Coupling of proteolysis to ATP hydrolysis upon Escherichia coli Lon-protease functioning: II. Hydrolysis of ATP and activity of the enzyme peptide hydrolase sites

The absence of direct correlation between the efficiency of functioning of ATPase and peptide hydrolase sites of Lon protease was revealed. It was sho wn that Lon protease is an allosteric enzyme, in which the catalytic activi ty of peptide hydrolase sites is provided by the binding of nucleotides, th eir magnesium complexes, and free magnesium ions in the enzyme ATPase sites . It was revealed that the ADP-Mg complex, an inhibitor of the native enzym e, is an activator of the Lon-K362Q (the Lon protease mutant in the ATPase site). Variants of functional contacts between different sites of the enzym e are considered. It was established that two ways of signal transduction f rom the ATPase sites to peptide hydrolase ones exist in the Lon protease ol igomer-intra- and intersubunit ways. The enzyme ATPase sites are suggested to be located in the areas of the complementary surfaces of subunits. It is hypothesized that upon degradation of protein substrates by the E. coli Lo n protease in vivo ATP hydrolysis acts as a factor of limitation of the enz yme degrading activity.