The Xenopus laevis mitochondrial protein mtDBP-C cooperatively folds the DNA in vitro.

Mignotte, Bernard; Delain, Etienne; Rickwood, D.; Barat-Gueride, Monique

doi:10.1002/j.1460-2075.1988.tb03273.x

Cited by 14 publications

(14 citation statements)

References 26 publications

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“…The known binding properties of mtDBP-C [ l l ] and electron microscopic studies [12] show that this protein modifies the conformation of the DNA molecule and induces its compaction. Its inhibitory effect on transcription could result from local modification of supercoiling at the level of the promoter region [12] or as a consequence of a modification of the general conformation of the DNA molecule.…”

Section: Discussionmentioning

confidence: 99%

“…Its inhibitory effect on transcription could result from local modification of supercoiling at the level of the promoter region [12] or as a consequence of a modification of the general conformation of the DNA molecule. Through its cooperative binding to the single strands of the bubbles of denaturation present in supercoiled DNA molecules, mtSSB might be able to modify the conformation of the DNA locally.…”

Section: Discussionmentioning

confidence: 99%

“…(a) mtDBP-C: this protein, DNA-binding protein C, binds preferentially to supercoiled DNA irrespective of the sequence [ll]. Electron microscopic analysis of the protein-DNA complexes shows that it induces the formation of superhelical turns locally, leading to the formation of a highly folded structure [12]. (b) mtSSB : this protein, single-stranded DNA-binding protein, binds specifically to single-stranded DNA with a higher affinity for DNA rich in pyrimidines [13].…”

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confidence: 99%

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Effect of DNA conformation on the transcription of mitochondrial DNA

Barat-Gueride

Dufresne

Rickwood

1989

European Journal of Biochemistry

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The importance of the conformation of the DNA template for in vitro transcription experiments was investigated using a mitochondrial RNA polymerase preparation from Xenopus luevis oocyte mitochondria. A premature termination transcription assay has been devised and the levels of the formation of transcriptional complexes have been identified using agarose gel electrophoresis. It was found that accurate initiation of transcription from in vivo promoter sequences was enhanced by supercoiling and that the two mitochondrial DNA-binding proteins, previously characterized by us, inhibited the transcription of DNA as gauged by these assays.Recent studies of mitochondrial transcription have provided information on the precise location of the initiation of transcription and the sequences of promoters for some species [I -31 as well as identifying accessory proteins In Xmopus laeiiis mtDNA overlapping and bidirectional promoters have been located precisely in the non-coding region, their sequences have been determined [3,6] and a factor required for specific transcription has been identified [6]. During oogenesis the frequency of molecules with a displacement loop (D-loop) has been correlated to mitochondriogenesis [9]. However, nothing is known yet about the regulation of replication and transcription of mtDNA. As in the case of other higher eukaryotes, purified X . laevis mtDNA is supercoiled but in vivo it is associated with protein(s) and packaged into a condensed relaxed beaded structure [lo].We have previously reported the characterization of two DNA-binding proteins isolated from purified oocyte mitochondria. (a) mtDBP-C: this protein, DNA-binding protein C, binds preferentially to supercoiled DNA irrespective of the sequence [ll]. Electron microscopic analysis of the protein-DNA complexes shows that it induces the formation of superhelical turns locally, leading to the formation of a highly folded structure [12]. (b) mtSSB : this protein, single-stranded DNA-binding protein, binds specifically to single-stranded DNA with a higher affinity for DNA rich in pyrimidines [13]. Both in vivo and by in vitro reconstitution experiments this protein has been found associated to the single-stranded DNA of the D-loop [14].Correspondence to M. Barat-Gueride, Laboratoire de Biologie Gi-ni-rale, Univcrsiti-de Paris-Sud, Bltiment 400, F-91405 Orsay Cedex, FranceAhhreviutions. DBP-C, DNA-binding protein C; SSB, singleslranded-DNA binding protein; mt, mitochondrial.As the modulation of supercoiling can occur not only through enzymatic activities (topoisomerases) but also through the binding of proteins, this work was carried out to investigate the importance of the conformation of the DNA template and the effect of the DNA-binding proteins on the in vitro transcription mediated by homologous mitochondrial RNA polymerase. MATERIALS AND METHODS Purification of mitochondria1 R N A polymeraseMitochondria were preparcd from frcshly disscctcd ovaries of two female Xenopus hevis which had been injected with 1000 U human chorionic gonado...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Effect of DNA conformation on the transcription of mitochondrial DNA

Barat-Gueride

Dufresne

Rickwood

1989

European Journal of Biochemistry

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“…The mtDNA-specific gamma-DNA polymerase (EC 2.7.7.7) has been partially purified in a number of vertebrates (Bertazzoni et al 1977;Wernette and Kaguni 1986). Topoisomerases I and II (Castora and Lazarus 1984;Fairfield et at 1985;Lazarus et al 1987) and additional proteins, presumably implicated in both elongation of the nascent strands and maturation of novel molecules, have been partially purified in several organisms (Tomkinson and Linn 1986;Cordonnier et al 1987;Mignotte et al 1988). None of these factors, however, has been characterized in humans, and no information is available on the corresponding human genes.…”

Section: Candidate Genesmentioning

confidence: 99%

Nucleus‐driven mutations of human mitochondrial DNA

Zeviani

1992

J of Inher Metab Disea

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Neuromuscular disorders due to abnormalities of mitochondrial energy supply have become an important area of human pathology. In particular, lesions of the mitochondrial genome (mtDNA), a small extra-nuclear chromosome which encodes 13 subunits of the respiratory chain complexes, are responsible for a steadily increasing number of neuromuscular syndromes. In addition to sporadic or maternally-inherited mutations, either qualitative or quantitative abnormalities of mtDNA can be transmitted as Mendelian traits, leading to well-defined mitochondrial encephalomyopathies. The latter are presumably caused by mutations in still unknown nucleus-encoded genes which deleteriously interact with the mitochondrial genome. These observations are of importance from both clinical and theoretical points of view, because they are the first examples of diseases produced by abnormalities of the nuclear control over mitochondrial biogenesis.

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“…Mitochondria1 HM and bacterial HU appear to be functionally similar, since HM can complement the phenotype of E. coli cells lacking HU, although there is no structural similarity between these two proteins (Megraw and Chae, 1993). Proteins similar to yeast HM have been reported from human (Parisi and Clayton, 1991) and Xenopus laevis (Mignotte et al, 1988) mitochondria. Proteins similar to yeast HM have been reported from human (Parisi and Clayton, 1991) and Xenopus laevis (Mignotte et al, 1988) mitochondria.…”

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confidence: 72%

The Recombinant Product of theChryptomonasφ Plastid GenehlpAis an Architectural Hu‐Like Protein that Promotes the Assembly of Complex Nucleoprotein Structures

Crasser

Ritt

Krieg

et al. 1997

European Journal of Biochemistry

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The HlpA protein which is encoded by the hlpA gene in the plastid genome of the cryptomonad alga Chryptomonas phi is structurally related to the non-sequence-specific DNA-binding and DNA-bending HU family of chromatin-associated proteins. The expression of the HlpA protein complements the mutant phenotype of Bacillus subtilis cells impaired in the Hbsu protein (B. subtilis HU), as measured by the resistance of the cells to methylmethane sulphonate. To analyse the interactions of HlpA with DNA, we expressed the protein in Escherichia coli and purified it to homogeneity. HlpA interacts preferentially with four-way junction DNA or DNA minicircles, when compared with linear DNA, recognising DNA structure. HlpA and E. coli HU display comparable affinities for all types of DNA tested; however, HlpA exhibits a stronger tendency to self-associate in the presence of DNA. Accordingly, HlpA oligomerises more readily than HU in protein crosslinking experiments. In the presence of topoisomerase I, HlpA constrains negative superhelical turns in closed circular plasmid DNA. The HlpA protein mediates the joining of distant recombination sites into a complex nucleoprotein structure, as judged by beta-mediated site-specific recombination. The results presented provide evidence that HlpA is a functional plastid equivalent of nuclear and mitochondrial HMG1-like proteins and bacterial HU proteins.

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The Xenopus laevis mitochondrial protein mtDBP-C cooperatively folds the DNA in vitro.

Cited by 14 publications

References 26 publications

Effect of DNA conformation on the transcription of mitochondrial DNA

Effect of DNA conformation on the transcription of mitochondrial DNA

Nucleus‐driven mutations of human mitochondrial DNA

The Recombinant Product of theChryptomonasφ Plastid GenehlpAis an Architectural Hu‐Like Protein that Promotes the Assembly of Complex Nucleoprotein Structures

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