Chapter 22 In Vivo and In Vitro Approaches for Studying the Yeast Mitochondrial RNA Degradosome Complex

2008 ◽  
pp. 463-488 ◽  
Author(s):  
Michal Malecki ◽  
Robert Jedrzejczak ◽  
Olga Puchta ◽  
Piotr P. Stepien ◽  
Pawel Golik
Keyword(s):  
Mitochondrial Rna ◽  
Rna Degradosome

scholarly journals Interplay between substrate recognition, 5’ end tRNA processing and methylation activity of human mitochondrial RNase P

2018 ◽  
Author(s):  
Agnes Karasik ◽  
Carol A. Fierke ◽  
Markos Koutmos
Keyword(s):  
Mitochondrial Diseases ◽  
Protein S ◽  
Rnase P ◽  
Ribonuclease P ◽  
Mitochondrial Rna ◽  
P Protein ◽  
Adenosyl Methionine ◽  
Methylation Activity

ABSTRACTHuman mitochondrial ribonuclease P (mtRNase P) is an essential three protein complex that catalyzes the 5’ end maturation of mitochondrial precursor tRNAs (pre-tRNAs). MRPP3 (Mitochondrial RNase P Protein 3), a protein-only RNase P (PRORP), is the nuclease component of the mtRNase P complex and requires a two-protein S-adenosyl methionine (SAM)-dependent methyltransferase MRPP1/2 sub-complex to function. Dysfunction of mtRNase P is linked to several human mitochondrial diseases, such as mitochondrial myopathies. Despite its central role in mitochondrial RNA processing, little is known about how the protein subunits of mtRNase P function synergistically. Here we use purified mtRNase P to demonstrate that mtRNase P recognizes, cleaves, and methylates some, but not all, mitochondrial pre-tRNAs in vitro. Additionally, mtRNase P does not process all mitochondrial pre-tRNAs uniformly, suggesting the possibility that some pre-tRNAs require additional factors to be cleaved in vivo. Consistent with this, we found that addition of the MRPP1 co-factor SAM enhances the ability of mtRNase P to bind and cleave some mitochondrial pre-tRNAs. Furthermore, the presence of MRPP3 can enhance the methylation activity of MRPP1/2. Taken together, our data demonstrate that the subunits of mtRNase P work together to efficiently recognize, process and methylate human mitochondrial pre-tRNAs.

scholarly journals A tridecamer DNA sequence supports human mitochondrial RNA 3'-end formation in vitro.

1988 ◽  
Vol 8 (10) ◽  
pp. 4502-4509 ◽  
Author(s):  
T W Christianson ◽  
D A Clayton
Keyword(s):  
Dna Sequence ◽  
Transcription Termination ◽  
In Vitro Transcription ◽  
Mitochondrial Rna ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Transcription System ◽  
Flanking Regions

Vertebrate mitochondrial genomes contain a putative transcription termination site at the boundary between the genes for 16S rRNA and leucyl-tRNA. We have described previously an in vitro transcription system from human cells with the capacity to generate RNA 3' ends with the same map positions as those synthesized in vivo. By assaying the ability of variously truncated templates to support 3'-end formation, we demonstrated that the tridecamer sequence 5'-TGGCAGAGCCCCGG-3', contained entirely within the gene for leucyl-tRNA, is necessary to direct accurate termination. When two tridecamer sequences and their immediate flanking regions were placed in tandem, termination occurred at both promoter-proximal and promoter-distal sites. Furthermore, termination was competitively inhibited, in a concentration-dependent manner, by DNA containing the tridecamer sequence. These results suggest a modest sequence requirement for transcription termination that is contingent on a factor capable of recognizing the presence of the tridecamer DNA sequence.

A tridecamer DNA sequence supports human mitochondrial RNA 3'-end formation in vitro

1988 ◽  
Vol 8 (10) ◽  
pp. 4502-4509
Author(s):  
T W Christianson ◽  
D A Clayton
Keyword(s):  
Dna Sequence ◽  
Transcription Termination ◽  
In Vitro Transcription ◽  
Mitochondrial Rna ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Transcription System ◽  
Flanking Regions

Vertebrate mitochondrial genomes contain a putative transcription termination site at the boundary between the genes for 16S rRNA and leucyl-tRNA. We have described previously an in vitro transcription system from human cells with the capacity to generate RNA 3' ends with the same map positions as those synthesized in vivo. By assaying the ability of variously truncated templates to support 3'-end formation, we demonstrated that the tridecamer sequence 5'-TGGCAGAGCCCCGG-3', contained entirely within the gene for leucyl-tRNA, is necessary to direct accurate termination. When two tridecamer sequences and their immediate flanking regions were placed in tandem, termination occurred at both promoter-proximal and promoter-distal sites. Furthermore, termination was competitively inhibited, in a concentration-dependent manner, by DNA containing the tridecamer sequence. These results suggest a modest sequence requirement for transcription termination that is contingent on a factor capable of recognizing the presence of the tridecamer DNA sequence.

scholarly journals siRNAs containing 2′-fluorinated Northern-methanocarbacyclic (2′-F-NMC) nucleotides: in vitro and in vivo RNAi activity and inability of mitochondrial polymerases to incorporate 2′-F-NMC NTPs

2021 ◽  
Author(s):  
Masaaki Akabane-Nakata ◽  
Namrata D Erande ◽  
Pawan Kumar ◽  
Rohan Degaonkar ◽  
Jason A Gilbert ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Mitochondrial Rna ◽  
Seed Region ◽  
Guide Strand ◽  
Passenger Strand ◽  
Molecular Modeling Studies ◽  
Rnai Activity ◽  
Rna And Dna

Abstract We recently reported the synthesis of 2′-fluorinated Northern-methanocarbacyclic (2′-F-NMC) nucleotides, which are based on a bicyclo[3.1.0]hexane scaffold. Here, we analyzed RNAi-mediated gene silencing activity in cell culture and demonstrated that a single incorporation of 2′-F-NMC within the guide or passenger strand of the tri-N-acetylgalactosamine-conjugated siRNA targeting mouse Ttr was generally well tolerated. Exceptions were incorporation of 2′-F-NMC into the guide strand at positions 1 and 2, which resulted in a loss of the in vitro activity. Activity at position 1 was recovered when the guide strand was modified with a 5′ phosphate, suggesting that the 2′-F-NMC is a poor substrate for 5′ kinases. In mice, the 2′-F-NMC-modified siRNAs had comparable RNAi potencies to the parent siRNA. 2′-F-NMC residues in the guide seed region position 7 and at positions 10, 11 and 12 were well tolerated. Surprisingly, when the 5′-phosphate mimic 5′-(E)-vinylphosphonate was attached to the 2′-F-NMC at the position 1 of the guide strand, activity was considerably reduced. The steric constraints of the bicyclic 2′-F-NMC may impair formation of hydrogen-bonding interactions between the vinylphosphonate and the MID domain of Ago2. Molecular modeling studies explain the position- and conformation-dependent RNAi-mediated gene silencing activity of 2′-F-NMC. Finally, the 5′-triphosphate of 2′-F-NMC is not a substrate for mitochondrial RNA and DNA polymerases, indicating that metabolites should not be toxic.

scholarly journals The pentatricopeptide repeat protein Rmd9 recognizes the dodecameric element in the 3′-UTRs of yeast mitochondrial mRNAs

2021 ◽  
Vol 118 (15) ◽  
pp. e2009329118
Author(s):  
Hauke S. Hillen ◽  
Dmitriy A. Markov ◽  
Ireneusz D. Wojtas ◽  
Katharina B. Hofmann ◽  
Michael Lidschreiber ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Rna Stability ◽  
Mitochondrial Rna ◽  
Pentatricopeptide Repeat ◽  
Sequence Element ◽  
Posttranscriptional Gene Regulation ◽  
The Family ◽  
Ppr Proteins

Stabilization of messenger RNA is an important step in posttranscriptional gene regulation. In the nucleus and cytoplasm of eukaryotic cells it is generally achieved by 5′ capping and 3′ polyadenylation, whereas additional mechanisms exist in bacteria and organelles. The mitochondrial mRNAs in the yeast Saccharomyces cerevisiae comprise a dodecamer sequence element that confers RNA stability and 3′-end processing via an unknown mechanism. Here, we isolated the protein that binds the dodecamer and identified it as Rmd9, a factor that is known to stabilize yeast mitochondrial RNA. We show that Rmd9 associates with mRNA around dodecamer elements in vivo and that recombinant Rmd9 specifically binds the element in vitro. The crystal structure of Rmd9 bound to its dodecamer target reveals that Rmd9 belongs to the family of pentatricopeptide (PPR) proteins and uses a previously unobserved mode of specific RNA recognition. Rmd9 protects RNA from degradation by the mitochondrial 3′-exoribonuclease complex mtEXO in vitro, indicating that recognition and binding of the dodecamer element by Rmd9 confers stability to yeast mitochondrial mRNAs.

scholarly journals The human mitochondrial 12S rRNA m4C methyltransferase METTL15 is required for proper mitochondrial function

2019 ◽  
Author(s):  
Hao Chen ◽  
Zhennan Shi ◽  
Jiaojiao Guo ◽  
Kao-jung Chang ◽  
Qianqian Chen ◽  
...  
Keyword(s):  
Mitochondrial Protein ◽  
Small Subunit ◽  
12S Rrna ◽  
Mitochondrial Rna ◽  
Protein Coding ◽  
Mitochondrial Ribosome ◽  
The Difference ◽  
And Function

ABSTRACTMitochondrial DNA (mtDNA) gene expression is coordinately regulated pre- and post-transcriptionally, and its perturbation can lead to human pathologies. Mitochondrial ribosomal RNAs (mt-rRNAs) undergo a series of nucleotide modifications following release from polycistronic mitochondrial RNA (mtRNA) precursors, which is essential for mitochondrial ribosomal biogenesis. Cytosine N4 methylation (m4C) at position 839 of the 12S small subunit (SSU) mt-rRNA was identified decades ago, however, its biogenesis and function have not been elucidated in details. Here we demonstrate that human Methyltransferase Like 15 (METTL15) is responsible for 12S mt-rRNA methylation at C839 (m4C839) both in vivo and in vitro. We tracked the evolutionary history of RNA m4C methyltransferases and revealed the difference in substrates preference between METTL15 and its bacterial ortholog rsmH. Additionally, unlike the very modest impact on ribosome upon loss of m4C methylation in bacterial SSU rRNA, we found that depletion of METTL15 specifically causes severe defects in mitochondrial ribosome assembly, which leads to an impaired translation of mitochondrial protein-coding genes and a decreased mitochondrial respiration capacity. Our findings point to a co-evolution of methylatransferase specificities and modification patterns in rRNA with differential impact on prokaryotic ribosome versus eukaryotic mitochondrial ribosome.

scholarly journals Inactivation of the tumor suppressor p53 by long noncoding RNA RMRP

2021 ◽  
Vol 118 (29) ◽  
pp. e2026813118
Author(s):  
Yajie Chen ◽  
Qian Hao ◽  
Shanshan Wang ◽  
Mingming Cao ◽  
Yingdan Huang ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Long Noncoding Rna ◽  
Noncoding Rna ◽  
Parp Inhibitors ◽  
Parp Inhibition ◽  
Mitochondrial Rna ◽  
Tumor Resistance ◽  
Factor C

p53 inactivation is highly associated with tumorigenesis and drug resistance. Here, we identify a long noncoding RNA, the RNA component of mitochondrial RNA-processing endoribonuclease (RMRP), as an inhibitor of p53. RMRP is overexpressed and associated with an unfavorable prognosis in colorectal cancer. Ectopic RMRP suppresses p53 activity by promoting MDM2-induced p53 ubiquitination and degradation, while depletion of RMRP activates the p53 pathway. RMRP also promotes colorectal cancer growth and proliferation in a p53-dependent fashion in vitro and in vivo. This anti-p53 action of RMRP is executed through an identified partner protein, SNRPA1. RMRP can interact with SNRPA1 and sequester it in the nucleus, consequently blocking its lysosomal proteolysis via chaperone-mediated autophagy. The nuclear SNRPA1 then interacts with p53 and enhances MDM2-induced proteasomal degradation of p53. Remarkably, ablation of SNRPA1 completely abrogates RMRP regulation of p53 and tumor cell growth, indicating that SNRPA1 is indispensable for the anti-p53 function of RMRP. Interestingly and significantly, poly (ADP-ribose) polymerase (PARP) inhibitors induce RMRP expression through the transcription factor C/EBPβ, and RMRP confers tumor resistance to PARP inhibition by preventing p53 activation. Altogether, our study demonstrates that RMRP plays an oncogenic role by inactivating p53 via SNRPA1 in colorectal cancer.

Accurate in vitro transcription of Xenopus laevis mitochondrial DNA from two bidirectional promoters

1986 ◽  
Vol 6 (7) ◽  
pp. 2543-2550
Author(s):  
D F Bogenhagen ◽  
B K Yoza
Keyword(s):  
Mitochondrial Dna ◽  
Xenopus Laevis ◽  
Rna Polymerase ◽  
Consensus Sequence ◽  
In Vitro Transcription ◽  
Xenopus Laevis Oocytes ◽  
Mitochondrial Rna ◽  
Bidirectional Promoters

The mitochondrial RNA polymerase from Xenopus laevis oocytes was partially purified by heparin-Sepharose chromatography and phosphocellulose chromatography. This RNA polymerase preparation specifically initiated the transcription of X. laevis mitochondrial DNA (mtDNA) from two bidirectional promoters contained within a 123-base-pair segment of the mtDNA between the heavy-strand replication origin and the rRNA cistrons. Transcription in vitro initiated from precisely the same start sites previously mapped as initiation sites for transcription in vivo. At each of the four sites, initiation occurred within a conserved nucleotide sequence, ACPuTTATA. This consensus sequence is not related to promoters for transcription of human mtDNA.

scholarly journals An Arginine-Glycine-Rich RNA Binding Protein Impacts the Abundance of Specific mRNAs in the Mitochondria of Trypanosoma brucei

2014 ◽  
Vol 14 (2) ◽  
pp. 149-157 ◽  
Author(s):  
Natalie M. McAdams ◽  
Michelle L. Ammerman ◽  
Julee Nanduri ◽  
Kaylen Lott ◽  
John C. Fisk ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
Rna Editing ◽  
Rna Binding ◽  
Mitochondrial Gene ◽  
Mitochondrial Rna ◽  
Insect Vector ◽  
Sequence Specificity ◽  
Content Type

ABSTRACT In kinetoplastid parasites, regulation of mitochondrial gene expression occurs posttranscriptionally via RNA stability and RNA editing. In addition to the 20S editosome that contains the enzymes required for RNA editing, a dynamic complex called the mitochondrial RNA binding 1 (MRB1) complex is also essential for editing. Trypanosoma brucei RGG3 (TbRGG3) was originally identified through its interaction with the guide RNA-associated proteins 1 and 2 (GAP1/2), components of the MRB1 complex. Both the arginine-glycine-rich character of TbRGG3, which suggests a function in RNA binding, and its interaction with MRB1 implicate TbRGG3 in mitochondrial gene regulation. Here, we report an in vitro and in vivo characterization of TbRGG3 function in T. brucei mitochondria. We show that in vitro TbRGG3 binds RNA with broad sequence specificity and has the capacity to modulate RNA-RNA interactions. In vivo , inducible RNA interference (RNAi) studies demonstrate that TbRGG3 is essential for proliferation of insect vector stage T. brucei . TbRGG3 ablation does not cause a defect in RNA editing but, rather, specifically affects the abundance of two preedited transcripts as well as their edited counterparts. Protein-protein interaction studies show that TbRGG3 associates with GAP1/2 apart from the remainder of the MRB1 complex, as well as with several non-MRB1 proteins that are required for mitochondrial RNA editing and/or stability. Together, these studies demonstrate that TbRGG3 is an essential mitochondrial gene regulatory factor that impacts the stabilities of specific RNAs.

scholarly journals Anti-viral nucleotide incorporation by recombinant human mitochondrial RNA polymerase is predictive for increased in vivo mitochondrial toxicity risk

2016 ◽  
pp. AAC.01253-16 ◽  
Author(s):  
Martijn Fenaux ◽  
Xiaodong Lin ◽  
Fumiaki Yokokawa ◽  
Zachary Sweeney ◽  
Oliver Saunders ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Mitochondrial Dysfunction ◽  
Elevated Serum ◽  
Nucleoside Analogs ◽  
Hepatic Function ◽  
Gene Signature ◽  
Mitochondrial Rna ◽  
Mitochondrial Rna Polymerase

Nucleoside or nucleotide inhibitors are a highly successful class of antivirals due to selectivity, potency, broad coverage, and high barrier to resistance. Nucleosides are the backbone of combination treatments for HIV, hepatitis B and - since the FDA approval of sofosbuvir in 2013 - also for hepatitis C (HCV). However, many promising nucleotides have advanced to clinical trials only to be terminated due to unexpected toxicity. Here we describe the in vitro pharmacology of1, a monophosphate prodrug of a 2’ -ethynyluridine developed for the treatment of HCV.1inhibits multiple HCV genotypes in vitro (EC50= 0.05-0.1 μM) with a selectivity index of >300 (CC50= 30 μM in MT-4 cells). The active triphosphate metabolite of1,2, does not inhibit human α, β or γ DNA polymerases, but was a substrate for incorporation by the human mitochondrial RNA polymerase (POLRMT). In dog, the oral administration of1resulted in elevated serum liver enzymes and microscopic changes in the liver. Transmission electron microscopy showed significant mitochondrial swelling and lipid accumulation in hepatocytes. Gene expression analysis revealed dose-proportional gene signature changes linked to loss of hepatic function and increased mitochondrial dysfunction. The potential of in vivo toxicity through mitochondrial polymerase incorporation by nucleoside analogs has been previously shown. This study shows that even moderate levels of nucleotide analog incorporation by POLRMT increase the risk of in vivo mitochondrial dysfunction. Based on these results, further development of1as an anti-HCV compound was terminated.

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