Evidence for a nucleotide-dependent topoisomerase activity from yeast mitochondria

Yeast mitochondria were found to contain a novel topoisomerase-like activity which required nucleoside di-or tri-phosphates as a cofactor. ADP supported activity as effectively as ATP and the optimal concentration for each was approximately 20 microM. None of the other standard ribo- or deoxyrib-onu...

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Bibliographic Details
Published in:Current genetics 1994-12, Vol.27 (1), p.31-37
Main Authors: Ezekiel, U R, Towler, E M, Wallis, J W, Zassenhaus, H P
Format: Article
Language:English
Subjects:
activador enzimatico
activateur d' enzyme
Adenosine Diphosphate - pharmacology
Adenosine Triphosphate - analogs & derivatives
Adenosine Triphosphate - pharmacology
Adenylyl Imidodiphosphate - pharmacology
adn
dna
DNA Ligases - metabolism
DNA Topoisomerases, Type I - metabolism
DNA, Bacterial - metabolism
DNA, Superhelical - metabolism
enzyme activators
Ethidium - pharmacology
Fungal Proteins - antagonists & inhibitors
Fungal Proteins - metabolism
Hydrogen-Ion Concentration
isomerasas
isomerase
isomerases
levadura
levure
mitochondria
Mitochondria - enzymology
mitochondrie
mitocondria
nucleotide
nucleotides
Nucleotides - physiology
nucleotidos
Plasmids - genetics
Saccharomyces cerevisiae - enzymology
Topoisomerase I Inhibitors
yeasts
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Summary:Yeast mitochondria were found to contain a novel topoisomerase-like activity which required nucleoside di-or tri-phosphates as a cofactor. ADP supported activity as effectively as ATP and the optimal concentration for each was approximately 20 microM. None of the other standard ribo- or deoxyrib-onucleotides could fully substitute for either ADP or ATP. The non-hydrolyzable ATP analogs, adenosine-5'-0-(3-thiotriphosphate) (ATP-gamma-S), adenylyl (beta, gamma-methylene) (AMP-PCP), and andenyl-imidodiphosphate (AMP-PNP) also supported activity suggesting that the nucleotide cofactor regulated topoisomerase activity rather than serving as an energy donor in the reaction. The mitochondrial topoisomerase activity relaxed both positively and negatively supercoiled DNA. It was not inhibited by concentrations of ethidium bromide up to 2 micro g/ml nor by either nalidixic or oxolinic acids; novobiocin, coumermycin, and berenil inhibited the activity. Genetic and biochemical analysis of the mitochondrial topoisomerase activity indicated that it was not encoded by the nuclear TOP1, TOP2, and TOP3 genes.
ISSN:0172-8083
1432-0983
DOI:10.1007/BF00326576