Revealing the mechanism of directional transcription termination at the single molecule level for the human mitochondrial transcription complex

• Applicant: Dr. David Dulin, Ph.D.
• Subject Area: Biophysics ; Biochemistry
• Term: from 2020 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 436178547

Transcription termination is an essential cellular process to generate a functional transcriptome, e.g. full length RNA’s as encoded in the genome, and to recycle transcribing RNAP at the end of genes. Transcription termination is a difficult task though, as – once in elongation – cellular RNA polymerases (RNAP) form a very stable complex with DNA, capable of synthesizing kilobases long RNA’s. Therefore cells have developed several strategies to efficiently terminate and recycle RNAP’s at the end of transcribed genes. One of these strategies uses a protein termination factor bound to a specific termination site, as for Pol I and the human mitochondrial RNAP (mtRNAP). Interestingly, Pol I and mtRNAP are terminated directionally, i.e. only the transcription of one of the strands leads to termination upon collision with the termination factor. Despite their importance, the mechanism by which these termination factors sense the direction of transcribing Pol I and mtRNAP is unknown. As being the powerhouse of the eukaryotic cell, mitochondria are therefore essential for cell homeostasis, and the expression and maintenance of mitochondrial genome is of central importance. Here, I propose to uncover how the termination factor MTERF1 senses and terminates transcribing mtRNAP from only one direction. To reveal this mechanism, I will use single molecule biophysics techniques, as they are uniquely fitted to interrogate intrinsically heterogeneous enzymatic reactions, such as transcription, and enable the spatial and force manipulation of biomolecules. The findings of the present proposal will provide the complete mechanochemistry of directional transcription termination induced by a termination factor and pave the way for future studies of human mitochondria transcription regulation.

• DFG Programme: Research Grants
• International Connection: Netherlands