Biochemistry of lysyl-tRNA synthetases

描述（由申请人提供）：氨基酰基- trna合成酶负责氨基酸和trna的配对，对核糖体蛋白合成和翻译外的其他过程都至关重要。氨酰基- trna合成酶家族还包含许多类似物，这些类似物概括了氨酰基- trna合成酶的催化核心或各种附加结构域。在细菌中，典型的赖氨酸- trna合成酶提供翻译赖氨酸密码子和修饰膜脂的底物，而密切相关的类似物PoxA则参与延伸因子P的翻译后修饰，这是对沙门氏菌等病原体的毒力至关重要的途径。在这两种情况下，赖氨酸-tRNA合成酶型蛋白促进非tRNA分子赖氨酸化的能力对细胞具有广泛的影响，决定了诸如抗生素耐药性等关键特性。本提案的目的是建立在我们早期对赖氨酸- trna合成酶家族的研究基础上，研究赖氨酸- trna合成酶及其类似物的非规范作用。具体来说，我们将确定：i) lysyl-tRNA在脂质修饰中的作用的结构和功能基础。ii)赖氨酸- trna合成酶和PoxA识别发散底物的分子基础。iii)修饰的伸长因子p的作用机制。本工作将揭示赖氨酸- trna合成酶家族成员参与蛋白质合成外的氨基酰化反应的分子机制，并将揭示蛋白质和脂质的氨基酰化如何为这些分子提供新的和必需的生物活性。了解赖氨酸- trna合成酶家族在细胞中发挥如此广泛作用的结构和功能特征，也将为其他氨基酰基- trna合成酶蛋白家族提供可能的新功能的见解，其中绝大多数包含许多不知道功能的保守的类似物。

DESCRIPTION (provided by applicant): The aminoacyl-tRNA synthetases are responsible for pairing amino acids and tRNAs, and are crucial both for ribosomal protein synthesis and other processes outside translation. The aminoacyl-tRNA synthetase family also contains numerous paralogs that recapitulate either the catalytic core or the various appended domains of aminoacyl-tRNA synthetases. In bacteria the canonical lysyl-tRNA synthetase provides substrates both to translate lysine codons and to modify membrane lipids, while the closely related paralog PoxA instead participates in the post-translational modification of elongation factor P, a pathway critical for the virulence of pathogens such as Salmonella. In both instances, the ability of lysyl-tRNA synthetase-type proteins to promote lysylation of molecules other than tRNA has widespread effects on the cell, determining key properties such as antibiotic resistance. The objective of this proposal is to build on our earlier work on the lysyl-tRNA synthetase family to study non-canonical roles of lysyl-tRNA synthetases and their paralogs. Specifically, we will determine: i) The structural and functional basis of lysyl-tRNA's role in lipd modification. ii) The molecular basis of divergent substrate recognition by lysyl-tRNA synthetase and PoxA. iii) The mechanism of action of modified elongation factor P. This work will reveal the molecular mechanisms that allow members of the lysyl-tRNA synthetase family to participate in aminoacylation reactions outside protein synthesis, and will show how the aminoacylation of proteins and lipids can provide these molecules with new and essential biological activities. Understanding the structural and functional features that allow the lysyl-tRNA synthetase family to play such broad roles in the cell will also provide insights into possible new functions in othe aminoacyl-tRNA synthetase protein families, the vast majority of which contain numerous well-conserved paralogs with no known function.