Stoichiometry of mitochondrial transcripts and regulation of gene expression by mitochondrial transcription factor A.
The steady state concentration of cytochrome c oxidase subunit I mRNA and 12 S rRNA, respectively, measured by a quantitative reverse transcription/polymerase chain reaction method, was 4 and 15 molecules per molecule of mt DNA in rat liver and 2 and 9 molecules in rat muscle, respectively. These results imply that in the mitochondrial compartment, the molar concentration of all thirteen mRNAs by far exceeds the concentration of ribosomes, a situation fundamentally different from the cytosolic compartment. Following thyroid hormone treatment, both mitochondrial transcripts increased, in parallel with the mRNA encoding mitochondrial transcription factor A. We conclude that this transcription factor might be the rate limiting factor for mitochondrial transcription in vivo, at least under these conditions.
Garstka
H L
HL
Department of Physiology II, University of Heidelberg, Germany.
Fäcke
M
M
Escribano
J R
JR
Wiesner
R J
RJ
D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004268:DNA-Binding Proteins; D003576:Electron Transport Complex IV / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D006980:Hyperthyroidism / Q000201:enzymology / Q000378:metabolism; D007037:Hypothyroidism / Q000201:enzymology / Q000378:metabolism; D046911:Macromolecular Substances; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism*; D008931:Mitochondria, Muscle / Q000201:enzymology / Q000378:metabolism*; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D012016:Reference Values; D015534:Trans-Activators; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D014158:Transcription, Genetic; D029867:Xenopus Proteins
D017931:DNA Primers; D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D012335:RNA, Ribosomal; C075526:RNA, ribosomal, 12S; D011994:Recombinant Proteins; C499631:TFAM protein, human; C489030:Tfam protein, rat; D015534:Trans-Activators; D014157:Transcription Factors; C097078:XL-MTTFA protein, Xenopus; D029867:Xenopus Proteins; C422562:mitochondrial transcription factor A; D003576:Electron Transport Complex IV