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J Biol Chem. 2019 Sep 13;294(37):13781-13788. doi: 10.1074/jbc.RA119.009203. Epub 2019 Jul 26.

Mitochondrial cysteinyl-tRNA synthetase is expressed via alternative transcriptional initiation regulated by energy metabolism in yeast cells.

Author information

1
Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
2
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara 630-0192, Japan.
3
Department of Gene Expression Regulation, Institute of Development, Aging, and Cancer, Tohoku University, Sendai 980-8575, Japan.
4
Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan takaike@tohoku.med.ac.jp.

Abstract

Eukaryotes typically utilize two distinct aminoacyl-tRNA synthetase isoforms, one for cytosolic and one for mitochondrial protein synthesis. However, the genome of budding yeast (Saccharomyces cerevisiae) contains only one cysteinyl-tRNA synthetase gene (YNL247W, also known as CRS1). In this study, we report that CRS1 encodes both cytosolic and mitochondrial isoforms. The 5' complementary DNA end method and GFP reporter gene analyses indicated that yeast CRS1 expression yields two classes of mRNAs through alternative transcription starts: a long mRNA containing a mitochondrial targeting sequence and a short mRNA lacking this targeting sequence. We found that the mitochondrial Crs1 is the product of translation from the first initiation AUG codon on the long mRNA, whereas the cytosolic Crs1 is produced from the second in-frame AUG codon on the short mRNA. Genetic analysis and a ChIP assay revealed that the transcription factor heme activator protein (Hap) complex, which is involved in mitochondrial biogenesis, determines the transcription start sites of the CRS1 gene. We also noted that Hap complex-dependent initiation is regulated according to the needs of mitochondrial energy production. The results of our study indicate energy-dependent initiation of alternative transcription of CRS1 that results in production of two Crs1 isoforms, a finding that suggests Crs1's potential involvement in mitochondrial energy metabolism in yeast.

KEYWORDS:

Hap complex; alternative transcription; aminoacyl-tRNA synthetase; cysteinyl-tRNA synthetase; energy metabolism; gene regulation; mitochondrial bioenergetics; transcription; transcriptional start site; yeast

PMID:
31350340
DOI:
10.1074/jbc.RA119.009203
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