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Considerable evidence supports a defect at the level of chromatin structure or recognition of that structure in cells from patients with the human genetic disorder ataxia-telangiectasia. Accordingly, we have investigated the activities of enzymes that alter the topology of DNA in Epstein Barr Virus-transformed lymphoblastoid cells from patients with this syndrome. Reduced activity of DNA topoisomerase II, determined by unknotting of P4 phage DNA, was observed in partially purified extracts from 5 ataxia-telangiectasia cell lines. The levels of enzyme activity was reduced substantially in 4 of these cell lines and to a lesser extent in the other cell line compared to controls. DNA topoisomerase I, assayed by relaxation of supercoiled DNA, was found to be present at comparable levels in both cell types. Reduced activity of topoisomerase II in ataxia-telangiectasia is compatible with the molecular, cellular and clinical changes described in this syndrome.
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
January 1990,
Acta biologica Hungarica,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
July 1989,
Carcinogenesis,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
March 1989,
Cancer research,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
February 2013,
Cancer science,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
June 1988,
Biochemical pharmacology,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
March 1984,
International journal of cancer,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
June 1981,
Nature,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
June 1986,
Cancer research,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
February 1989,
Nucleic acids research,
S P Singh, and
R Mohamed, and
C Salmond, and
M F Lavin
October 1992,
Mutation research,
