Open AccessSubstrate Specificity and Adenosine Triphosphatase Activity of the ATP‐Dependent Deoxyribonuclease, of Bacillus subtilis
Author(s) -
DOLY Janine,
ROSCOUËT Daniéle,
ANAGNOSTOPOULOS Constantine
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb05172.x
Subject(s) - dna , bacillus subtilis , phosphodiester bond , atpase , biochemistry , exonuclease , enzyme , deoxyribonuclease i , atp hydrolysis , biology , deoxyribonuclease , adenosine triphosphate , chemistry , biophysics , dna polymerase , rna , bacteria , genetics , gene , base sequence
Studies on the specificity of the ATP‐dependent DNase of Bacillus subtilis 168, carried out with pure enzyme at the optimal conditions for its action, have shown that the substrate is double‐stranded linear DNA. Linear single‐stranded DNA (separated strands of B. subtilis DNA and linear phage fd DNA) is not attacked, neither are there any circular forms (supercoiled or nicked simian virus 40 and circular single‐stranded fd DNAs). The double‐stranded DNA can be completely hydrolysed, the limit products being, almost exclusively, mononucleotides. The presence of terminal phosphate residues in the substrate (either at the 3′ or the 5′ end) is not necessary for enzyme action. This DNase appears therefore to be an exonuclease processively liberating mononucleotides from both strands of the native linear DNA. ATP (indispensable for the DNase reaction) is also hydrolysed by the enzyme, to ADP and inorganic orthophosphate (P i ) in the presence of DNA. The apparent K m for ATP, in the ATPase reaction, is 0.15 mM. At high ATP concentrations, which inhibit the DNase activity, there is activation of the ATPase reaction. Three molecules of ATP are consumed for each DNA phosphodiester bond split, at optimal conditions for DNase activity.