Plant mitochondria use two pathways for the biogenesis of tRNAHis.
All tRNA(His) possess an essential extra G(-1) guanosine residue at their 5' end. In eukaryotes after standard processing by RNase P, G(-1) is added by a tRNA(His) guanylyl transferase. In prokaryotes, G(-1) is genome-encoded and retained during maturation. In plant mitochondria, although trnH genes possess a G(-1) we find here that both maturation pathways can be used. Indeed, tRNA(His) with or without a G(-1) are found in a plant mitochondrial tRNA fraction. Furthermore, a recombinant Arabidopsis mitochondrial RNase P can cleave tRNA(His) precursors at both positions G(+1) and G(-1). The G(-1) is essential for recognition by plant mitochondrial histidyl-tRNA synthetase. Whether, as shown in prokaryotes and eukaryotes, the presence of uncharged tRNA(His) without G(-1) has a function or not in plant mitochondrial gene regulation is an open question. We find that when a mutated version of a plant mitochondrial trnH gene containing no encoded extra G is introduced and expressed into isolated potato mitochondria, mature tRNA(His) with a G(-1) are recovered. This shows that a previously unreported tRNA(His) guanylyltransferase activity is present in plant mitochondria.
Placido
Antonio
A
Dipartimento di Biochimica e Biologia Molecolare Ernesto Quagliariello, Universita' degli Studi di Bari Aldo Moro, Via Orabona 4, 70126 Bari, Italy.
Sieber
François
F
Gobert
Anthony
A
Gallerani
Raffaele
R
Giegé
Philippe
P
Maréchal-Drouard
Laurence
L
D017360:Arabidopsis / Q000201:enzymology; D002467:Cell Nucleus / Q000201:enzymology; D008928:Mitochondria / Q000201:enzymology / Q000235:genetics*; D009713:Nucleotidyltransferases / Q000032:analysis / Q000378:metabolism; D012313:RNA / Q000096:biosynthesis / Q000145:classification / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D000077278:RNA, Mitochondrial; D018749:RNA, Plant / Q000096:biosynthesis / Q000145:classification / Q000378:metabolism*; D012354:RNA, Transfer, His / Q000096:biosynthesis / Q000145:classification / Q000378:metabolism*; D043262:Ribonuclease P / Q000378:metabolism; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics
D012322:RNA Precursors; D000077278:RNA, Mitochondrial; D018749:RNA, Plant; D012354:RNA, Transfer, His; D012313:RNA; D009713:Nucleotidyltransferases; C065307:tRNA guanylyltransferase; D043262:Ribonuclease P