School of Physics, University of New South Wales, Sydney, NSW, Australia.
The Ithree Institute, University of Technology Sydney, Sydney, NSW, Australia.
PLoS One. 2017 Oct 17;12(10):e0185947. doi: 10.1371/journal.pone.0185947. eCollection 2017.
The Min protein system creates a dynamic spatial pattern in Escherichia coli cells where the proteins MinD and MinE oscillate from pole to pole. MinD positions MinC, an inhibitor of FtsZ ring formation, contributing to the mid-cell localization of cell division. In this paper, Fourier analysis is used to decompose experimental and model MinD spatial distributions into time-dependent harmonic components. In both experiment and model, the second harmonic component is responsible for producing a mid-cell minimum in MinD concentration. The features of this harmonic are robust in both experiment and model. Fourier analysis reveals a close correspondence between the time-dependent behaviour of the harmonic components in the experimental data and model. Given this, each molecular species in the model was analysed individually. This analysis revealed that membrane-bound MinD dimer shows the mid-cell minimum with the highest contrast when averaged over time, carrying the strongest signal for positioning the cell division ring. This concurs with previous data showing that the MinD dimer binds to MinC inhibiting FtsZ ring formation. These results show that non-linear interactions of Min proteins are essential for producing the mid-cell positioning signal via the generation of second-order harmonic components in the time-dependent spatial protein distribution.
Min 蛋白系统在大肠杆菌细胞中创建了一个动态的空间模式，其中 MinD 和 MinE 蛋白从极到极振荡。MinD 定位 MinC，MinC 是 FtsZ 环形成的抑制剂，有助于细胞分裂的中体定位。在本文中，傅里叶分析被用于将实验和模型 MinD 空间分布分解为随时间变化的谐和分量。在实验和模型中，第二谐和分量负责在 MinD 浓度中产生中体最小值。这个谐和分量的特征在实验和模型中都是稳健的。傅里叶分析揭示了实验数据和模型中谐和分量随时间变化的行为之间的密切对应关系。有鉴于此，对模型中的每个分子物种进行了单独分析。该分析表明，膜结合的 MinD 二聚体在时间平均时显示出最高对比度的中体最小值，对定位细胞分裂环具有最强的信号。这与先前的数据一致，表明 MinD 二聚体与 MinC 结合，抑制 FtsZ 环的形成。这些结果表明，Min 蛋白的非线性相互作用对于通过在时间相关的空间蛋白分布中产生二阶谐和分量来产生中体定位信号是必不可少的。
