1 Department of Chemistry and Biochemistry and Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke St. W., Montréal H4B 1R6, Québec, Canada.
2 Department of Chemistry and Biochemistry and Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke St. W., Montréal H4B 1R6, Québec, Canada. Electronic address: paul.joyce@concordia.ca.

In vitro studies of disease-linked variants of human tRNA nucleotidyltransferase reveal decreased thermal stability and altered catalytic activity.

Biochim Biophys Acta Proteins Proteom. 2018 Apr;1866(4):527-540

Authors: Leibovitch M, Hanic-Joyce PJ, Joyce PBM

Abstract

Mutations in the human TRNT1 gene encoding tRNA nucleotidyltransferase (tRNA-NT), an essential enzyme responsible for addition of the CCA (cytidine-cytidine-adenosine) sequence to the 3'-termini of tRNAs, have been linked to disease phenotypes including congenital sideroblastic anemia with B-cell immunodeficiency, periodic fevers and developmental delay (SIFD) or retinitis pigmentosa with erythrocyte microcytosis. The effects of these disease-linked mutations on the structure and function of tRNA-NT have not been explored. Here we use biochemical and biophysical approaches to study how five SIFD-linked amino acid substitutions (T154I, M158V, L166S, R190I and I223T), residing in the N-terminal head and neck domains of the enzyme, affect the structure and activity of human tRNA-NT in vitro. Our data suggest that the SIFD phenotype is linked to poor stability of the T154I and L166S variant proteins, and to a combination of reduced stability and altered catalytic efficiency in the M158?V, R190I and I223T variants.

PMID: 29454993 [PubMed - indexed for MEDLINE]