Regulation of the B. Subtilis trp Genes by the trp RNA- binding Attenuation Protein (TRAP)

近年来，RNA结合蛋白作为基因表达调控因子的重要性日益明确。枯草芽孢杆菌的trp基因受一种称为TRAP （trp RNA结合衰减蛋白）的RNA结合蛋白调控。TRAP通过三种方式调节trp基因的表达，这三种方式都涉及色氨酸依赖的TRAP与RNA的结合。trpEDCFBA操纵子的转录受一种衰减机制控制。TRAP与trp操纵子转录体先导序列中含有11个（G/U）AG重复的位点结合，会影响衰减子的二级结构，促进转录终止子的形成。TRAP还调节trpE和trpG基因的翻译。TRAP通过改变mRNA先导序列的二级结构来隔离trpE mRNA的核糖体结合位点，并直接与核糖体竞争与trpG mRNA的结合。最近对trap - l -色氨酸复合物的x射线晶体学分析揭示了一个由11个相同的亚基组成的新型大分子，这些亚基排列成环状结构，具有23埃的空穴。每个亚基完全由-股、-匝和随机线圈组成。TRAP是一种11个亚基的蛋白质，其trp RNA结合位点包含多个小序列重复，这一发现导致了一个模型，在这个模型中，trp RNA包裹着TRAP，因此trp RNA先导序列中的11个重复中的每一个都与一个TRAP亚基或邻近亚基的组合相互作用。本研究的目的是精确确定TRAP如何识别其靶RNA，包括鉴定TRAP的RNA结合结构域和TRAP靶RNA特异性的决定因素，以及表征TRAP - RNA相互作用的动力学和热力学。这项研究将提供关于蛋白质如何识别RNA的新信息，并将更好地理解蛋白质-RNA相互作用的基本原理，这可能会影响真核生物中更复杂的转录、翻译、RNA加工和运输过程。近年来，RNA结合蛋白作为基因表达调控因子的重要性日益明确。枯草芽孢杆菌中负责色氨酸生物合成的基因受一种称为TRAP （trp RNA结合衰减蛋白）的RNA结合蛋白调控，该蛋白需要氨基酸色氨酸与RNA结合。最近的结构分析表明，TRAP是一种由11个相同的亚基组成的新型大分子。这项研究将确定TRAP如何识别和结合其靶RNA，并将提供新的信息和更好地理解蛋白质-RNA相互作用的基本原理，这可能会影响真核生物中更复杂的转录、翻译、RNA加工和运输过程。

9603594 Gollnick The importance of RNA binding proteins as regulators of gene expression has become increasingly clear in recent years. The trp genes of Bacillus subtilis are regulated by an RNA binding protein called TRAP (trp RNA-binding Attenuation Protein). TRAP regulates the expression of trp genes in three ways which all involve tryptophan-dependent binding of TRAP to RNA. Transcription of the trpEDCFBA operon is controlled by an attenuation mechanism. TRAP binding to a site containing 11 (G/U)AG repeats in the leader sequence of trp operon transcript affects the secondary structure of the attenuator and promotes formation of a transcription terminator. TRAP also regulates translation of the trpE and trpG genes. TRAP is proposed to sequester the ribosome binding site of the trpE mRNA by altering the secondary structure of the mRNA leader sequence, and to compete directly with ribosomes for binding to the trpG mRNA. Recent X-ray crystallographic analysis of the TRAP-L-tryptophan complex revealed a novel macromolecule consisting of 11 identical subunits arranged in ring structure with a 23 Angstrom hole. Each subunit is composed entirely of beta-strands, beta-turns and random coils. The discoveries that TRAP is an 11-subunit protein and that its trp RNA binding site contains multiple small sequence repeats has led to a model in which the trp RNA wraps around the TRAP so that each of the 11 repeats in the trp RNA leader sequence interacts with one TRAP subunit or a combination of adjacent subunits. The objective of this research is to determine precisely how TRAP recognizes its target RNAs including the identification of the RNA binding domain of TRAP and the determinants of target RNA specificity for TRAP, and the characterization of the kinetics and thermodynamics of TRAP - RNA interaction. This research will provide new information about how proteins recognize RNA and will result in better understanding of the basic principles of protein-RNA interaction that may govern more com plicated processes of transcription, translation, RNA processing and transport in eukaryotes. The importance of RNA binding proteins as regulators of gene expression has become increasingly clear in recent years. The genes responsible for tryptophan biosynthesis in the bacteria Bacillus subtilis are regulated by an RNA binding protein called TRAP (trp RNA-binding Attenuation Protein), which requires the amino acid tryptophan to bind to RNA. Recent structural analysis indicates that TRAP is a novel macromolecule consisting of 11 identical subunits arranged in ring structure. This research will determine how TRAP recognizes and binds to its target RNA, and will provide new information and a better understanding of the basic principles of protein-RNA interaction that may govern more complicated processes of transcription, translation, RNA processing and transport in eukaryotes.