Secondary Structure Of N-terminal Domain Research Articles

Changes in Secondary Structure of Human Prion Protein Peptide 30-90 under the Influence of Selected Dicationic and Anionic Surfactants

The peptide (PrP30-90), which was used in this study, was designed on the basis of amino acid sequence of the unstructured N-terminal domain of human prion protein. Flexibility of this moiety and physicochemical properties of PrP N-terminal domain are related to the ability of prion protein to bind metal cations and are probably linked with the pathological conformational changes and formation insoluble deposits of this protein in the brain, which were observed in transmissible spongiform encephalopathies (e.g. Creutzfeldt-Jakob disease, CJD) [1]. This peptide, as well as N-terminal domain of PrP, possesses octarepeat sequences containing four histidine residues which overlap with binding sites of metal ions (copper, zinc etc). Interactions with surfactants probably could influence secondary structure of N-terminal domain or even full human prion protein. The present study was aimed at determination of the effects of cationic gemini imidazolium surfactant and anionic surfactant with different spacer groups on secondary structure of human prion protein at different pH values. The studies were carried out in MES buffer (pH 5.5) and phosphate buffer (pH 7,4) using circular dichroism (CD, Fourier transform infrared spectroscopy (FTIR) spectroscopy, NMR diffusometry and transmission electron microscopy (TEM). This work was supported by the funds from the National Science Centre (Poland) granted on the basis of decision no. 2016/23/N/ST5/02013. [1] Cobb N.J., Surewicz W.K. (2009) Biochemistry. 48(12), 2574-2585.

Effects of the N-terminal and C-terminal domains of Meiothermus ruber CBS-01 trehalose synthase on thermostability and activity

Numerous trehalose synthases (TreS) from thermophilic microorganisms have extra C-terminal domains. To determine the function of the N- and C-terminal domains of TreS from the thermophilic bacterium Meiothermus ruber CBS-01, the two domains were expressed. From the findings, the N-terminal domain from M. ruber was not active when compared with that from Thermus thermophilus, which had been studied previously. The circular dichroism spectrum showed that the secondary structure of N-terminal domain from M. ruber underwent a greater change than that of C terminus. In addition, the N-terminal domain from T. thermophilus and C terminus from M. ruber were fused. The fusion protein TSTtMr was more efficient and thermostable than the TreS from M. ruber. The N-terminal domain from M. ruber and C terminus from T. thermophilus were fused. The optimum temperature and thermostability of fusion protein TSMrTt were similar to the TreS from M. ruber. It was presumed that aside from the C-terminal domain, the N-terminal domain of TreS from thermophilic bacteria could influence thermostability. For the TreS from M. ruber, the mutant protein R392F led to a complete loss in activity, and R392A showed a sharp decrease in activity.