MOD5 translation initiation sites determine N6-isopentenyladenosine modification of mitochondrial and cytoplasmic tRNA.
Open Access
- 1 May 1991
- journal article
- Published by Informa UK Limited in Molecular and Cellular Biology
- Vol. 11 (5), 2382-2390
- https://doi.org/10.1128/mcb.11.5.2382
Abstract
MOD5 is one of several genes that code for enzymes found in mitochondria and another cellular compartment. Like other such genes, it contains two in-frame ATGs that could be used to produce two proteins, differing from each other by an amino-terminal extension. Certain other genes produce heterogeneous mRNAs with some 5' ends falling upstream of the longest open reading frame and some 5' ends falling between the first and second ATGs. In these cases, selection of transcription start sites appears to play a significant role in translation start site selection. MOD5, in contrast, produces mRNAs with 5' ends that all fall upstream of both ATGs. To determine how MOD5 encodes isozymes that are located in different cellular compartments and to determine whether they differ in structure, we constructed MOD5 and MOD5-COXIV fusions with mutations of the first, second, or both ATGs. The effect of these alterations on protein production, tRNA modification, and cellular location was assessed. Both the first and second ATGs are used to produce MOD5 protein in vivo, but only the long form of the protein is imported into mitochondria. Thus, the first 11 amino acids present on the amino-terminal extended protein are necessary for mitochondrial import. Surprisingly, this extension does not promote complete import of the long form of the protein, but rather a functional pool of the extended protein remains in the cytoplasm. The amino-terminal extension is also unusual because it is probably not proteolytically removed upon import and therefore does not constitute part of a mitochondrial presequence.Keywords
This publication has 41 references indexed in Scilit:
- N2,N2-dimethylguanosine-specific tRNA methyltransferase contains both nuclear and mitochondrial targeting signals in Saccharomyces cerevisiae.The Journal of cell biology, 1989
- Amino-terminal extension generated from an upstream AUG codon increases the efficiency of mitochondrial import of yeast N2,N2-dimethylguanosine-specific tRNA methyltransferases.Molecular and Cellular Biology, 1989
- Cyclosporin A-binding protein (cyclophilin) of Neurospora crassa. One gene codes for both the cytosolic and mitochondrial forms.Journal of Biological Chemistry, 1988
- THE YEAST VAS1 GENE ENCODES BOTH MITOCHONDRIAL AND CYTOPLASMIC VALYL-TRANSFER RNA-SYNTHETASES1988
- Yeast LEU4 encodes mitochondrial and nonmitochondrial forms of alpha-isopropylmalate synthase.Journal of Biological Chemistry, 1988
- Mitochondrial and cytoplasmic fumarases in Saccharomyces cerevisiae are encoded by a single nuclear gene FUM1.Journal of Biological Chemistry, 1987
- Amino-terminal extension generated from an upstream AUG codon is not required for mitochondrial import of yeast N2,N2-dimethylguanosine-specific tRNA methyltransferase.Proceedings of the National Academy of Sciences, 1987
- Regulated overproduction of the GAL4 gene product greatly increases expression from galactose-inducible promoters on multi-copy expression vectors in yeastGene, 1987
- Structure of yeast LEU4. The 5' flanking region contains features that predict two modes of control and two productive translation starts.Journal of Biological Chemistry, 1986
- A complementation analysis of the restriction and modification of DNA in Escherichia coliJournal of Molecular Biology, 1969