Human Mitochondrial Transcription Initiation Complexes Have Similar Topology on the Light and Heavy Strand Promoters

Transcription is a highly regulated process in all domains of life. In human mitochondria, transcription of the circular genome involves only two promoters, called light strand promoter (LSP) and heavy strand promoter (HSP), located in the opposite DNA strands. Initiation of transcription occurs upo...

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Bibliographic Details
Published in:The Journal of biological chemistry 2016-06, Vol.291 (26), p.13432-13435
Main Authors: Morozov, Yaroslav I., Temiakov, Dmitry
Format: Article
Language:English
Subjects:
DNA, Mitochondrial - genetics
DNA, Mitochondrial - metabolism
DNA-Binding Proteins - genetics
DNA-Binding Proteins - metabolism
Humans
LSP
Methyltransferases - genetics
Methyltransferases - metabolism
Mitochondria - genetics
Mitochondria - metabolism
mitochondrial DNA (mtDNA)
Mitochondrial Proteins - genetics
Mitochondrial Proteins - metabolism
mtRNAP
promoter
Promoter Regions, Genetic - physiology
protein cross-linking
RNA polymerase
TFAM
TFB2M
transcription
transcription factor
Transcription Factors - genetics
Transcription Factors - metabolism
Transcription Initiation, Genetic - physiology
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Summary:Transcription is a highly regulated process in all domains of life. In human mitochondria, transcription of the circular genome involves only two promoters, called light strand promoter (LSP) and heavy strand promoter (HSP), located in the opposite DNA strands. Initiation of transcription occurs upon sequential assembly of an initiation complex that includes mitochondrial RNA polymerase (mtRNAP) and the initiation factors mitochondrial transcription factor A (TFAM) and TFB2M. It has been recently suggested that the transcription initiation factor TFAM binds to HSP and LSP in opposite directions, implying that the mechanisms of transcription initiation are drastically dissimilar at these promoters. In contrast, we found that binding of TFAM to HSP and the subsequent recruitment of mtRNAP results in a pre-initiation complex that is remarkably similar in topology and properties to that formed at the LSP promoter. Our data suggest that assembly of the pre-initiation complexes on LSP and HSP brings these transcription units in close proximity, providing an opportunity for regulatory proteins to simultaneously control transcription initiation in both mtDNA strands.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.C116.727966