| Summary: | 碩士 === 國立海洋大學 === 水產生物技術研究所 === 83 ===
UBF is an RNA polymerase I transcription factor which recognizes crossover DNA structure with low sequence specificity. The structure-specific DNA binding activity of UBF is carried out by its mutiple HMG-like DNA binding domains, especially by its first domain-HMG box1. Functional UBF protein associates as homooligomer form when they are synthesized both in vivo and in vitro. UBF oligomerization domain is located at its amino terminal humdred amino acides. E. coli expressed UBF amino-terminal 110 amino acids, including UBF oligomerization domain and next lysine--rich residues, binds double--stranded DNA without any sequence specificity and makes even-distributed ladders in gel-shift DNA binding assay. The function of UBF oligomerizationwas carried out by the residues started from the 19th residues. Mutaions on most of hydrophobic residues in the UBF oligomerization domain severely damage protein oligomerization. The UBF aminoterminal residues notably binds DNA as trimer form, as suggested from this study. In contrast, oligomerization-defected proteins bind DNA as monomer form.
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