| 1997 |
POLRMT (h-mtRPOL) encodes the human mitochondrial RNA polymerase, a 1230 amino acid protein localized to mitochondria with sequence homology to mitochondrial RNA polymerases from lower eukaryotes and bacteriophage RNA polymerases; it carries out mitochondrial genome transcription and provides RNA primers for replication initiation. |
cDNA cloning, sequence analysis, chromosomal mapping (chromosome 19p13.3) |
Human molecular genetics |
Medium |
9097968
|
| 2015 |
MRPL12 (mitochondrial ribosomal protein L12) binds and stabilizes POLRMT; knockdown of MRPL12 by RNAi causes instability of POLRMT protein (but not other primary mitochondrial transcription components) and a corresponding decrease in mitochondrial transcription rates. MRPL10 knockdown selectively degrades the mature long form of MRPL12 without affecting POLRMT. |
RNAi knockdown, co-immunoprecipitation, mitochondrial transcription rate measurement, protein stability assays |
The Journal of biological chemistry |
Medium |
26586915
|
| 2017 |
POLRMT has high transcriptional fidelity (average error rate ~2×10⁻⁵), with a distinctly high propensity for GTP misincorporation opposite dT (~10⁻⁴). POLRMT also shows a high mutagenic bypass rate on 8-oxo-dG templates (~10⁻⁴ C→A error rate). TEFM increases the lifetime of POLRMT on terminally mismatched elongation substrates, allowing efficient bypass of errors and continuation of transcription. |
In vitro transcription fidelity assay measuring catalytic efficiencies of correct and incorrect nucleotide incorporation; kinetic analysis with and without TEFM |
The Journal of biological chemistry |
High |
28882896
|
| 2016 |
The G-quadruplex formed between nascent RNA and non-template DNA at conserved sequence block 2 (CSB2) of human mtDNA causes transcription termination by POLRMT in vitro; longer G-tracts at CSB2 correlate with increased termination. TEFM addition prevents termination at CSB2, acting as a rheostat for POLRMT activity at this site. |
In vitro transcription assay with CSB2 length variants, transcript 3'-end mapping, TEFM addition experiments |
Nucleic acids research |
High |
27436287
|
| 2018 |
TEFM enhances POLRMT transcription elongation by increasing stall force, reducing the frequency of long-lived pauses, and shortening pause durations, without changing pause-free elongation rate. POLRMT pausing dynamics at CSB2 are directly modulated by TEFM. |
Single-molecule optical tweezers transcription assay measuring real-time transcription dynamics, pause frequency, and pause duration with and without TEFM |
Biophysical journal |
High |
30514634
|
| 2021 |
Recessive and dominant variants in POLRMT cause defective mitochondrial mRNA synthesis in patient fibroblasts without mtDNA deletions or copy number changes; in vitro characterization of recombinant POLRMT mutants confirms variable but deleterious effects on mitochondrial transcription, establishing defective transcription as a disease mechanism. |
Patient fibroblast analysis, massive parallel sequencing, in vitro transcription assays with recombinant mutant POLRMT proteins |
Nature communications |
High |
33602924
|
| 2021 |
Knockout of POLRMT or TFB2M in human cybrid cells results in complete mtDNA loss, demonstrating that POLRMT is indispensable for maintenance of human mtDNA (required for priming of both strand-asynchronous and strand-coupled replication). |
CRISPR/Cas9 knockout of POLRMT and TFB2M in human cybrid cells, 2D agarose gel electrophoresis of replication intermediates, mtDNA quantification |
Biochimica et biophysica acta. Molecular cell research |
High |
34744028
|
| 2024 |
POLRMT is succinylated at lysine 622; this succinylation disrupts POLRMT interaction with mtDNA and mitochondrial transcription factors. SUCLG1 restricts succinyl-CoA levels to suppress POLRMT succinylation, thereby maintaining mtDNA transcription and mitochondrial biogenesis. |
Mass spectrometry identification of succinylation site, site-directed mutagenesis (K622), co-immunoprecipitation of POLRMT with mtDNA/transcription factors, SUCLG1 knockdown/overexpression, succinyl-CoA measurement, mouse and humanized leukemia models |
The EMBO journal |
High |
38649537
|
| 2025 |
POLRMT overexpression in mice increases mtDNA transcription initiation (elevated 7S RNA) but does not increase steady-state levels of mature mitochondrial mRNAs, indicating that post-transcriptional regulatory steps downstream of transcription initiation limit OXPHOS biogenesis. Simultaneous overexpression of POLRMT and LRPPRC also failed to increase mitochondrial transcript steady-state levels. |
Transgenic mouse overexpression model, RNA quantification (steady-state mRNA levels, 7S RNA), double overexpression with LRPPRC, exercise performance testing |
Life science alliance |
Medium |
41107062
|
| 2025 |
Nucleic acid sequence determinants of POLRMT transcriptional pausing were identified: a consensus pause motif 5'-R₋₁₀NNNNNNNGT₋₁G₊₁-3' (where -1 is the 3' nascent RNA nucleotide and +1 is the incoming NTP) causes strong pausing; multiple pause sites were mapped on human mtDNA. Most pause elements are shared with multisubunit prokaryotic and nuclear RNAPs despite structural differences. |
In vitro reconstitution of POLRMT transcription on nucleic acid scaffolds, systematic mutational analysis of pause sequences, mapping of pause sites on human mtDNA |
Biochemistry |
High |
40958658
|
| 2025 |
Cryo-EM structures of POLRMT transcription initiation complexes (IC3 and slipped-IC3) reveal: promoter melting begins at position −4 via base-specific interactions of −4 and −3 template guanines with POLRMT and −1 non-template adenine with TFB2M; de novo RNA synthesis begins at +1; RNA slippage occurs when synthesized 2-mer RNA shifts to −1; a non-template stabilizing loop (K153LDPRSGGVIKPP165) and Y209 from TFB2M and W1026 of POLRMT recognize the conserved non-template sequence (-1)AAA(+2). |
Cryo-EM structure determination of active initiation complexes; structural analysis of transcription bubble, start site selection, and slippage mechanism |
bioRxivpreprint |
High |
bio_10.1101_2024.12.02.626445
|
| 2025 |
Cryo-EM structures capturing POLRMT transitioning from open promoter complex to processive elongation complex reveal: TFAM-induced promoter bending creates a transcription-stimulatory interface between POLRMT and the upstream promoter region (UPR); UPR truncation reduces transcription from all mtDNA promoters, abolished by mutation of the POLRMT interface; the POLRMT tether helix mediates an autoinhibitory interaction with linear upstream DNA that enhances promoter specificity; deletion of the tether helix increases off-target transcription. |
Cryo-EM structural determination of multiple initiation complex conformations; mutational analysis of POLRMT-UPR interface and tether helix; in vitro transcription assays with truncated promoter templates |
bioRxivpreprint |
High |
bio_10.1101_2025.04.03.647028
|
| 2025 |
MD simulations indicate POLRMT translocation during elongation is coupled with NTP binding to enable fingers subdomain opening post-translocation; without NTP-coupled fingers opening, translocations proceed futilely. The coupled translocation time scale exceeds hundreds of microseconds, consistent with a postcatalytic kinetic step. This suggests a variation of Brownian ratcheting in POLRMT translocation distinct from bacteriophage T7 RNAP. |
All-atom molecular dynamics simulation of POLRMT elongation complexes, tICA and VAMPnet dimensional reduction analyses, comparison of pre- and post-translocation models |
Journal of chemical theory and computation |
Low |
40238747
|
| 2005 |
An alternative transcript of POLRMT containing 225 bp of intron 1 encodes a truncated protein lacking the mitochondrial targeting signal that localizes exclusively to the nucleus, proposed to correspond to nuclear RNA polymerase IV. |
RT-PCR detection of alternative transcripts in HeLa, mouse, and rat cells; sequence analysis of alternative exons; cellular localization inference from absence of mitochondrial targeting signal |
Molekuliarnaia biologiia |
Low |
15773549
|