D-MTERF5 is a novel factor modulating transcription in Drosophila mitochondria

Abstract

The MTERF protein family comprises members from Metazoans and plants. All the Metazoan MTERF proteins characterized to date, including the mitochondrial transcription termination factors, play a key role in mitochondrial gene expression. In this study we report the characterization of Drosophila MTERF5 (D-MTERF5), a mitochondrial protein existing only in insects, probably originated from a duplication event of the transcription termination factor DmTTF. D-MTERF5 knock-down in D.Mel-2 cells alters transcript levels with an opposite pattern to that produced by DmTTF knock-down. D-MTERF5 is able to interact with mtDNA at the same sites contacted by DmTTF, but only in the presence of the termination factor. We propose that the two proteins participate in the transcription termination process, with D-MTERF5 engaged in relieving the block exerted by DmTTF. This hypothesis is supported also by D-MTERF5 homology modeling, which suggests that this protein contains protein–protein interaction domains. Co-regulation by DREF (DNA Replication-related Element binding Factor) of D-MTERF5 and DmTTF implies that expression of the two factors needs to be co-ordinated to ensure fine modulation of Drosophila mitochondrial transcription.

MTERF4 regulates the mitochondrial dysfunction induced by MPP+ in SH-SY5Y cells

“…After 24 h, the cells were fixed with 3.7% paraformaldehyde for 20 min, permeabilized with 0.2% Triton X-100 for 10 min, and blocked with 5% BSA in 37 C for 30 min. Then, the cells were incubated with mouse monoclonal anti-COX IV (Abcam, 1:200) and rabbit monoclonal anti-MTERF4 antibody (Abcam, 1:200) at 37 C for 2 h. Next, the cells were incubated with Alexa Fluor 488 conjugated anti-mouse antibody and Alexa Fluor 595 conjugated anti-rabbit antibody as previously described [21]. The images were captured with a fluorescent inverted microscope (Leica DM IL LED).…”

Mitochondrial Transcription Terminator Family Members mTTF and mTerf5 Have Opposing Roles in Coordination of mtDNA Synthesis

“…The amount and activity of mTTF therefore influences the steady-state levels of mitochondrial RNAs whose coding sequences lie between the mTTF binding sites and the putative promoters [52]. Knockdown of an insect-specific paralog of mTTF, mTerf5 (CG7175), was found to have opposite effects on transcript levels to knockdown of mTTF, despite the fact that mTerf5 binds to the same sites in mtDNA in an mTTF-dependent manner [54].…”

Drosophila nuclear factor DREF regulates the expression of the mitochondrial DNA helicase and mitochondrial transcription factor B2 but not the mitochondrial translation factor B1

“…Previous studies have shown that DREF controls the expression of d-mtssb [16], d-pol γ-β [12], d-tfam [17], d-mTTF [18] and d-MTERF5 [19], but not that of d-pol γ-α [12] or d-mtRNA polymerase [18]. In this study, we conclude that every known component of the Drosophila mtDNA replication and transcription machinery is regulated by DREF, except for the catalytic core of the mitochondrial DNA polymerase ( pol γ-α ) and mtRNA polymerase ; this likely results in regulation of their enzymatic activities solely at the level of nucleotide polymerization.…”

“…It can function as a traditional transcription factor, when DREs are located several hundred base pairs upstream of the transcriptional start site [10], or as part of the basal transcriptional machinery in which, together with TRF2 (TBP Related Factor 2 in Drosophila ), it may function as a promoter selectivity factor [15]. Interestingly, DREF also controls the expression of several genes involved in mtDNA replication and transcription: d-mtssb (mitochondrial single-stranded DNA-binding protein) [16], d-pol γ-β (the accessory-subunit of the mitochondrial DNA polymerase) [12], d-tfam (mitochondrial transcription factor A) [17], d-mTTF (the mitochondrial transcription termination factor) [18] and d-MTERF5 (an insect-specific factor also acting in transcription termination) [19], thus providing evidence for a coordinated genetic regulation of nuclear DNA replication, and therefore cell cycle progression and cell proliferation, and mitochondrial DNA metabolism.…”