Mitochondrial Gene Expression in Yeast: Further Studies of a Self-Splicing Group II Intron

Author(s):  
Philip S. Perlman ◽  
Kevin A. Jarrell ◽  
Rosemary C. Dietrich ◽  
Craig L. Peebles ◽  
Steven L. Romiti ◽  
...  
2021 ◽  
Vol 22 (11) ◽  
pp. 6054
Author(s):  
Ioanna Kokkinopoulou ◽  
Paraskevi Moutsatsou

Mitochondria are membrane organelles present in almost all eukaryotic cells. In addition to their well-known role in energy production, mitochondria regulate central cellular processes, including calcium homeostasis, Reactive Oxygen Species (ROS) generation, cell death, thermogenesis, and biosynthesis of lipids, nucleic acids, and steroid hormones. Glucocorticoids (GCs) regulate the mitochondrially encoded oxidative phosphorylation gene expression and mitochondrial energy metabolism. The identification of Glucocorticoid Response Elements (GREs) in mitochondrial sequences and the detection of Glucocorticoid Receptor (GR) in mitochondria of different cell types gave support to hypothesis that mitochondrial GR directly regulates mitochondrial gene expression. Numerous studies have revealed changes in mitochondrial gene expression alongside with GR import/export in mitochondria, confirming the direct effects of GCs on mitochondrial genome. Further evidence has made clear that mitochondrial GR is involved in mitochondrial function and apoptosis-mediated processes, through interacting or altering the distribution of Bcl2 family members. Even though its exact translocation mechanisms remain unknown, data have shown that GR chaperones (Hsp70/90, Bag-1, FKBP51), the anti-apoptotic protein Bcl-2, the HDAC6- mediated deacetylation and the outer mitochondrial translocation complexes (Tom complexes) co-ordinate GR mitochondrial trafficking. A role of mitochondrial GR in stress and depression as well as in lung and hepatic inflammation has also been demonstrated.


2021 ◽  
Vol 22 (5) ◽  
pp. 2746
Author(s):  
Dimitri Shcherbakov ◽  
Reda Juskeviciene ◽  
Adrián Cortés Sanchón ◽  
Margarita Brilkova ◽  
Hubert Rehrauer ◽  
...  

Mitochondrial misreading, conferred by mutation V338Y in mitoribosomal protein Mrps5, in-vivo is associated with a subtle neurological phenotype. Brain mitochondria of homozygous knock-in mutant Mrps5V338Y/V338Y mice show decreased oxygen consumption and reduced ATP levels. Using a combination of unbiased RNA-Seq with untargeted metabolomics, we here demonstrate a concerted response, which alleviates the impaired functionality of OXPHOS complexes in Mrps5 mutant mice. This concerted response mitigates the age-associated decline in mitochondrial gene expression and compensates for impaired respiration by transcriptional upregulation of OXPHOS components together with anaplerotic replenishment of the TCA cycle (pyruvate, 2-ketoglutarate).


1986 ◽  
Vol 261 (1) ◽  
pp. 376-380 ◽  
Author(s):  
R S Williams ◽  
S Salmons ◽  
E A Newsholme ◽  
R E Kaufman ◽  
J Mellor

Mobile DNA ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Justin M. Waldern ◽  
Dorie Smith ◽  
Carol Lyn Piazza ◽  
E. Jake Bailey ◽  
Nicholas J. Schiraldi ◽  
...  

Abstract Background Group II introns are mobile retroelements, capable of invading new sites in DNA. They are self-splicing ribozymes that complex with an intron-encoded protein to form a ribonucleoprotein that targets DNA after splicing. These molecules can invade DNA site-specifically, through a process known as retrohoming, or can invade ectopic sites through retrotransposition. Retrotransposition, in particular, can be strongly influenced by both environmental and cellular factors. Results To investigate host factors that influence retrotransposition, we performed random insertional mutagenesis using the ISS1 transposon to generate a library of over 1000 mutants in Lactococcus lactis, the native host of the Ll.LtrB group II intron. By screening this library, we identified 92 mutants with increased retrotransposition frequencies (RTP-ups). We found that mutations in amino acid transport and metabolism tended to have increased retrotransposition frequencies. We further explored a subset of these RTP-up mutants, the most striking of which is a mutant in the ribosomal RNA methyltransferase rlmH, which exhibited a reproducible 20-fold increase in retrotransposition frequency. In vitro and in vivo experiments revealed that ribosomes in the rlmH mutant were defective in the m3Ψ modification and exhibited reduced binding to the intron RNA. Conclusions Taken together, our results reinforce the importance of the native host organism in regulating group II intron retrotransposition. In particular, the evidence from the rlmH mutant suggests a role for ribosome modification in limiting rampant retrotransposition.


2019 ◽  
Vol 47 (14) ◽  
pp. 7502-7517 ◽  
Author(s):  
Anna V Kotrys ◽  
Dominik Cysewski ◽  
Sylwia D Czarnomska ◽  
Zbigniew Pietras ◽  
Lukasz S Borowski ◽  
...  

AbstractMaintenance of mitochondrial gene expression is crucial for cellular homeostasis. Stress conditions may lead to a temporary reduction of mitochondrial genome copy number, raising the risk of insufficient expression of mitochondrial encoded genes. Little is known how compensatory mechanisms operate to maintain proper mitochondrial transcripts levels upon disturbed transcription and which proteins are involved in them. Here we performed a quantitative proteomic screen to search for proteins that sustain expression of mtDNA under stress conditions. Analysis of stress-induced changes of the human mitochondrial proteome led to the identification of several proteins with poorly defined functions among which we focused on C6orf203, which we named MTRES1 (Mitochondrial Transcription Rescue Factor 1). We found that the level of MTRES1 is elevated in cells under stress and we show that this upregulation of MTRES1 prevents mitochondrial transcript loss under perturbed mitochondrial gene expression. This protective effect depends on the RNA binding activity of MTRES1. Functional analysis revealed that MTRES1 associates with mitochondrial RNA polymerase POLRMT and acts by increasing mitochondrial transcription, without changing the stability of mitochondrial RNAs. We propose that MTRES1 is an example of a protein that protects the cell from mitochondrial RNA loss during stress.


1988 ◽  
Vol 8 (6) ◽  
pp. 2361-2366 ◽  
Author(s):  
K A Jarrell ◽  
R C Dietrich ◽  
P S Perlman

A self-splicing group II intron of yeast mitochondrial DNA (aI5g) was divided within intron domain 4 to yield two RNAs that trans-spliced in vitro with associated trans-branching of excised intron fragments. Reformation of the domain 4 secondary structure was not necessary for the trans reaction, since domain 4 sequences were shown to be dispensable. Instead, the trans reaction depended on a previously unpredicted interaction between intron domain 5, the most highly conserved region of group II introns, and another region of the RNA. Domain 5 was shown to be essential for cleavage at the 5' splice site. It stimulated that cleavage when supplied as a trans-acting RNA containing only 42 nucleotides of intron sequence. The relevance of our findings to in vivo trans-splicing mechanisms is discussed.


2009 ◽  
Vol 14 (8) ◽  
pp. 1089-1100 ◽  
Author(s):  
Meg Boothby ◽  
Kirsty C McGee ◽  
Jeremy W Tomlinson ◽  
Laura L Gathercole ◽  
Philip G McTernan ◽  
...  

2005 ◽  
Vol 280 (49) ◽  
pp. 40398-40401 ◽  
Author(s):  
Junghee Lee ◽  
Chun-Hyung Kim ◽  
David K. Simon ◽  
Lyaylya R. Aminova ◽  
Alexander Y. Andreyev ◽  
...  

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