| 摘要: | x中文摘要
生物素化是 種必需的維生素與蛋白質的特定賴氨酸殘基共價結合的生物素化作用，由酵母中的生物素蛋白連接酶（BPL1）介導。生物素化是一種罕見的翻譯後修飾，通常發生在位於廣泛分化物種中羧化酶內共有序列（A / V）MKM中的特定賴氨酸殘基上。雖然釀酒酵母的Arc1p缺少共有序列（A / V）MKM，但它在其SSKD處被生物素化。更有趣的是，儘管白色念珠菌（CaH2B）的組蛋白蛋白缺乏（A / V）MKM和SSKD，它們可以在體內生物素化，而釀酒酵母（ScH2B）的組蛋白不能。從Western blot檢測HRP-Streptavidin，我們的結果表明，CaH2B的生物素化似乎是溫度依賴性的;將生長溫度從20℃升高至37℃顯著增加其生物素化水平。基於外源生物素補充劑（〜0.2μg/ L至200μg/ L）的增強，組蛋白的生物素化水平也增加。儘管測試了10種BPL1（ScBPL1，CaBPL1，SpBPL1，PsBPL1，VpBPL1，KlBPL1，LeBPL1，PgBPL1，TpBPL1 ，DhBPL1）可以成功替代ScBPL1敲除菌株，但是它們都不能在釀酒酵母體內對天然組蛋白或CaH2B轉化體進行生物素化。然而，體外生物素化測定結果表明，CaBPL1和ScBPL1都能直接將生物素附著到組蛋白H2B上。這些結果表明釀酒酵母可能含有它們自己的機制來抑制生物素蛋白連接酶在體內對蛋白質組蛋白的生物素化。
關鍵詞：組蛋白，H2B，生物素蛋白連接酶，白色念珠菌，生物素化
;Abstract
Biotinylation, which is covalent binding of a biotin - an essential vitamin to a specific lysine residue of a protein, is mediated by biotin protein ligase (BPL1) in yeast. Biotinylation is a rare post-translational modification and normally occurs in a specific lysine residue positioned in the consensus sequence (A/V)MKM within carboxylases in widely divergent species. While Arc1p of Saccharomyces cerevisiae lacks the consensus sequence (A/V)MKM, it is biotinylated at its SSKD. More interestingly, even though the histone proteins of Candida albicans (CaH2B) lack both (A/V)MKM and SSKD, they can be biotinylated in vivo while histone proteins of S. cerevisiae (ScH2B) cannot. Judging from Western blot probed with HRP-Streptavidin, our results showed that the biotinylation of CaH2B appears to be temperature-dependent; rising the growth temperature from 20oC to 37oC dramatically increased its biotinylation level. Biotinylation level of histones also increased based on the enhancement of exogenous biotin supplement (~0.2 µg/L to 200 μg/L). Despite ten of BPL1s tested (S. cerevisiae BPL1 INVSc1, C. albicans BPL1 SC 5314, S. pombe BPL1 972, and all wild-type of P. stipitis BPL1, V. polyspora BPL1, K. lactis BPL1, L. elongisporus BPL1, P. guilliermondii BPL1, T. phaffii BPL1, D. hansennii BPL1) can successfully substitute ScBPL1 knockout strain, none of them can biotinylate the native histone protein or CaH2B transformants in S. cerevisiae. However, result from in vitro biotinylation assay showed that both of the CaBPL1 and ScBPL1 could attach biotin into the histone protein H2B directly. These results suggesting that S. cerevisiae might contain their own mechanism to inhibit biotinylation of protein histone by biotin protein ligase in vivo.
Keywords: Histone, H2B, biotin protein ligase, Candida albicans, biotinylation |
