transcription initiation at mitochondrial promoter

Definition

Target type: biologicalprocess

A transcription initiation process that takes place at a promoter on the mitochondrial chromosome. [PMID:33127643]

Transcription initiation at mitochondrial promoters is a complex process that involves the assembly of a multi-protein complex at the promoter region of the mitochondrial DNA. This complex includes the mitochondrial RNA polymerase (mtRNAP), transcription factors (TFAM and TFB2M), and other factors involved in DNA unwinding and stabilization. The process can be divided into several steps:

1. **TFAM binding:** TFAM, a high-mobility group (HMG)-box containing protein, binds to the promoter region of the mitochondrial DNA. TFAM is essential for DNA unwinding and for recruiting mtRNAP to the promoter.
2. **TFB2M binding:** TFB2M, a single-stranded DNA binding protein, binds to the promoter region downstream of TFAM. It helps to stabilize the unwound DNA and facilitates the binding of mtRNAP.
3. **mtRNAP binding:** mtRNAP, a unique DNA-dependent RNA polymerase specific to mitochondria, binds to the promoter region in a complex with TFAM and TFB2M. This complex, known as the pre-initiation complex, is crucial for initiating transcription.
4. **DNA unwinding:** Once the pre-initiation complex is assembled, mtRNAP initiates the unwinding of the DNA duplex at the promoter region, exposing the template strand for transcription.
5. **RNA synthesis:** mtRNAP then starts synthesizing RNA using the unwound template strand as a guide. The process of RNA synthesis involves adding nucleotides complementary to the template strand one by one, extending the nascent RNA chain.
6. **Transcription termination:** Transcription termination occurs when mtRNAP encounters a specific termination signal within the mitochondrial DNA sequence. This signal triggers the release of the newly synthesized RNA molecule from mtRNAP.

The efficiency of transcription initiation is influenced by factors such as the sequence of the promoter region, the availability of transcription factors, and the cellular metabolic state. Transcription at mitochondrial promoters is highly regulated, ensuring that the synthesis of mitochondrial RNAs is coordinated with the cellular energy demands.'
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Proteins (1)

Compounds (1)