scholarly journals The yeast mitochondrial succinylome: Implications for regulation of mitochondrial nucleoids

2021 ◽  
pp. 101155
Author(s):  
Jan Frankovsky ◽  
Barbora Keresztesová ◽  
Jana Bellová ◽  
Nina Kunová ◽  
Nikola Čanigová ◽  
...  
Keyword(s):  
Mitochondrial Nucleoids

scholarly journals The AAA+ protein ATAD3 has displacement loop binding properties and is involved in mitochondrial nucleoid organization

2007 ◽  
Vol 176 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Jiuya He ◽  
Chih-Chieh Mao ◽  
Aurelio Reyes ◽  
Hiroshi Sembongi ◽  
Miriam Di Re ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Uncharacterized Protein ◽  
Supercoiled Dna ◽  
Recombinant Fragment ◽  
Loop Region ◽  
Mitochondrial Nucleoids ◽  
Marked Preference ◽  
D Loop ◽  
Aaa Protein

Many copies of mammalian mitochondrial DNA contain a short triple-stranded region, or displacement loop (D-loop), in the major noncoding region. In the 35 years since their discovery, no function has been assigned to mitochondrial D-loops. We purified mitochondrial nucleoprotein complexes from rat liver and identified a previously uncharacterized protein, ATAD3p. Localization studies suggested that human ATAD3 is a component of many, but not all, mitochondrial nucleoids. Gene silencing of ATAD3 by RNA interference altered the structure of mitochondrial nucleoids and led to the dissociation of mitochondrial DNA fragments held together by protein, specifically, ones containing the D-loop region. In vitro, a recombinant fragment of ATAD3p bound to supercoiled DNA molecules that contained a synthetic D-loop, with a marked preference over partially relaxed molecules with a D-loop or supercoiled DNA circles. These results suggest that mitochondrial D-loops serve to recruit ATAD3p for the purpose of forming or segregating mitochondrial nucleoids.

The Mitochondrial Nucleoid Protein, Mgm101p, of Saccharomyces cerevisiae Is Involved in the Maintenance of ρ+ and ori/rep-Devoid Petite Genomes but Is Not Required for Hypersuppressive ρ− mtDNA

Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1389-1400
Author(s):  
Xiao Ming Zuo ◽  
G Desmond Clark-Walker ◽  
Xin Jie Chen
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mitochondrial Rna ◽  
Mtdna Copy Number ◽  
Mitochondrial Rna Polymerase ◽  
Mitochondrial Nucleoids ◽  
Mtdna Replication ◽  
Sensitive Allele ◽  
Discriminatory Effect

Abstract The Saccharomyces cerevisiae MGM101 gene encodes a DNA-binding protein targeted to mitochondrial nucleoids. MGM101 is essential for maintenance of a functional ρ+ genome because meiotic segregants, with a disrupted mgm101 allele, cannot undergo more than 10 divisions on glycerol medium. Quantitative analysis of mtDNA copy number in a ρ+ strain carrying a temperature-sensitive allele, mgm101-1, revealed that the amount of mtDNA is halved each cell division upon a shift to the restrictive temperature. These data suggest that mtDNA replication is rapidly blocked in cells lacking MGM101. However, a small proportion of meiotic segregants, disrupted in MGM101, have ρ− genomes that are stably maintained. Interestingly, all surviving ρ− mtDNAs contain an ori/rep sequence. Disruption of MGM101 in hypersuppressive (HS) strains does not have a significant effect on the propagation of HS ρ− mtDNA. However, in petites lacking an ori/rep, disruption of MGM101 leads to either a complete loss or a dramatically decreased stability of mtDNA. This discriminatory effect of MGM101 suggests that replication of ρ+ and ori/rep-devoid ρ− mtDNAs is carried out by the same process. By contrast, the persistence of ori/rep-containing mtDNA in HS petites lacking MGM101 identifies a distinct replication pathway. The alternative mtDNA replication mechanism provided by ori/rep is independent of mitochondrial RNA polymerase encoded by RPO41 as a HS ρ− genome is stably maintained in a mgm101, rpo41 double mutant.

scholarly journals Mitochondrial nucleoids maintain genetic autonomy but allow for functional complementation

2008 ◽  
Vol 181 (7) ◽  
pp. 1117-1128 ◽  
Author(s):  
Robert W. Gilkerson ◽  
Eric A. Schon ◽  
Evelyn Hernandez ◽  
Mercy M. Davidson
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Molecular Mechanism ◽  
Cell Lines ◽  
Mitochondrial Protein ◽  
Functional Complementation ◽  
Mitochondrial Protein Synthesis ◽  
Protein Assemblies ◽  
Mtdna Mutations ◽  
Mitochondrial Nucleoids

Mitochondrial DNA (mtDNA) is packaged into DNA-protein assemblies called nucleoids, but the mode of mtDNA propagation via the nucleoid remains controversial. Two mechanisms have been proposed: nucleoids may consistently maintain their mtDNA content faithfully, or nucleoids may exchange mtDNAs dynamically. To test these models directly, two cell lines were fused, each homoplasmic for a partially deleted mtDNA in which the deletions were nonoverlapping and each deficient in mitochondrial protein synthesis, thus allowing the first unequivocal visualization of two mtDNAs at the nucleoid level. The two mtDNAs transcomplemented to restore mitochondrial protein synthesis but were consistently maintained in discrete nucleoids that did not intermix stably. These results indicate that mitochondrial nucleoids tightly regulate their genetic content rather than freely exchanging mtDNAs. This genetic autonomy provides a molecular mechanism to explain patterns of mitochondrial genetic inheritance, in addition to facilitating therapeutic methods to eliminate deleterious mtDNA mutations.

scholarly journals Characterization of the structure and DNA complexity of mung bean mitochondrial nucleoids

2011 ◽  
Vol 31 (3) ◽  
pp. 217-224 ◽  
Author(s):  
Yih-Shan Lo ◽  
Lin-June Hsiao ◽  
Ning Cheng ◽  
Alexandra Litvinchuk ◽  
Hwa Dai
Keyword(s):  
Mung Bean ◽  
Mitochondrial Nucleoids

scholarly journals Mitochondrial HMG-Box Containing Proteins: From Biochemical Properties to the Roles in Human Diseases

Biomolecules ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1193 ◽  
Author(s):  
Veronika Vozáriková ◽  
Nina Kunová ◽  
Jacob A. Bauer ◽  
Ján Frankovský ◽  
Veronika Kotrasová ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Regulation Of Gene Expression ◽  
Protein Structures ◽  
High Mobility ◽  
Biochemical Properties ◽  
Structural Basis ◽  
Comprehensive Overview ◽  
Hmg Box ◽  
Mitochondrial Transcription Factor ◽  
Mitochondrial Nucleoids

Mitochondrial DNA (mtDNA) molecules are packaged into compact nucleo-protein structures called mitochondrial nucleoids (mt-nucleoids). Their compaction is mediated in part by high-mobility group (HMG)-box containing proteins (mtHMG proteins), whose additional roles include the protection of mtDNA against damage, the regulation of gene expression and the segregation of mtDNA into daughter organelles. The molecular mechanisms underlying these functions have been identified through extensive biochemical, genetic, and structural studies, particularly on yeast (Abf2) and mammalian mitochondrial transcription factor A (TFAM) mtHMG proteins. The aim of this paper is to provide a comprehensive overview of the biochemical properties of mtHMG proteins, the structural basis of their interaction with DNA, their roles in various mtDNA transactions, and the evolutionary trajectories leading to their rapid diversification. We also describe how defects in the maintenance of mtDNA in cells with dysfunctional mtHMG proteins lead to different pathologies at the cellular and organismal level.

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