The Purple Membrane Regulon in a Haloarchaeon

盐古菌中的紫膜调节子

• 批准号: 0095700
• 负责人: Shiladitya DasSarma
• 金额: $ 43.01万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2001-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0095700&HistoricalAwards=false
• 关键词: Purple; Membrane; Regulon; Haloarchaeon

0095700 DasSarma and SchreierIn this project, a combination of genetic and biochemical approaches are being used to investigate purple membrane synthesis in a salt-loving archaeon, Halobacterium NRC-1. The purple membrane is a specialized region of the cell membrane that contains a two-dimensional crystalline array of a single chromoprotein, bacteriorhodopsin (BR). BR is composed of a 1:1 complex of the protein moiety (bacterio-opsin) and chromophore (retinal). When fully induced under microaerobic and high illumination conditions, purple membrane can cover up to 50 % of the cell's surface and is able to support a period of phototrophic growth. Previously, transcription of the bop gene was shown to depend upon an upstream gene, bat, and found to be sensitive to DNA supercoiling. Additionally, the minimal bacterio-opsin gene (bop) promoter was extensively mutagenized and shown to contain an essential upstream activator sequence (UAS), a TATA box deviating from the archaeal consensus, and a DNA supercoiling-sensitivity site within an alternating purine-pyrimidine region. The likely regulator, Bat, contains homologies to the PAS-PAC (or LOV) redox sensing domain, a GAF light-responsive domain, and an AraC type helix-turn-helix (HTH) DNA binding motif. Three other genes (crtB1, blp, and brp) containing UAS elements similar to the bop gene, and clustered immediately upstream of bop, showed similar or identical regulatory characteristics, and six TATA-binding protein (tbp) genes and seven TFIIB (tfb) genes were found in the genome sequence. The major goal of this project is to understand the mechanism of coordinate regulation of bacterio-opsin and retinal at the genetic level. Specifically, the project will (1) identify the proteins binding to the bop promoter, (2) define the mechanism of action of the pleiotropic regulator, Bat, in concert with other transcriptional factors, and (3) establish the members of the purple membrane regulon. The long-term goal is to better understand the mechanisms of coordinate regulation of multigene systems in archaea, which should shed light on the evolution of regulatory mechanisms across all branches of life.

0095700 DasSarma和Schreier在这个项目中，遗传和生物化学方法的组合被用来研究嗜盐古菌，盐杆菌NRC-1中的紫膜合成。 紫膜是细胞膜的一个特殊区域，包含一个单一的色蛋白，细菌视紫红质（BR）的二维晶体阵列。 BR由蛋白质部分（细菌视蛋白）和发色团（视网膜）的1：1复合物组成。 当在微氧和高光照条件下完全诱导时，紫膜可以覆盖高达50%的细胞表面，并且能够支持一段时间的光养生长。 以前，bop基因的转录被证明依赖于上游基因bat，并且被发现对DNA超螺旋敏感。 此外，最小的细菌视蛋白基因（bop）启动子被广泛诱变，并显示含有一个必需的上游激活序列（UAS），一个TATA盒偏离古细菌的共识，和一个DNA超螺旋敏感性位点内的交替嘌呤嘧啶区域。 可能的调节剂，蝙蝠，含有同源性的PAS-PAC（或LOV）氧化还原敏感结构域，GAF光响应结构域，和AraC型螺旋-转角-螺旋（HTH）DNA结合基序。 其他三个基因（crtB 1，blp和brp）含有UAS元件类似的bop基因，并聚集在bop的上游，表现出相似或相同的调控特性，和六个TATA结合蛋白（tbp）基因和七个TFIIB（tfb）基因被发现在基因组序列。 本项目的主要目的是从基因水平上了解细菌视蛋白和视网膜的协同调控机制。 具体而言，该项目将（1）鉴定与bop启动子结合的蛋白质，（2）确定多效性调节因子Bat与其他转录因子的作用机制，以及（3）建立紫膜调节子的成员。 长期目标是更好地了解古细菌中多基因系统的协调调节机制，这应该有助于了解生命所有分支的调节机制的进化。