[Chimeric SHA-D domain ("SH3-Bergerac"): 3D-structure and dynamics studies in solution].

Protein SHA-D of "SH3-Bergerac" chimeric proteins family was constructed by substitution of beta-turn N47-D48 in spectrin SH3-domain by KATANDKTYE amino acid sequence. Structural and dynamics properties of SHA-D in solution were studied by with the help of high-resolution NMR. The extension of SHA-D polypeptide chain in comparison with wild type of protein WT-SH3 (~ 17%) practically doesn't affect almost the total molecule topology. 3D-structure of SHA-D is practically identical to the proteins of "SH3-Bergerac" family. However there are some differences in dynamic characteristics in the region of substitution. The G52D substitution in SHA-D protein results in a destabilization of the region insertion where the conditions for conformational exchange appear. Destabilization further affects the entire SHA- D molecule making its structure more labile.

[NMR structure and dynamics of the chimeric protein SH3-F2].

For the further elucidation of structural and dynamic principles of protein self-organization and protein-ligand interactions the design of new chimeric protein SH3-F2 was made and genetically engineered construct was created. The SH3-F2 amino acid sequence consists of polyproline ligand mgAPPLPPYSA, GG linker and the sequence of spectrin SH3 domain circular permutant S19-P20s. Structural and dynamics properties of the protein were studied by high-resolution NMR. According to NMR data the tertiary structure of the chimeric protein SH3-F2 has the topology which is typical of SH3 domains in the complex with the ligand, forming polyproline type II helix, located in the conservative region of binding in the orientation II. The polyproline ligand closely adjoins with the protein globule and is stabilized by hydrophobic interactions. However the interaction of ligand and the part of globule relative to SH3 domain is not too large because the analysis of protein dynamic characteristics points to the low amplitude, high-frequency ligand tumbling in relation to the slow intramolecular motions of the main globule. The constructed chimera permits to carry out further structural and thermodynamic investigations of polyproline helix properties and its interaction with regulatory domains.

[Study of the structure and dynamics of a chimeric variant of the SH3 domain (SHA-Bergerac) by NMR spectroscopy].

A structural-dynamic study of one of the chimeric proteins (SHA) belonging to the SH3-Bergerac family and containing the KATANGKTYE sequence instead of the N47D48 beta-turn in the spectrin SH3 domain was carried out by high resolution NMR spectroscopy. The spatial structure of the protein was determined and its dynamics in solution was investigated on the basis of the NMR data. The elongation of the SHA polypeptide chain in comparison with the WT-SH3 original protein (by ~17%) exerts practically no effect on the general topology of the molecule. The presence of a stable beta-hairpin in the region of insertion was confirmed. This hairpin was shown to have a higher mobility in comparison with other regions of the protein.