that different conformational spaces are available for the peptide. Since helix H is making several contacts with Ras and a Cdc25(1178-1222)(Mm) peptide is able to bind nucleotide-free Ras in a BIAcore assay, the peptide must be able to obtain the proper Ras-interacting conformation, at least transiently. These results indicate that rational design and improvement of the Ras-interacting peptides should take into account conformational and flexibility features to obtain molecules with the appropriate biochemical properties.
|Citazione:||Consonni, R., Arosio, I., Recca, T., Longhi, R., Colombo, G., & Vanoni, M.E. (2003). Structure determination and dynamics of peptides overlapping the catalytic hairpin of the Ras-specific GEF Cdc25(Mm). BIOCHEMISTRY, 42(42), 12154-12162.|
|Tipo:||Articolo in rivista - Articolo scientifico|
|Carattere della pubblicazione:||Scientifica|
|Titolo:||Structure determination and dynamics of peptides overlapping the catalytic hairpin of the Ras-specific GEF Cdc25(Mm)|
|Autori:||Consonni, R; Arosio, I; Recca, T; Longhi, R; Colombo, G; Vanoni, ME|
|Data di pubblicazione:||28-ott-2003|
|Appare nelle tipologie:||01 - Articolo su rivista|