ANKRD16 prevents neuron loss caused by an editing-defective tRNA synthetase

Abstract

Editing domains of aminoacyl tRNA synthetases correct tRNA charging errors to maintain translational fidelity. A mutation in the editing domain of alanyl tRNA synthetase (AlaRS) in Aarssti mutant mice resulted in an increased production of serine-mischarged tRNAAla and degeneration of cerebellar Purkinje cells. By positional cloning, we identified Ankrd16, which acts epistatically with the Aarssti mutation to attenuate neurodegeneration. ANKRD16, a vertebrate-specific, ankyrin repeat-containing protein, binds directly to the catalytic domain of AlaRS. Serine misactivated by AlaRS is captured by lysine side chains of ANKRD16, preventing the charging of serine adenylates to tRNAAla and precluding serine misincorporation in nascent peptides. Deletion of Ankrd16 in the Aarssti/sti brain causes widespread protein aggregation and neuron loss. These results identify a novel amino acid-accepting co-regulator of tRNA synthetase editing as a new layer of the machinery essential for preventing severe pathologies that arise from defects in editing.

Alanyl-tRNA Synthetase Quality Control Prevents Global Dysregulation of the Escherichia coli Proteome

“…In addition to endogenous proofreading activity, AlaRS can resample aa-tRNAs, leading to mis-aminoacyl-tRNA hydrolysis. Furthermore, at least three free-standing enzymes, AlaXP (13), Dtd (15), and ANKRD16 in vertebrates (14), have been identified in vivo to prevent mischarged tRNA Ala species from accumulating. Additional factors, such as ProXPST1, have also been identified to have proofreading activity in vitro against these aa-tRNAs, but their role in vivo has yet to be well characterized (43).…”

“…coli a strong model for studying AlaRS mistranslation, as there is not a redundant mechanism to correct Ser-tRNA Ala product formation. Recently, a novel trans -editing factor, ANKRD16, was identified in vertebrates which binds to Ser-AMP in complex with AlaRS, preventing the transfer onto tRNA Ala (14). Finally, the d -tyrosyl deacylase (DTD) whose function was originally characterized to prevent d -amino acid aminoacylation was found to have proofreading activity against Gly-tRNA Ala (15).…”

Aminoacyl-tRNA synthetases

“…Recently, an additional mechanism preventing Ser-to-Ala misincorporation has been described in the ANKRD16 protein. ANKRD16 is a vertebratespecific, ankyrin repeat-containing protein that binds to the catalytic domain of AlaRS and is able to remove the misactivated serine in a tRNA-independent manner, incorporating the serine into ANKRD16 (Vo et al 2018). The role that ANKRD16 plays in preventing serine mistranslation has not been described before for any synthetase, and although it may be Surface residues substituted with methionine could potentially neutralize the highly reactive species produced under oxidative stress, preventing the oxidation of sensitive amino acid chains at the active site that would result in permanent inactivation of the enzyme.…”

RNA mimicry in post‐transcriptional regulation by aminoacyl tRNA synthetases

“…These trans‐editing factors provide an additional charging proofreading, and can act either before the amino acid had been attached to the tRNA, or by cleaving out the mischarged amino acid after the tRNA had been charged and is about to dissociate from its aaRS (Ling et al, ; Jakubowski, ). Recently, ANKRD16 was found as an AlaRS trans‐editor that acts before mischarging of tRNA Ala and prevents neuron loss, further exemplifying the physiological significance of this proofreading step in higher eukaryotes (Vo et al, ).…”

“…Both structures are of T. thermophilus proteins, and were modeled by PyMOL the tRNA had been charged and is about to dissociate from its aaRS (Ling et al, 2009;Jakubowski, 2012). Recently, ANKRD16 was found as an AlaRS trans-editor that acts before mischarging of tRNA Ala and prevents neuron loss, further exemplifying the physiological significance of this proofreading step in higher eukaryotes (Vo et al, 2018).…”