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Diverse topological requirements for mitochondrial transcription (573.5)
Author(s) -
Sondheimer Neal,
Zollo Ornella
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.573.5
Subject(s) - tfam , promoter , mitochondrial dna , transcription factor , transcription (linguistics) , biology , response element , general transcription factor , microbiology and biotechnology , genetics , topology (electrical circuits) , gene , computational biology , gene expression , mathematics , linguistics , philosophy , combinatorics
That transcription of the three human mitochondrial promoters can be recapitulated in vitro using a limited set of proteins including the mitochondrial RNA polymerase (POLRMT) and two accessory factors, mitochondrial transcription factor A (TFAM) and transcription factor B2 (TFB2M). The complete set of mechanisms that regulate promoter selection are unknown. The objective of this study was to determine whether the topological state of template DNA plays a role in promoter selection. We used a plasmid‐based system for the in vitro analysis of transcription that recapitulates features of the mtDNA to illustrate the relationship between topology and the three mitochondrial promoters and the involvement of TFAM which can bend template DNA. Both heavy‐strand promoters (HSP1 and HSP2) can be simultaneously transcribed from a circular template but increasing TFAM concentrations suppress HSP2 transcription at concentrations that result in HSP1 activation. We identified a requirement for the use of supercoiled DNA at HSP2 for transcription from circular templates which is not present for HSP1 and LSP. We conclude that the mitochondrial promoters have distinct requirements for DNA topology and TFAM dosage in vitro providing a means for the differential regulation of mitochondrial gene expression. Grant Funding Source : NIH/NICHD