The Bipartite Structure of the tRNA m¹A58 Methyltransferase from S. cerevisiae is Conserved in Humans

Authors

Sarah G. Ozanick, Marquette University
Annette M. Krecic, Marquette University
Joshua Andersland, College of St. Scholastica
James T. Anderson, Marquette UniversityFollow

Document Type

Article

Language

eng

Format of Original

10 p.

Publication Date

2005

Publisher

Cold Spring Harbor Laboratory Press

Source Publication

RNA

Source ISSN

1355-8382

Original Item ID

doi: 10.1261/rna.5040605; PubMed Central, PMCID: PMC1370811

Abstract

Among all types of RNA, tRNA is unique given that it possesses the largest assortment and abundance of modified nucleosides. The methylation at N₁ of adenosine 58 is a conserved modification, occurring in bacterial, archaeal, and eukaryotic tRNAs. In the yeast Saccharomyces cerevisiae, the tRNA 1-methyladenosine 58 (m¹A58) methyltransferase (Mtase) is a two-subunit enzyme encoded by the essential genes TRM6 (GCD10) and TRM61 (GCD14). While the significance of many tRNA modifications is poorly understood, methylation of A58 is known to be critical for maintaining the stability of initiator tRNA^Met in yeast. Furthermore, all retroviruses utilize m¹A58-containing tRNAs to prime reverse transcription, and it has been shown that the presence of m¹A58 in human tRNA₃ ^Lys is needed for accurate termination of plus-strand strong-stop DNA synthesis during HIV-1 replication. In this study we have identified the human homologs of the yeast m¹A Mtase through amino acid sequence identity and complementation of trm6 and trm61 mutant phenotypes. When coexpressed in yeast, human Trm6p and Trm61p restored the formation of m¹A in tRNA, modifying both yeast initiator tRNA^Met and human tRNA₃ ^Lys. Stable hTrm6p/hTrm61p complexes purified from yeast maintained tRNA m¹A Mtase activity in vitro. The human m¹A Mtase complex also exhibited substrate specificity—modifying wild-type yeast tRNA_i ^Met but not an A58U mutant. Therefore, the human tRNA m¹A Mtase shares both functional and structural homology with the yeast tRNA m¹A Mtase, possessing similar enzymatic activity as well as a conserved binary composition.

Comments

Published version. RNA, Vol. 11, No. 8 (2005): 1281-1290. DOI. © 2005 Cold Spring Harbor Laboratory Press. Used with permission.

Recommended Citation

Ozanick, Sarah G.; Krecic, Annette M.; Andersland, Joshua; and Anderson, James T., "The Bipartite Structure of the tRNA m¹A58 Methyltransferase from S. cerevisiae is Conserved in Humans" (2005). Biological Sciences Faculty Research and Publications. 355.
https://epublications.marquette.edu/bio_fac/355