Protein turnover forms one of the highest maintenance costs in Lactococcus lactis
Protein turnover forms one of the highest maintenance costs in Lactococcus lactis
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DOI：
10.1099/mic.0.078089-0
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发表时间：
2014-07-01
期刊：
影响因子：
2.8
通讯作者：
Vilu, Raivo
中科院分区：
文献类型：
--
作者：
Lahtvee, Petri-Jaan;Seiman, Andrus;Vilu, Raivo
蛋白质周转通过调节代谢通量在细胞代谢中起重要作用。此外，据估计，蛋白质周转的能量成本占细胞复制期间总能量生产的三分之一，因此可能是实现更高生物量或产量的主要限制因素。本研究旨在测量单个蛋白质的特定生长率（mu）依赖性丰度和周转率，估计蛋白质生产和周转率的ATP成本，并将其与总能量平衡和其他维持成本进行比较。在恒化实验中，采用乳酸菌模式生物乳酸球菌（Lacto coccus lactis）在mu=0.1和0.5 h（-1）时测定蛋白质周转率。测量了总蛋白质组的75%的个体周转率。平均而言，蛋白质周转量增加了7倍，生长率增加了5倍，而生物量产量增加了35%。发现的中位数周转率高于细菌的特定生长率，这表明蛋白质周转率的能量消耗相对较高。我们发现，在mu=0.1和0.5 h（-1）时，仅蛋白质周转成本就分别占总能量的38%和47%，而在两种生长速率下，基因本体组能量代谢和翻译主导合成成本。这些结果反映了在环境条件变化下发生的代谢变化的复杂性，并表明了生物量产量与维持过程所需ATP之间的权衡。
Protein turnover plays an important role in cell metabolism by regulating metabolic fluxes. Furthermore, the energy costs for protein turnover have been estimated to account for up to a third of the total energy production during cell replication and hence may represent a major limiting factor in achieving either higher biomass or production yields. This work aimed to measure the specific growth rate (mu)-dependent abundance and turnover rate of individual proteins, estimate the ATP cost for protein production and turnover, and compare this with the total energy balance and other maintenance costs. The lactic acid bacteria model organism Lacto coccus lactis was used to measure protein turnover rates at mu=0.1 and 0.5 h(-1) in chemostat experiments. Individual turnover rates were measured for similar to 75% of the total proteome. On average, protein turnover increased by sevenfold with a fivefold increase in growth rate, whilst biomass yield increased by 35%. The median turnover rates found were higher than the specific growth rate of the bacterium, which suggests relatively high energy consumption for protein turnover. We found that protein turnover costs alone account for 38 and 47% of the total energy produced at mu=0.1 and 0.5 h(-1), respectively, and gene ontology groups Energy metabolism and Translation dominated synthesis costs at both growth rates studied. These results reflect the complexity of metabolic changes that occur in response to changes in environmental conditions, and signify the trade-off between biomass yield and the need to produce ATP for maintenance processes.