| Summary: | 碩士 === 國立中央大學 === 生物資訊與系統生物研究所 === 96 === Trichomonas vaginalis, an anaerobic, parasitic flagellated protozoan resides mostly in female vagina, urethra, uterus as well as male prostate gland, is the causative agent of the most common nonviral sexually transmitted infections (STIs) in the world, human trichomoniasis. Recently, multiple surface adhesion proteins have been shown to be engaged in Cytoadherence, an essential step, of the T. vaginalis infection. The ap65-1 gene, a member of the adhesion protein 65 (ap65) multigene family, encodes for multiple homologous 65-kDa proteins, was found to be regulated by transcription factors, Myb1 and Myb2 proteins, in T. vaginalis.
Two DNA sequences, MRE1/MRE2r and MRE2f, on the gene, ap65-1, is recognized by Myb protein; this discovery deduce the possible involvement of Myb-like transcription factors related to the transcription mechanism within T. vaginalis. From various experiments, evidences show a specific interaction between full-length Myb2 protein with MRE1/MRE2r and MRE2f. We have found that a truncated fragment of Myb2, designated as Myb2x, consisting of amino acid V40–M156 displays similar DNA affinity. This fragment was employed for affinity binding and NMR structure-dynamic studies.
By NMR relaxation technology, the difference in dynamics between Myb2x free, Myb2x-MRE1/MRE2r and Myb2x- MRE2f complex forms was resolved. 15N spin relaxation rates and heternuclear (15N-1H) NOE were measured by standard pulse sequences at static magnetic field of 14.7 Tesla. The relaxation data were further analyzed with reduced spectral density mapping approach to deduce the spectral density functions: J(0), J(ωN) and J(ω0.87H) . The protein dynamics of Myb2x, as revealed by the reduced spectral density functions, are mapped onto the structures of the free and DNA-bound forms of Myb2x. The results showed that binding of DNA tighten the protein structure considerably. Such information will be useful for design of effective drugs for the treatment of human trichomoniasis.
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