arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1104.4092q-bio.CBphysics.bio-phq-bio.SC
收藏

自适应信令网络的噪声滤波策略:E。大肠杆菌趋化性

Noise Filtering Strategies of Adaptive Signaling Networks: The Case of E. Coli Chemotaxis

Pablo Sartori, Yuhai Tu

摘要:

在一类自适应感觉网络中,识别了两种不同的过滤输入信号中噪声的机制。我们发现,高频噪声通过时间平均的输出退化过程过滤,而低频噪声通过负反馈自适应阻尼。两个滤波过程本身都引入了固有噪声,发现这些噪声未被滤波,因此即使没有信令,也可以达到显著的内部噪声基底。这些结果应用于E.大肠杆菌趋化性。我们明确地表明,伯格-珀塞尔时间平均计划的分子机制是反应调节剂CheY-P的去磷酸化,而不是如前所述的受体适应过程。由于随机配体结合-解结合事件和随机配体分子扩散而产生的高频噪声通过CheY-P去磷酸化过程在大肠杆菌中平均到可忽略的水平。我们确定了一个以前未研究的噪声源所造成的随机运动的细胞在配体梯度。我们发现,这种随机游走诱导的信号噪声有一个发散的低频分量,这是只呈现有限的受体适应过程。对于E. coli传感范围内,这种占主导地位的外部噪声可以与系统中的显著固有噪声相媲美。系统地研究了系统的响应及其涨落对关键时间尺度的依赖性。我们表明,趋化性途径可能已经进化到优化梯度感应,强反应,和噪声控制在不同的时间尺度

英文摘要:

Two distinct mechanisms for filtering noise in an input signal are identified in a class of adaptive sensory networks. We find that the high frequency noise is filtered by the output degradation process through time-averaging; while the low frequency noise is damped by adaptation through negative feedback. Both filtering processes themselves introduce intrinsic noises, which are found to be unfiltered and can thus amount to a significant internal noise floor even without signaling. These results are applied to E. coli chemotaxis. We show unambiguously that the molecular mechanism for the Berg-Purcell time-averaging scheme is the dephosphorylation of the response regulator CheY-P, not the receptor adaptation process as previously suggested. The high frequency noise due to the stochastic ligand binding-unbinding events and the random ligand molecule diffusion is averaged by the CheY-P dephosphorylation process to a negligible level in E.coli. We identify a previously unstudied noise source caused by the random motion of the cell in a ligand gradient. We show that this random walk induced signal noise has a divergent low frequency component, which is only rendered finite by the receptor adaptation process. For gradients within the E. coli sensing range, this dominant external noise can be comparable to the significant intrinsic noise in the system. The dependence of the response and its fluctuations on the key time scales of the system are studied systematically. We show that the chemotaxis pathway may have evolved to optimize gradient sensing, strong response, and noise control in different time scales

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑