Hong Dawei, Saidel William M, Man Shushuang, Martin Joseph V
Department of Computer Science, Rutgers University, Camden, NJ 08102, USA.
J Theor Biol. 2007 Apr 21;245(4):726-36. doi: 10.1016/j.jtbi.2006.12.006. Epub 2006 Dec 12.
Quorum sensing is a bacterial mechanism used to synchronize the coordinated response of a microbial population. Because quorum sensing in Gram-negative bacteria depends on release and detection of a diffusible signaling molecule (autoinducer) among a multicellular group, it is considered a simple form of cell-cell communication for the purposes of mathematical analysis. Stochastic equation systems have provided a common approach to model biochemical or biophysical processes. Recently, the effect of noise to synchronize a specific homogeneous quorum sensing network was successfully modeled using a stochastic equation system with fixed parameters. The question remains of how to model quorum sensing networks in a general setting. To address this question, we first set a stochastic equation system as a general model for a heterogeneous quorum sensing network. Then, using two relevant biophysical characteristics of Gram-negative bacteria (the permeability of the cell membrane to the autoinducer and the symmetry of autoinducer diffusion) we construct the solution of the stochastic equation system at an abstract level. The solution indicates that stable synchronization of a quorum sensing network is robustly induced by an environment with a heterogenous distribution of extracellular and intracellular noise. The synchronization is independent of the initial state of the system and is solely the result of the connectivity of the cell network established through the effects of extracellular noise.
群体感应是一种细菌机制，用于同步微生物群体的协同反应。由于革兰氏阴性菌中的群体感应依赖于多细胞群体中可扩散信号分子（自诱导物）的释放和检测，从数学分析的角度来看，它被认为是一种简单的细胞间通讯形式。随机方程系统为生化或生物物理过程建模提供了一种常用方法。最近，利用具有固定参数的随机方程系统成功地对噪声同步特定均匀群体感应网络的效果进行了建模。然而，如何在一般情况下对群体感应网络进行建模仍是一个问题。为了解决这个问题，我们首先将随机方程系统设定为异质群体感应网络的通用模型。然后，利用革兰氏阴性菌的两个相关生物物理特性（细胞膜对自诱导物的通透性和自诱导物扩散的对称性），在抽象层面构建随机方程系统的解。该解表明，细胞外和细胞内噪声异质分布的环境能稳健地诱导群体感应网络的稳定同步。这种同步与系统的初始状态无关，完全是通过细胞外噪声的作用建立的细胞网络连通性的结果。
