来自现代 (+) - 胚芽蛋白A合成酶的α-humulene合成酶重建的进化和机械学的见解
Veronica Gonzalez1, Sabrina Touchet, Daniel J Grundy
1School of Chemistry and ‡Cardiff Catalysis Institute, School of Chemistry, Cardiff University , Main Building, Park Place, Cardiff CF10 3AT, United Kingdom.
Journal of the American Chemical Society
|September 18, 2014
概括
通过改变活性部位残留物,研究了Germacrene A合成酶 (GAS) 的活性. 在GAS中取代甘氨酸402和在GDS中取代甘氨酸404揭示了基合成酶的进化途径.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 有机化学 有机化学
背景情况:
- 甲合成酶 (SPSs) 是植物二次新陈代谢中的关键酶.
- 来自Solidago canadensis的基尔马克林A合成酶 (GAS) 通常通过1,10循环化产生 (+) - 基尔马克林A.
- 一个较小的产物,α-烯,由1,11-循环形成,这表明它可能具有双重活性.
研究的目的:
- 调查 GAS.中的 1,10-vs. 1,11-循环选择性的结构和机制基础.
- 为了探索1,10-和1,11-sésquiterpene合成酶之间的进化关系.
- 了解特定活性部位残留物在控制循环路径中的作用.
主要方法:
- 1,10-和1,11-合成酶的氨基酸序列对齐.
- 气体的X射线结晶学和同质模型.
- 在GAS (Gly402) 和GDS (Gly404) 的位点定向突变发生.
- 使用同位素标记法纳西二酸盐 (FDP) 和乳标记的机制研究.
主要成果:
- 在GAS中识别了Thr401-Gly402-Gly403三合体,可能对1,10循环化负责.
- 在GAS中Gly402的突变性逐渐增加了1,11-循环活动.
- 在GDS中Gly404的变异产生了双循环基马克林,表明了双 1,10-/1,11-循环化.
- 机理学研究支持将这些通路连接起来的生殖 - 烯重排.
结论:
- Gly402作为一个功能开关,控制气体中的1,10-vs.1,11-循环.
- 具有严格功能的酶可能通过微小的替代物从不太特定的祖先进化.
- 对于germacrenes和humulenes的反应途径可能通过一个共同的中间体联系在一起.
- 现代的1,10-合成酶可能是从杂乱的1,11-六次合成酶进化出来的.
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