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A single point mutation of hamster aminoacyl‐tRNA synthetase causes apoptosis by deprivation of cognate amino acid residue
Author(s) -
Fukushima Kohtaro,
Motomura Seiichi,
Kuraoka Akio,
Nakano Hitoo,
Nishimoto Takeharu
Publication year - 1996
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.1996.d01-225.x
Subject(s) - biology , mutant , cycloheximide , aminoacyl trna synthetase , microbiology and biotechnology , point mutation , hamster , biochemistry , mutation , cell culture , gene , apoptosis , lysine , transfer rna , amino acid , protein biosynthesis , rna , genetics
Background:We have isolated a series of temperature‐sensitive mutants for cell‐proliferation from the BHK21 cell line derived from the golden hamster (Nishimoto & Basilico 1978; Nishimoto et al. 1982). Using these mutants as a recipient of DNA‐mediated gene transfer, we have been cloning human genes which complement these ts mutants.Results:Cultures of tsBN269 cells, a temperature‐sensitive mutant of the BHK21 cell line, underwent apoptosis at 39.5 °C, a nonpermissive temperature. The gene complementing the tsBN269 cells was cloned and found to encode lysyl‐tRNA synthetase. Indeed, tsBN269 cells were found to have a single cytosine to a thymine point mutation at the first nucleotide of codon 542 in hamster lysyl‐tRNA synthetases. Due to this mutation, the activity of lysyl‐tRNA synthetase was reduced—even at 33.5 °C, a permissive temperature. Consistent with these findings, while supplementation with lysine permitted tsBN269 cells to grow at a nonpermissive temperature, the deprivation of lysine caused apoptosis in tsBN269 cells, even at 33.5 °C. Cycloheximide inhibited the apoptosis caused by lysine starvation at 33.5 °C, but not at 39.5 °C. We also found that another hamster temperature‐sensitive mutant, tsBN250, which is defective in histidyl‐tRNA synthetase, entered apoptosis with the deprivation of histidine.Conclusion:Our data suggested that the defect in aminoacyl‐tRNA synthetase turned on the cascade of apoptosis that was already present in the cells.