Zhulin I B
School of Biology, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332-0230, USA.
Adv Microb Physiol. 2001;45:157-98. doi: 10.1016/s0065-2911(01)45004-1.
Chemotaxis transducers are specialized receptors that microorganisms use in order to sense the environment in directing their motility to favorable niches. The Escherichia coli transducers are models for studying the sensory and signaling events at the molecular level. Extensive studies in other organisms and the arrival of genomics has resulted in the accumulation of sequences of many transducer genes, but they are not fully understood. In silico analysis provides some assistance in classification of various transducers from different species and in predicting their function. All transducers contain two structural modules: a conserved C-terminal multidomain module, which is a signature element of the transducer superfamily, and a variable N-terminal module, which is responsible for the diversity within the superfamily. These structural modules have two distinct functions: the conserved C-terminal module is involved in signaling and adaptation, and the N-terminal module is involved in sensing various stimuli. Both C-terminal and N-terminal modules appear to be mobile genetic elements and subjects of duplication and lateral transfer. Although chemotaxis transducers are found exclusively in prokaryotic organisms that have some type of motility (flagellar, gliding or pili-based), several types of domains that are found in their N-terminal modules are also present in signal transduction proteins from eukaryotes, including humans. This indicates that basic principles of sensory transduction are conserved throughout the phylogenetic tree and that the chemotaxis transducer superfamily is a valuable source of novel sensory elements yet to be discovered.
趋化转导器是微生物用来感知环境，从而将其运动导向有利生态位的特殊受体。大肠杆菌转导器是在分子水平上研究感觉和信号传导事件的模型。在其他生物体中的广泛研究以及基因组学的出现，导致了许多转导器基因序列的积累，但人们对它们还没有完全了解。计算机分析为不同物种的各种转导器分类以及预测其功能提供了一些帮助。所有转导器都包含两个结构模块：一个保守的C端多结构域模块，它是转导器超家族的标志性元件；以及一个可变的N端模块，它负责超家族内的多样性。这些结构模块具有两种不同的功能：保守的C端模块参与信号传导和适应性调节，而N端模块参与感知各种刺激。C端和N端模块似乎都是可移动遗传元件，是复制和横向转移的对象。尽管趋化转导器仅存在于具有某种运动方式（鞭毛运动、滑行运动或菌毛运动）的原核生物中，但在其N端模块中发现的几种结构域也存在于包括人类在内的真核生物的信号转导蛋白中。这表明感觉转导的基本原理在整个系统发育树中是保守的，并且趋化转导器超家族是尚未被发现的新型感觉元件的宝贵来源。
