Biochemical complementation studies in vitro of gyrase subunits from different species.
To investigate the functional equivalence of DNA gyrase subunits from different bacterial sources hybrid enzymes were formed using purified A and B subunits from three species of Streptomycetes, E. coli and B. subtilis. The activity of gyrase hybrids composed of heterologous gyr A and gyr B proteins and of the gyrases containing homologous subunits was characterized by binding studies and a cleavage assay with two different DNA fragments. Likewise the enzyme activity was monitored by the super-coiling and relaxation assay with pBR322 DNA. We found that cleavage reactions are largely determined by the source of the gyr B subunits whereas DNA supercoiling and relaxation reactions of pBR322 catalyzed by DNA gyrase are limited to a combination of homologous A and B subunits or of heterologous A and B subunits from the taxonomically related bacteria Streptomycetes.
Simon
H
H
Institut für Molekularbiologie, Friedrich-Schiller-Universität Jena, Germany.
Roth
M
M
Zimmer
C
C
D001412:Bacillus subtilis / Q000201:enzymology*; D004250:DNA Topoisomerases, Type II / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D046911:Macromolecular Substances; D010957:Plasmids; D055503:Protein Multimerization; D013302:Streptomyces / Q000201:enzymology*; D013305:Streptomyces griseus / Q000201:enzymology; D013379:Substrate Specificity
D046911:Macromolecular Substances; D004250:DNA Topoisomerases, Type II