A model for transcription initiation in human mitochondria.
Bottom Line: In this study we mapped the binding sites of the core transcription initiation factors TFAM and TFB2M on human mitochondrial RNA polymerase, and interactions of the latter with promoter DNA.This allowed us to construct a detailed structural model, which displays a remarkable level of interaction between the components of the initiation complex (IC).The architecture of the mitochondrial IC suggests mechanisms of promoter binding and recognition that are distinct from the mechanisms found in RNAPs operating in all domains of life, and illuminates strategies of transcription regulation developed at the very early stages of evolution of gene expression.
Affiliation: Department of Cell Biology, School of Osteopathic Medicine, Rowan University, 2 Medical Center Dr., Stratford, NJ 08084, USA.Show MeSH
Mentions: Using chemical mapping with CNBr under ‘single hit’ (19,20) conditions, we mapped the region in TFB2M that interacts with mtRNAP to the interval flanked by residues 315–352 (Figure 2A and Supplementary Figure S3). This region corresponds to the α8 helix in the model of TFB2M, which was built based on the structure of its homolog, TFB1M (21) (Figure 2B). Despite a relatively low-sequence conservation between TFB1M (which is not a transcription factor) and yeast homolog of TFB2M, Mtf1 (transcription factor) these proteins exhibit high structural conservation (21,22). The very N-terminal domain of TFB2M (res 1–69) is implicated in DNA binding and interaction with the priming ATP (15), however, does not share any sequence homology with TFB1M and is illustrated as a dashed line in this model (Figure 2B).
Affiliation: Department of Cell Biology, School of Osteopathic Medicine, Rowan University, 2 Medical Center Dr., Stratford, NJ 08084, USA.