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Transcriptome and growth efficiency comparisons of recombinant thermophiles that produce thermolabile and thermostable proteins: implications for burden-based selection of thermostable proteins
Extremophiles ( IF 2.9 ) Pub Date : 2021-06-30 , DOI: 10.1007/s00792-021-01237-w
Hirokazu Suzuki 1, 2 , Yuta Okumura 3 , Yui Mikawa 1 , Mao Takata 1 , Shunsuke Yoshimura 3 , Takashi Ohshiro 1, 2
Affiliation  

Geobacillus kaustophilus is a thermophilic bacterium that grows at temperatures ranging between 42 and 74 °C. Here, we modified this organism to produce the thermolabile protein (PyrFA) or its thermostable variant (PyrFV) and analyzed the transcriptome and growth efficiency profiles of the resultant strains. In the producer of PyrFA, the transcriptome profile was changed to facilitate ATP synthesis from NADH without pooling reduced quinones. This change implies that PyrFA production at elevated temperatures places an energy burden on cells potentially to maintain protein homeostasis. This was consistent with the observation that the PyrFA producer grew slower than the PyrFV producer at > 45 °C and had a lower cellular fitness. Similar growth profiles were also observed in the PyrFA and PyrFV producers derived from another thermophile (Geobacillus thermodenitrificans) but not in those from Escherichia coli at 30 °C. Thus, we suggest that the production of thermolabile proteins impairs host survival at higher temperatures; therefore, thermophiles are under evolutionary selection for thermostable proteins regardless of whether their functions are associated with survival advantages. This hypothesis provides new insights into evolutionary protein selection in thermophiles and suggests an engineering approach to select thermostable protein variants generated via random gene mutagenesis.



中文翻译:

产生不耐热和耐热蛋白质的重组嗜热菌的转录组和生长效率比较:对基于负荷的耐热蛋白质选择的影响

Geobacillus kaustophilus是一种嗜热细菌,可在 42 至 74 °C 的温度范围内生长。在这里,我们修改了这种生物体以产生不耐热蛋白质 (PyrF A ) 或其热稳定变体 (PyrF V ),并分析了所得菌株的转录组和生长效率谱。在 PyrF A的生产者中,转录组谱被改变以促进从 NADH 合成 ATP,而不合并还原的醌。这种变化意味着高温下PyrF A 的产生会给细胞带来潜在的能量负担,以维持蛋白质稳态。这与观察结果一致,即 PyrF A生产者的生长速度比 PyrF V生产者在 > 45 °C 并且具有较低的细胞适应性。在来自另一种嗜热菌(嗜热地芽孢杆菌)的 PyrF A和 PyrF V生产者中也观察到了类似的生长曲线,但在 30 °C 时在来自大肠杆菌的那些生产者中没有观察到。因此,我们认为不耐热蛋白质的产生会损害宿主在较高温度下的生存。因此,无论它们的功能是否与生存优势相关,嗜热菌都在进化选择耐热蛋白质。这一假设为嗜热菌的进化蛋白质选择提供了新的见解,并提出了一种选择通过随机基因诱变产生的热稳定蛋白质变体的工程方法。

更新日期:2021-06-30
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