Guy Michael P, Shaw Marie, Weiner Catherine L, Hobson Lynne, Stark Zornitza, Rose Katherine, Kalscheuer Vera M, Gecz Jozef, Phizicky Eric M
Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, New York, 14642.
Robinson Research Institute, The University of Adelaide, Adelaide, South Australia 5000, Australia.
Hum Mutat. 2015 Dec;36(12):1176-87. doi: 10.1002/humu.22897. Epub 2015 Sep 10.
tRNA modifications are crucial for efficient and accurate protein synthesis, and modification defects are frequently associated with disease. Yeast trm7Δ mutants grow poorly due to lack of 2'-O-methylated C32 (Cm32 ) and Gm34 on tRNA(Phe) , catalyzed by Trm7-Trm732 and Trm7-Trm734, respectively, which in turn results in loss of wybutosine at G37 . Mutations in human FTSJ1, the likely TRM7 homolog, cause nonsyndromic X-linked intellectual disability (NSXLID), but the role of FTSJ1 in tRNA modification is unknown. Here, we report that tRNA(Phe) from two genetically independent cell lines of NSXLID patients with loss-of-function FTSJ1 mutations nearly completely lacks Cm32 and Gm34 , and has reduced peroxywybutosine (o2yW37 ). Additionally, tRNA(Phe) from an NSXLID patient with a novel FTSJ1-p.A26P missense allele specifically lacks Gm34 , but has normal levels of Cm32 and o2yW37 . tRNA(Phe) from the corresponding Saccharomyces cerevisiae trm7-A26P mutant also specifically lacks Gm34 , and the reduced Gm34 is not due to weaker Trm734 binding. These results directly link defective 2'-O-methylation of the tRNA anticodon loop to FTSJ1 mutations, suggest that the modification defects cause NSXLID, and may implicate Gm34 of tRNA(Phe) as the critical modification. These results also underscore the widespread conservation of the circuitry for Trm7-dependent anticodon loop modification of eukaryotic tRNA(Phe) .
tRNA修饰对于高效且准确的蛋白质合成至关重要，修饰缺陷常与疾病相关。酵母trm7Δ突变体由于tRNA（Phe）上缺乏由Trm7-Trm732和Trm7-Trm734分别催化的2'-O-甲基化的C32（Cm32）和Gm34而生长不良，这进而导致G37处的wybutosine缺失。人类FTSJ1（可能是TRM7的同源物）中的突变会导致非综合征性X连锁智力障碍（NSXLID），但FTSJ1在tRNA修饰中的作用尚不清楚。在此，我们报道来自两个具有功能丧失性FTSJ1突变的NSXLID患者的基因独立细胞系的tRNA（Phe）几乎完全缺乏Cm32和Gm34，并且过氧wybutosine（o2yW37）减少。此外，来自一名具有新型FTSJ1-p.A26P错义等位基因的NSXLID患者的tRNA（Phe）特异性缺乏Gm34，但Cm32和o2yW37水平正常。来自相应酿酒酵母trm7-A26P突变体的tRNA（Phe）也特异性缺乏Gm34，并且Gm34的减少并非由于Trm734结合较弱。这些结果直接将tRNA反密码子环的缺陷性2'-O-甲基化与FTSJ1突变联系起来，表明修饰缺陷导致NSXLID，并可能暗示tRNA（Phe）的Gm34是关键修饰。这些结果还强调了真核tRNA（Phe）依赖Trm7的反密码子环修饰途径的广泛保守性。
