Topoisomerase I in actively growing plasmodia and during differentiation of the slime mold Physarum polycephalum.
A type I topoisomerase has been purified from nuclei of a slime mold Physarum polycephalum and its activity was tested during spherulation. The final preparation contained a single polypeptide of about 100 kDa. Basic properties of Physarum topoisomerase I (substrate specificity, ionic requirement, sensitivity to inhibitors) were similar to those of topoisomerases from higher eukaryotes. Specific features of Physarum enzyme were that it was rapidly inactivated at 45 degrees C and did not react with antibodies against human topoisomerase I. The activity of topoisomerase I in developed dormant spherules decreased approx. 2-fold, as compared with a 4-fold decrease of RNA and a 10-fold decrease of DNA synthesis. Basic properties of the enzyme remained unchanged during spherulation.
Staron
K
K
Department of Biochemistry, Warsaw University, Poland.
Kowalska-Loth
B
B
Czerwinski
R M
RM
Bandorowska
J
J
Guberska
J
J
D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004271:DNA, Fungal / Q000235:genetics; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D007074:Immunoglobulin G / Q000378:metabolism; D010804:Physarum / Q000201:enzymology* / Q000254:growth & development; D013379:Substrate Specificity; D013696:Temperature
D004271:DNA, Fungal; D007074:Immunoglobulin G; D004264:DNA Topoisomerases, Type I