An evolutionarily conserved translation initiation mechanism regulates nuclear or mitochondrial targeting of DNA ligase 1 inArabidopsis thaliana
| Autor: | Christopher E. West, Paul A. Sunderland, Clifford M. Bray, Wanda M. Waterworth |
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| Rok vydání: | 2006 |
| Předmět: |
Gene isoform
Chloroplasts DNA Ligases Recombinant Fusion Proteins Green Fluorescent Proteins Molecular Sequence Data Nuclear Localization Signals Arabidopsis Codon Initiator Plant Science Protein Sorting Signals Biology Ribosome Protein Structure Secondary Evolution Molecular DNA Ligase ATP Eukaryotic translation Start codon Genetics Protein Isoforms RNA Messenger Peptide Chain Initiation Translational Gene Cell Nucleus chemistry.chemical_classification DNA ligase Messenger RNA Base Sequence Arabidopsis Proteins Cell Biology Mitochondria Cell biology Protein Transport chemistry Nuclear localization sequence |
| Zdroj: | The Plant Journal. 47:356-367 |
| ISSN: | 1365-313X 0960-7412 |
| Popis: | The Arabidopsis DNA ligase 1 gene (AtLIG1) is indispensable for cell viability. AtLIG1 expresses one major and two minor mRNA transcripts differing only in the length of the 5' untranslated leader sequences preceding a common ORF. Control of AtLIG1 isoform production and intracellular targeting depends upon mechanisms controlling the choice of translation initiation site within the AtLIG1 ORF. Confocal laser scanning microscopy of green fluorescent protein-tagged AtLIG1 isoforms expressed in Arabidopsis revealed that translation of AtLIG1 mRNA transcripts from the first in-frame start codon produces an AtLIG1 isoform that is targeted exclusively to the mitochondria. Translation initiation from the second in-frame start codon produces an AtLIG1 isoform targeted only to the nucleus. There is no evidence for AtLIG1-GFP being targeted to chloroplasts. The mitochondrial AtLIG1 isoform possesses both an N-terminal mitochondrial-targeting signal and an internal bipartite nuclear localization signal (NLS) yet is targeted only to mitochondria, demonstrating a hierarchical dominance of the mitochondrial presequence over the NLS. The length of the 5'-UTR and more significantly the nucleotide context around alternative start codons in the AtLIG1 transcripts affect translation initiation to ensure a balanced synthesis of both nuclear and mitochondrial AtLIG1 isoforms, probably via a context-dependent leaky ribosome scanning mechanism. |
| Databáze: | OpenAIRE |
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