AtTrm5a catalyses 1-methylguanosine and 1-methylinosine formation on tRNAs and is important for vegetative and reproductive growth in Arabidopsis thaliana

First author: Xiaohuan Jin; Affiliations: HuaZhong Agricultural University (华中农业大学): Wuhan, China

Corresponding author: Peng Chen

Modified nucleosides on tRNA are critical for decoding processes and protein translation. tRNAs can be modified through 1-methylguanosine (m1G) on position 37; a function mediated by Trm5 homologs. We show that AtTRM5a (At3g56120) is a Trm5 ortholog in Arabidopsis thaliana. AtTrm5a is localized to the nucleus and its function for m1G and m1I methylation was confirmed by mutant analysis, yeast complementation, m1G nucleoside level on single tRNA, and tRNA in vitro methylation. Arabidopsis attrm5a mutants were dwarfed and had short filaments, which led to reduced seed setting (结实). Proteomics data indicated differences in the abundance of proteins involved in photosynthesis, ribosome biogenesis, oxidative phosphorylation (氧化磷酸化) and calcium signalling (钙信号). Levels of phytohormone auxin and jasmonate were reduced in attrm5a mutant, as well as expression levels of genes involved in flowering, shoot apex cell fate determination, and hormone synthesis and signalling. Taken together, loss-of-function of AtTrm5a impaired m1G and m1I methylation and led to aberrant (异常的) protein translation, disturbed hormone homeostasis and developmental defects in Arabidopsis plants.

tRNA上的核苷酸修饰对于解码和蛋白质翻译过程是非常重要的。Trm5同源物能够介导tRNA的37号位置上发生m1G甲基化。本文中，作者的研究显示AtTRM5a基因，即At3g56120是拟南芥中Trm5的同源基因。AtTrm5a定位于细胞核，作者通过突变体研究、酵母互补试验、单个tRNA上的m1G核苷酸水平、以及体外tRNA甲基化等试验确定了AtTrm5a能够作用于m1G和m1I甲基化。拟南芥attrm5a突变体矮化，花丝变短，并导致了结实率降低。蛋白组数据显示光合作用、核糖体生物发生、氧化磷酸化和钙信号相关的蛋白表现出差异。attrm5a突变体中植物激素生长素和茉莉酸的含量也有所减少，同时开花、茎尖细胞命运决定及植物激素合成和信号转导相关基因的表达水平也降低。综上，AtTrm5a的功能丢失导致了m1G和m1I甲基化受损，进而导致了蛋白翻译的异常，最终干扰了拟南芥植株中植物激素的内稳态和正常发育。

通讯：陈鹏 (http://cpst.hzau.edu.cn/info/1016/1967.htm)

个人简介：2004-2006年，瑞典于默奥大学, 博士后；2006-2010年，于默奥植物科学中心，瑞典农业大学，博士后/研究助理。

研究方向：利用tRNA修饰核苷调控在高等植物中的作用研究。

doi: https://doi.org/10.1093/nar/gky1205

Journal: Nucleic Acids Research

Published date: 01 December, 2018