ISSN:
1573-4978
Keywords:
DNA-protein interaction
;
phosphorylation/dephosphorylation
;
Topoisomerase I
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Calf thymus DNA-Topoisomerase I activity was found to be altered by changing in phosphorylation: it was completely inhibited upon dephosphorylation by alkaline phosphatase, but incubation with N II protein kinase and ATP restored the relaxation activity to a level higher than that observed prior to dephosphorylation. The calf thymus Topoisomerase I-mediated DNA cleavage, induced by camptothecin, also proved to be inhibited by dephosphorylation, which, apparently, stabilizes the initial enzymesubstrate complex. We conclude that: - the native protein is partially phosphorylated, - the phosphorylation involvement is essential for the activity expression and also for DNA-protein interaction, - changes in the degree of phosphorylation might be involved in the regulation of DNA processing; that evokes some properties of chromatinic peptide models, which bind DNA only when phosphorylated and leads to the assumption that they represent the minimum functional substrate for N II protein kinase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00422713
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