Genetic Regulation of Bioluminescence in Marine Bacteria

本研究的目的是了解调控哈维弧菌发光表达的遗传控制机制。海洋细菌中发光基因的表达受细胞密度和各种环境因素的控制。密度依赖性调节是光通量调节的一个主要方面，由细胞外信号物质介导，称为自诱导剂。两种自诱导剂信号通路收敛控制紫花苜蓿的发光。其中一个通路，信号系统1，由产生自诱导器1 （AI-1信号）和响应同源自诱导器（AI-1传感器）的功能组成。luxL和luxM基因是产生AI-1所必需的，luxN基因编码AI-1传感器。第二种途径，信号系统2，由产生自动诱导器2 （AI-2信号）和响应该信号（AI-2传感器）的功能组成。luxP和luxQ基因编码AI-2传感器蛋白。这两种信号通路在luxO基因编码的控制功能上相交。LuxO蛋白整合了传感器1和2的响应，在luxR基因产物的参与下，激活编码发光酶的luxCDABE操纵子的转录。勒克斯调节显然是复杂的，许多功能和相互作用仍有待确定。该项目包括突变体分离，以指导其他调控基因的克隆、测序和表征，特别是那些生产自诱导剂2 （AI-2）所需的基因。来自各种lux调节基因的转录本正在被绘制和量化，以分析调节回路中的层次和反馈关系。传感器1和传感器3功能缺陷的突变体将受到各种环境信号的刺激，以检测与其他感觉系统的交叉通信。定点诱变将用于获得锁定或异常的Lux信号蛋白，然后用于检查调节成分的在线相互作用和信号转导的生物化学。分析勒克斯系统对于理解细菌如何感知环境和对环境作出反应是有价值的。调控过程复杂，涉及细胞间和细胞内的信号传递，因此可能会揭示有趣的新机制。然而，复杂性不应该成为障碍，因为感官输入（化学信号）和输出（光发射）可以方便地控制和测量，遗传方法也很发达。＊＊＊

9419862 Silverman The objective of this investigation is to understand the genetic control mechanisms which regulate expression of luminescence in the bacterium Vibrio harveyi. Expression of genes for luminescence (lux) in marine bacteria is controlled by cell density and a variety of environmental cues. Density-dependent regulation is a primary facet of lux regulation and is mediated by extracellular signal substances called autoinducers. Two autoinducer signaling pathways converge to control luminescence in V. harveyi. One pathway, signaling system 1, consists of functions for production of autoinducer 1 (AI-1 Signal) and for response to the cognate autoinducer (AI-1 Sensor). The luxL and luxM genes are required for AI-1 production, and luxN encodes the AI-1 Sensor. A second pathway, signaling system 2, consists of functions for production of autoinducer 2 (AI-2 Signal) and for response to this signal (AI-2 Sensor). The luxP and luxQ genes encode AI-2 Sensor proteins. Both signaling pathways intersect at a control function encoded by the luxO gene. The LuxO protein integrates the responses of both Sensors 1 and 2 and, with the participation of the luxR gene product, activates transcription of the luxCDABE operon encoding the luminescence enzymes. Lux regulation is apparently complicated, and many functions and interactions remain to be identified. This project includes mutant isolation to guide the cloning, sequencing and characterization of additional regulatory genes, particularly those required for production of autoinducter 2 (AI-2). Transcripts from various lux regulatory genes are being mapped and quantitated to analyze hierarchical and feedback relationships in the regulatory circuitry. Mutants defective both in sensor 1 and 3 function will be stimulated with a variety of environmental signals to detect cross-communication with other sensory systems. Site-directed mutagenesis will be used to obtain locked or aberrant Lux signaling proteins which will then be used to exam ine interactions of regulatory components and the biochemistry of signal transduction. %%% Analyzing the lux system should be valuable for understanding how bacteria perceive and react to their environment. The regulatory process is complex and involves both intercellular and intracellular signal transmission so interesting new mechanisms could be revealed. However, complexity should not be a barrier because the sensory input (chemical signals) and the output (light emission) can be conveniently controlled and measured, and the genetic methodology is well-developed. ***