ИСТИНА

NMR spectroscopy is an effective tool for studying protein structure and dynamics and searching of low molecular weight compounds capable to bind specifically to the target protein, altering its functional properties towards the desired therapeutic effect. In progress of ongoing NMR studies of pharmacologically important proteins, we started investigating new promising drug targets - N-terminal domain of telomerase catalytic subunit (TEN) and methyltransferase WBSCR27, associated with the Williams syndrome. Both proteins were discovered, expressed and purified by the colleagues from the A.N. Belozersky Institute of Physico-Chemical Biology (Moscow University). Telomerase is a ribonucleoprotein complex responsible for the maintenance of telomeres - special structural fragments at the end of liner eukaryotic chromosomes specialized to protect them and keep their integrity. This enzyme is the focus of substantial attention, both because its structure and mechanism of action are still poorly studied, and because of its pivotal roles in aging and cellular proliferation. The use of telomerase as a potential target for the design of new anticancer drugs is also of great interest. However, to date, there is no example of the successful creation of a telomerase inhibitor using the rational design methods due to the limited structural information about this ribonucleoprotein complex. The catalytic protein subunit of telomerase (TERT) contains an N-terminal domain (TEN) that is essential for activity and processivity. Elucidation of the structure and dynamics of TEN in solution is important for understanding the molecular mechanism of telomerase activity and for the design of new telomerase inhibitors. To approach this problem, we obtained the 1H, 13C, and 15N chemical shift assignments of TEN from Ogataea polymorpha (159 amino acids, 18.6 кДа) and determined high-resolution structure of this protein in solution. All multidimensional heteronuclear NMR experiments were acquired at the NMR facilities of Institute of Physics, Kazan Federal University. Second protein is a novel methyltransferase WBSCR27 from the Mus musculus (27 kDa, 240 a.a.). This is the product of a gene associated with the genetic disease -Williams syndrome. No structural information is available for this protein, and only little is known about its function. Series of high-field (19.8 T, 850 MHz) 3D heteronuclear NMR spectra were acquired for WBSCR27 using NMR spectrometers of the High-Field Nuclear Magnetic Resonance, Institute of Biomedical Sciences, Academia Sinica, Taiwan. NMR spectra indicates that WBSCR27 protein exists in two conformational states, which substantially complicates data analysis. However, about 70% of all the non-proline backbone 1H, 13C, and 15N resonances were assigned up to date using a set of 3D TROSY-based NMR experiments. Assigned chemical shifts were used to determine the secondary structure of WBSCR27 and to reveal the rigid core of the protein and the flexible unstructured loops. Obtained data will subsequently be used to determine solution structure of the protein, which is important in understanding of the mechanism of action of the enzyme and elucidation of the molecular basis of the Williams syndrome genetic disease.