Change search
ReferencesLink to record
Permanent link

Direct link
The yeast initiator tRNAMet can act as an elongator tRNA(Met) in vivo
Umeå University, Faculty of Medicine, Molecular Biology.
Umeå University, Faculty of Medicine, Molecular Biology.
Umeå University, Faculty of Medicine, Molecular Biology. Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
1993 (English)In: Journal of Molecular Biology, ISSN 0022-2836, Vol. 233, no 1, 43-58 p.Article in journal (Refereed) Published
Abstract [en]

Saccharomyces cerevisiae uses two different methionine accepting tRNAs during protein synthesis. One, tRNA(iMet), is used exclusively during the initiation of translation whereas the other, tRNA(mMet), is used during the elongation of translation. To study the unique features of each methionine tRNA species, we constructed yeast strains with null alleles of the five elongator methionine tRNA (EMT) genes and strains with null alleles of the four initiator methionine tRNA (IMT) genes, respectively. Consequently, growth of these strains was dependent either on a tRNA(mMet) or a tRNA(iMet), respectively, encoded from a plasmid-derived gene. For both null mutants, the plasmid carrying the wild-type gene can be selected against and exchanged for another plasmid derived EMT or IMT gene (wild-type or mutant). A high gene dosage of the wild-type IMT gene could restore growth to the elongator-depleted strain. However, wild-type EMT genes in a high gene dosage never restored growth of the initiator depleted strain. Thus, the elongator tRNA(Met) is much more restricted to participate in the initiation of translation than the initiator tRNA(Met) is restricted to participate in the elongation process. Using the two null mutants, we have identified tRNA(mMet) mutants, which show reduced elongator activity, and tRNA(iMet) mutants, with improved elongator activity in the elongator depleted strain. Also, tRNA(mMet) mutants that function as an initiator tRNA in the initiator depleted strain were identified. From this mutant analysis, we showed that the conserved U/rT at position 54 of the elongator tRNA(Met) is an important determinant for an elongator tRNA. The most important determinant for an initiator was shown to be the acceptor stem and especially the conserved A1.U72 base-pair. Mutant tRNAs, with reduced activity in either process, were investigated for enhanced activity during overproduction of the alpha and beta-subunits of the eukaryotic initiation factor 2 (eIF-2) or the eukaryotic elongation factor 1 alpha (eEF-1 alpha). The data suggest that the U/rT of the elongator at position 54 is important for eEF-1 alpha recognition and that the acceptor stem of the initiator is important for eIF-2 recognition.

Place, publisher, year, edition, pages
1993. Vol. 233, no 1, 43-58 p.
Keyword [en]
yeast elongator tRNAMet genes, tRNAMeti, tRNAMetm, elongator/initiator tRNA discrimination, tRNA mutants
National Category
Microbiology in the medical area
URN: urn:nbn:se:umu:diva-32180DOI: 10.1006/jmbi.1993.1483PubMedID: 8377191OAI: diva2:301470
Available from: 2010-03-03 Created: 2010-03-03 Last updated: 2010-03-12Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
von Pawel-Rammingen, UlrichByström, Anders S
By organisation
Molecular BiologyMolecular Biology (Faculty of Science and Technology)
In the same journal
Journal of Molecular Biology
Microbiology in the medical area

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 70 hits
ReferencesLink to record
Permanent link

Direct link