| Infection of prion protein can result in a series of transmissible spongiform encephalopathy (TSE) diseases in human and animals, including Kuru disease, GSS, FFI, CJD, BSE and scrapie etc. These progressive neurodegenerative diseases result from structural and conformational change from cellμlor prion protein (PrPc) to the infectious prion protein particles (PrPSc). There were no nucleic acids found in the infectious prion protein particles. The mechanism of PrPc converting to PrPSc remains unclear.TSE diseases in human and animals caused a major threat to the health and affect the development of agricμlture. We generated polyclonal antibodies against the bovine prion protein and used the antibodies to detect cattle and sheep in Xinjiang region of China. BSE and scrapie could not be found by this method, which may suggest that cattle and sheep in Xinjiang be relatively healthy.Currently, amino acid sequences of PrP has been obtained from more than40species of animals. Rabbit is one of the few species which has never been found infected by prion disease so far. Prion disease spreading among species has "species barrier". The species specificity is due to several amino acids differences in the primary structure, which result in a different three-dimensional conformation of PrP with different local spatial structure of proteins, hydrogen distribution, structural stability and dynamics characteristics, thus affecting the interaction between different molecμles.The study of rabbit prion protein (RabPrP) was limited, and its physicochemical property is not clear. In order to further reveal the mechanisms why rabbit is resistant to TSE infections, it is necessary to investigate the physicochemical properties and stability of RabPrP. There are22different amino acids in the primary structure of mature mouse and rabbit PrPc,and their homology is87%. The conparison and analysis of physicochemical properties of RabPrP, BoPrP, and MoPrP will facilitatee the revelation of the molecular mechanism of the resistance of rabbit to transmissible spongiform encephalopathies infection. In this study, three recombinant mature prion proteins have been expressed and purified. The circular dichroism test, fluorescence spectra scanning and proteinase K assay etc have been carried out to detect the structural characteristics of the proteins.The results showed that under acidic conditions, the secondary structure of BoPrP and MoPrP exhibited a consistent change, but RabPrP showed a slow structural change when the ambient pH decreased. ANS fluorescence test has also proven that the structure of RabPrP is relatively more stable in the acidic condition, and compared to BoPrP and MoPrP, the hydrophobic globμlar domain of RabPrP exposed slowly. Also, the thermal stability of the three prion protein has been tested, and the Tm value of RabPrP is much higher than that of BoPrPand MoPrP, which validates that RabPrP is more stable in thermal condition. Under acidic conditions, along with low concentration denaturant, the three prion proteins can form a certain amount of polymer, which performs proteinase K-resistant property. In comparison with the other two prion proteins, polymer formed from RabPrP is slightly less and proteinase K-resistant capacity is also low. These resμlts show that the RabPrP is unique, and the property difference at the protein level, may reveal the possible reason why the rabbit is not easiely infected by TSE. These resμlts may help to reveal the infection mechanism of the TSEIn vitro, prion protein and KCTD1has high affinity to associate. Study of characteristics and function of KCTD1will help to reveal the pathogenic mechanism of prion disease. In this study, the KCTD1protein has been expressed and purified, and the secondary structure, thermal stability, and structural characteristics of FCCTD1protein have also been analysed by circμlar dichroism technique, which will facilitate further study of KCTD1function in cells, and the exploration of KCTD1interaction with PrPs was urgently expected. |
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