In Vitro Transcription of Xenopus Mitochondrial Deoxyribonucleic Acid by Homologous Mitochondrial Ribonucleic Acid Polymerase
Year: 1974
Type: article
Abstract: The transcription in vitro of mitochondrial DNA by mitochondrial RNA polymerase from Xenopus laevis has been studied. Nearest neighbor frequencies of the transcribed RNA showed only small deviations from a random pattern. Nascent RNA is bound to the template such that 25 to 35% of the RNA is in a state protected from digestion with ribonuclease. The RNA sediments between 4 and 12 S in sucrose gradients after its release from the template. Mitochondrial RNA polymerase transcribes mtDNA with considerable strand selectivity. With mtDNA-I (closed circular DNA) the heavy (H) strand is preferred about 3:1. With mtDNA-II (nicked circular DNA) the H strand is preferred 20:1. In contrast, denatured mtDNA is transcribed with a 5:1 preference for the light (L) strand. Study of the inhibition of enzyme activity by the rifamycin derivative AF/ABDP suggests that the chain initiation step is more sensitive to the inhibitor than the elongation step. RNA chain initiation in vitro was studied with γ-32P-ribonucleoside triphosphates. Mitochondrial RNA polymerase initiates on mtDNA predominantly with ATP, 2-fold less frequently with GTP, and rarely if at all with the pyrimidine ribonucleoside triphosphates. In pancreatic RNase digests of terminally labeled RNA, at least three but probably many 32P-labeled oligonucleotides were observed, suggesting that in vitro chain initiation occurred at a number of sites on the template.
Source: Journal of Biological Chemistry
Authors: Guang-Jer Wu, Igor B. Dawid
Institutions: Carnegie Institution for Science, Department of Embryology
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1588631590