mitochondrial DNA-directed RNA polymerase complex

Definition

Target type: cellularcomponent

A DNA-directed RNA polymerase complex located in the mitochondrion. Mitochondrial RNA polymerase is composed of two subunits, a catalytic core, which resembles the enzymes from bacteriophage T7 and T3, and a specificity factor required for promoter recognition, which is similar to members of the eubacterial sigma factor family. In S. cerevisiae, these are encoded by the nuclear genes RPO41 and MTF1 and the specificity factor, required for promoter recognition and initiation, is not present in the elongating form. [GOC:krc, GOC:mah, PMID:7929382]

The mitochondrial DNA-directed RNA polymerase complex is a multi-protein assembly responsible for transcribing mitochondrial DNA (mtDNA) into mitochondrial RNA. This complex is essential for the production of proteins involved in oxidative phosphorylation, a process that generates ATP, the primary energy source for cells.

The complex consists of several core subunits:

* **Mitochondrial RNA polymerase (POLRMT):** The catalytic subunit responsible for synthesizing RNA from a DNA template. It is a single-subunit polymerase with a structure similar to bacterial RNA polymerases.
* **Mitochondrial transcription factor A (TFAM):** A DNA-binding protein that binds to mtDNA and promotes the assembly of the transcription complex. It helps to unwind and melt the DNA double helix, making it accessible to POLRMT.
* **Mitochondrial transcription factor B1 (TFB1M):** A transcription factor that interacts with POLRMT and TFAM. It stabilizes the transcription complex and promotes the initiation of transcription.
* **Mitochondrial transcription factor B2 (TFB2M):** Another transcription factor that interacts with POLRMT and TFAM. It plays a role in regulating the elongation of transcription.

In addition to these core subunits, the complex may also include other proteins, such as:

* **Mitochondrial transcription factor D (TFDM):** A protein that interacts with TFAM and may contribute to the regulation of transcription.
* **Mitochondrial transcription factor E (TFEM):** A protein that has been implicated in the processing of mitochondrial RNA.

The complex assembles on mtDNA at specific promoter regions, which are located upstream of the genes that need to be transcribed. The complex then initiates transcription by separating the two strands of mtDNA and using the template strand to synthesize a complementary RNA molecule.

Transcription proceeds along the mtDNA, and the newly synthesized RNA molecule is processed and transported to the cytoplasm where it is translated into proteins.

The mitochondrial DNA-directed RNA polymerase complex is essential for the production of mitochondrial proteins. These proteins are crucial for the function of the mitochondria, which are the powerhouses of cells. Defects in the complex can lead to mitochondrial dysfunction and a variety of human diseases.'
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Proteins (1)

Compounds (1)