FUNCTIONS OF tRNA MODIFICATIONS

tRNA 修饰的功能

• 批准号: 7582509
• 负责人: Ya-Ming Hou
• 金额: $ 30.9万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-15 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7582509
• 关键词: Active Sites; Address; Anabolism; Anticodon; Archaea; Bacteria; Binding; Biochemical; Catalysis; Cleaved cell; Communication; Complement; Complex; Coupled; Dissection; Drug Delivery Systems; Drug Design; Ensure; Enzymatic Biochemistry; Enzymes; Escherichia coli; Eukaryota; Eukaryotic Cell; Foundations; Frequencies; Genes; Genetic; Genetic Transcription; Goals; Growth; Health; Healthcare; Human; Kinetics; Life; Methionine; Modification; Molecular; Molecular Conformation; Monitor; Movement; Nucleic Acids; Pharmaceutical Preparations; Positioning Attribute; Preparation; Process; Protein Biosynthesis; Proteins; Public Health; Purpose; Rate; Reaction; Reading Frames; Resources; Ribosomes; Role; S-Adenosylmethionine; Salmonella typhimurium; Side; Site; Solid; Specificity; Streptococcus pneumoniae; Structure; Testing; Transfer RNA; Transferase; Translating; Vertebral column; analog; base; cell growth; cofactor; fitness; improved; insight; interest; methyl group; pathogen; research study; success; tool

DESCRIPTION (provided by applicant): Modifications of transfer RNA (tRNA) molecules occur after transcription and constitute an essential step to promote cellular fitness and viability. Of interest is the m1G37 modification, which takes place at almost all tRNA molecules that have the G37 base immediately adjacent to the 3' side of the anticodon sequence. The m1G37 modification is important for maintaining the tRNA reading frame specificity on the ribosome during protein synthesis. Elimination of this modification increases ribosomal errors in protein synthesis and elevates frequencies of frame shifts. The enzyme that catalyzes the m1G37 modification is tRNA(m1G37) methyl transferase, which transfers the methyl group of S-adenosyl methionine (AdoMet) to the N1 position of G37 in tRNA. The bacterial enzyme, known as TrmD (encoded by the trmD gene), is essential for growth in E. coli, Salmonella typhimurium, and Streptococcus pneumoniae. An unexpected recent finding is that while TrmD is highly conserved among bacterial species, it shares little sequence or structural homology with its eukaryotic and archaeal counterpart (known as Trm5, encoded by the trm5 gene). This establishes TrmD and Trm5 as a pair of analogous enzymes that use distinct structural folds to catalyze the same reaction to synthesize the growth-dependent m1G37 in tRNA. The separation of TrmD and Trm5 along the split of bacteria from eukarya- archaea thus raises the medically relevant and attractive prospect of selective targeting of the bacterial TrmD. This proposal is aimed at providing a strong biochemical and molecular foundation that is necessary for the success of such drug targeting. Two aims of the project are to determine the molecular and structural basis of TrmD and Trm5 for their recognition of AdoMet and tRNA and the dynamic recognition process that leads to catalysis. The third aim will determine the role of the m1G37 modification on the ribosome during the decoding process. Together, these aims combine the strengths and interests of two presently separate fields (enzymology of tRNA modification, and ribosome structure and function) to address key issues that will have long-term impact on human health and bio-defense against bacterial pathogens. PUBLIC HEALTH RELEVANCE: The cellular protein synthesis machinery provides the basis for translating genetic information stored in nucleic acids to functional proteins. This machinery depends on extensive tRNA-ribosome interactions to ensure the fidelity of protein synthesis. The m1G37 modification of tRNA is a key determinant of this fidelity and is essential for growth for several bacterial pathogens. However, the molecular and biochemical basis for how the m1G37 modification is synthesized and how it functions on the ribosome is poorly understood. Preliminary studies show that the enzyme that catalyzes the m1G37 synthesis in bacteria was of a different structural origin from its counterpart in eukaryotes and in archaea. This proposal is aimed at elucidating the molecular basis for the enzymatic synthesis of m1G37 and the differences between the bacterial and eukaryotic/archaeal enzymes. Information to be gained from this proposal will provide important insights to build a solid foundation for selective inhibition of the bacterial enzyme so as to improve human health care.

描述（由申请人提供）：转录后发生转移RNA（TRNA）分子的修饰，并构成促进细胞适应性和生存力的重要步骤。感兴趣的是M1G37修饰，它发生在几乎所有具有G37碱基紧邻反激代序列3'侧的g37碱基的tRNA分子上。 M1G37修饰对于在蛋白质合成过程中维持核糖体的tRNA读数框架特异性很重要。消除这种修饰会增加蛋白质合成中的核糖体误差，并提高帧移位频率。催化M1G37修饰的酶是tRNA（M1G37）甲基转移酶，该酶将S-腺苷蛋氨酸（ADOMET）的甲基甲基转移到tRNA中G37的N1位置。细菌酶，称为TRMD（由TRMD基因编码），对于大肠杆菌，鼠伤寒沙门氏菌和肺炎链球菌的生长至关重要。最近的一个出乎意料的发现是，尽管TRMD在细菌物种中高度保守，但它与其真核和古细菌对应物（称为TRM5，由TRM5基因编码）共享几乎没有序列或结构同源性。这将TRMD和TRM5建立为一对类似酶，它们使用不同的结构折叠来催化相同的反应以合成tRNA中生长依赖性的M1G37。因此，TRMD和TRM5沿着细菌与真核古细菌的分裂散发出了选择性靶向细菌TRMD的医学相关和有吸引力的前景。该提案旨在提供强大的生化和分子基础，这对于这种药物靶向的成功所必需。该项目的两个目的是确定TRMD和TRM5的分子和结构基础，以识别ADOMET和TRNA以及导致催化的动态识别过程。第三个目标将确定M1G37修饰在解码过程中核糖体上的作用。这些目标共同结合了两个目前分开的领域（tRNA修饰的酶学以及核糖体结构和功能）的优势和利益，以解决将对人类健康和对细菌病原体的生物防御产生长期影响的关键问题。公共卫生相关性：细胞蛋白合成机制为将核酸中存储的遗传信息转换为功能蛋白提供了基础。该机械取决于广泛的tRNA-核糖体相互作用，以确保蛋白质合成的保真度。 tRNA的M1G37修饰是该保真度的关键决定因素，对于几种细菌病原体的生长至关重要。但是，如何合成M1G37修饰的分子和生化基础以及它在核糖体上的功能的理解很少。初步研究表明，催化细菌中M1G37合成的酶与其在真核生物和古细菌中的结构起源不同。该建议旨在阐明M1G37酶促合成的分子基础以及细菌和真核/古细菌酶之间的差异。从本提案中获得的信息将提供重要的见解，为选择性抑制细菌酶建立坚实的基础，从而改善人类卫生保健。