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Characterization of the basic transcription machinery of mammalian mitochondrial DNA has been greatly supported by the availability
of pure recombinant mitochondrial RNA polymerase (mtRNAP) and accessory factors, which allowed to develop a reconstituted
in vitro transcription system. This chapter outlines a general strategy that makes use of a minimal promoter-independent transcription
assay to study mitochondrial transcription termination in animal systems. We used such a system to investigate the transcription
termination properties of the sea urchin factor mtDBP, however, it is applicable to the study of transcription termination
in a variety of organisms, provided that the pure mtRNAP and the transcription termination factor are available.
The assay here described contains the recombinant proteins mtRNAP and mtDBP, both expressed in insect cells, and a template
consisting of a 3′-tailed DNA construct bearing the sequence bound by mtDBP. Transcription by the RNA polymerase produces
run-off and terminated molecules, the size of the latter being consistent with RNA chain arrest in correspondence of the mtDBP–DNA
complex. Transcription termination is protein-dependent as addition of increasing amounts of mtDBP to the assay causes a decrease
in the intensity of the run-off and the gradual appearance of short-terminated molecules. Furthermore, we report a method,
based on pulse-chase experiments, which allows us to distinguish between the true termination and the pausing events.
Affiliation(s): (2) Dipartimento di Biochimica e Biologia Molecolare “Ernesto Quagliariello”, Università degli Studi di Bari, Bari, Italy
Book Title: Mitochondrial DNA: Methods and Protocols
Series: Methods in Molecular Biology | Volume: 554 | Pub. Date: Sep-01-2009 | Page Range: 127-141 | DOI: 10.1007/978-1-59745-521-3_9
Subject: Cell Biology
Key Words: Transcription factors - transcription termination - sea urchin mtDBP - mtRNA polymerase - termination assay - pulse-chase experiment
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