Article Non-coding 7S RNA inhibits transcription via mitochondrial RNA polymerase dimerization

• Published in: Cell 2022, Vol.185 (13)
• Main Authors: Zhu, Xuefeng, Xie, Xie, Das, H., Tan, Benedict, Shi, Yonghong, Al-Behadili, Ali, Peter, Bradley, Motori, E., Valenzuela, Sebastian, Posse, Viktor, Gustafsson, Claes M, Hallberg, B. M., Falkenberg, Maria
• Format: Article
• Language: English
• Subjects: 6s rna; b2 rna; Biochemistry & Molecular Biology; Biochemistry and Molecular Biology; Biokemi och molekylärbiologi; Cell and Molecular Biology; Cell Biology; Cell- och molekylärbiologi; cryo-em; DNA-replication; double-stranded-rna; expression; identification; initiation; phosphorylase; polynucleotide; structural basis
• ISSN: 0092-8674
• DOI: 10.1016/j.cell.2022.05.006

The mitochondrial genome encodes 13 components of the oxidative phosphorylation system, and altered mitochondrial transcription drives various human pathologies. A polyadenylated, non-coding RNA molecule known as 7S RNA is transcribed from a region immediately downstream of the light strand promoter in mammalian cells, and its levels change rapidly in response to physiological conditions. Here, we report that 7S RNA has a regulatory function, as it controls levels of mitochondrial transcription both in vitro and in cultured human cells. Using cryo-EM, we show that POLRMT dimerization is induced by interactions with 7S RNA. The resulting POLRMT dimer interface sequesters domains necessary for promoter recognition and unwinding, thereby preventing transcription initiation. We propose that the non-coding 7S RNA molecule is a component of a negative feedback loop that regulates mitochondrial transcription in mammalian cells.