The 7472insC mtDNA mutation impairs 5' and 3' processing of tRNA(Ser(UCN)).
The deafness-associated 7472insC mtDNA mutation was previously shown to decrease the steady-state level of tRNA(Ser(UCN)) post-transcriptionally. To identify the affected tRNA maturation step(s) we analysed the effects of the mutation on processing in vivo and in vitro. tRNA(Ser(UCN)) from cybrid cells homoplasmic for 7472insC contained a high frequency (>11%) of molecules misprocessed at one or both termini. In vitro assays using partially purified HeLa cell RNase P and mitochondrial tRNA 3' processing endonuclease (tRNase Z) confirmed that the efficiency of both 5' and 3' processing was impaired. A mutant precursor not already processed at the 5' end was poorly processed in vitro by tRNase Z. Misprocessing at the 3' end further impaired the efficiency and accuracy of 5' processing of the mutant substrate. The mutation thus appears to affect several distinct, but interdependent, RNA processing steps, with the predicted outcome dependent on the exact processing pathway operating in vivo.
Toompuu
Marina
M
Institute of Medical Technology and Tampere University Hospital, FI-33014 University of Tampere, Finland.
Levinger
Louis L
LL
Nadal
Anna
A
Gomez
Jordi
J
Jacobs
Howard T
HT
D020121:5' Untranslated Regions / Q000235:genetics; D001483:Base Sequence; D001859:Bone Neoplasms; D045744:Cell Line, Tumor; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D012516:Osteosarcoma; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics; D012362:RNA, Transfer, Ser / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020121:5' Untranslated Regions; D017931:DNA Primers; D004272:DNA, Mitochondrial; D012362:RNA, Transfer, Ser