The Usher Syndrome Type IIIB Histidyl-tRNA Synthetase Mutation Confers Temperature Sensitivity

Authors

Jamie A Abbott, University of Vermont
Ethan Guth, Norwich University
Cindy Kim, Western University
Cathy Regan, Western University
Victoria M Siu, Western University
C Anthony Rupar, Western University
Borries Demeler, The University of Texas Health Science Center at San Antonio
Christopher S Francklyn, University of Vermont
Susan M Robey-Bond, University of Vermont

Document Type

Article

Publication Date

7-18-2017

Journal

Biochemistry

Volume

56

Issue

28

First Page

3619

Last Page

3631

URL with Digital Object Identifier

https://doi.org/10.1021/acs.biochem.7b00114

Abstract

Histidyl-tRNA synthetase (HARS) is a highly conserved translation factor that plays an essential role in protein synthesis. HARS has been implicated in the human syndromes Charcot-Marie-Tooth (CMT) Type 2W and Type IIIB Usher (USH3B). The USH3B mutation, which encodes a Y454S substitution in HARS, is inherited in an autosomal recessive fashion and associated with childhood deafness, blindness, and episodic hallucinations during acute illness. The biochemical basis of the pathophysiologies linked to USH3B is currently unknown. Here, we present a detailed functional comparison of wild-type (WT) and Y454S HARS enzymes. Kinetic parameters for enzymes and canonical substrates were determined using both steady state and rapid kinetics. Enzyme stability was examined using differential scanning fluorimetry. Finally, enzyme functionality in a primary cell culture was assessed. Our results demonstrate that the Y454S substitution leaves HARS amino acid activation, aminoacylation, and tRNA