Divergent evolution of a bifunctional de novo protein
Divergent evolution of a bifunctional de novo protein
复制标题
双功能从头蛋白质的发散进化
作者：
Betsy A. Smith;Ann E. Mularz;M. Hecht
原始蛋白质，现代序列的进化祖先，被认为是最低限度的活性和非特异性。在经历了选择压力之后，这些早期的祖细胞进化成高度活性和特异性的蛋白质。虽然从不活跃和多功能的通才到高度活跃的专家的进化轨迹在进化史上可能发生过多次，但这样的途径很难在自然系统中重建，因为原始序列已经丢失。为了验证这一假设，即选择增强活性导致滥交的损失，我们进化了从头设计的双功能蛋白质。从二元模式化的4-螺旋束文库中选择亲本蛋白，表示为Syn-IF。Syn‐IF先前已被证明可以拯救两种不同的营养缺陷型E. coli中的ΔilvA和Δfes。这两种菌株含有具有非常不同的生化功能的蛋白质的缺失; IlvA参与异亮氨酸生物合成，而Fes参与铁同化。在两个独立的实验中，Syn‐IF被进化为更快地拯救ΔilvA或Δfes。在多轮诱变后，选择了两种新的蛋白质，每种蛋白质能够比亲本蛋白质显著更快地挽救所选择的功能。在每一种情况下，进化的蛋白质也失去了拯救神经元功能的能力。在这两种进化轨迹中，最初的双功能多面手都进化为活动增强的单功能专家。
Primordial proteins, the evolutionary ancestors of modern sequences, are presumed to have been minimally active and nonspecific. Following eons of selective pressure, these early progenitors evolved into highly active and specific proteins. While evolutionary trajectories from poorly active and multifunctional generalists toward highly active specialists likely occurred many times in evolutionary history, such pathways are difficult to reconstruct in natural systems, where primordial sequences are lost to time. To test the hypothesis that selection for enhanced activity leads to a loss of promiscuity, we evolved a de novo designed bifunctional protein. The parental protein, denoted Syn‐IF, was chosen from a library of binary patterned 4‐helix bundles. Syn‐IF was shown previously to rescue two different auxotrophic strains of E. coli: ΔilvA and Δfes. These two strains contain deletions for proteins with very different biochemical functions; IlvA is involved in isoleucine biosynthesis, while Fes is involved in iron assimilation. In two separate experiments, Syn‐IF, was evolved for faster rescue of either ΔilvA or Δfes. Following multiple rounds of mutagenesis, two new proteins were selected, each capable of rescuing the selected function significantly faster than the parental protein. In each case, the evolved protein also lost the ability to rescue the unselected function. In both evolutionary trajectories, the original bifunctional generalist was evolved into a monofunctional specialist with enhanced activity.
影响因子：
56.9
作者：
Sarkar, Indrani;Hauber, Ilona;Buchholz, Frank
通讯作者：
Buchholz, Frank
影响因子：
10.7
作者：
Patrick, Wayne M.;Quandt, Erik M.;Matsumura, Ichiro
通讯作者：
Matsumura, Ichiro