| Abstract: |
DNA sequence analysis of Escherichia coli parC and parE, encoding the subunits of topoisomerase IV (Topo IV) (Kato, J.-I., Suzuki, H., and Ikeda, H. (1992) J. Biol. Chem. 267, 25676-25684), showed that ParC was 22 amino acids longer on the N terminus and ParE was 29 amino acids longer on the C terminus than reported previously. E. coli strains bearing bacteriophage T7 RNA polymerase-based expression plasmids carrying both intact and truncated parC and parE were used to overproduce the ParC and ParE proteins. Full- length ParC and ParE were required to reconstitute Topo IV activity, whereas the truncated ParC and ParE were inactive. Topo IV activity was supported only by ATP or dATP. The [ATP]( 1/2 ) for DNA relaxation was 0.45 mM, almost 25- fold higher than the [ATP]( 1/2 ) for decatenation of kinetoplast DNA. Topo IV activity was inhibited by the quinolone and coumarin antibiotics, although the concentrations required for 50% inhibition of activity were 3-30-fold higher than those required to inhibit DNA gyrase. The norfloxacin-induced DNA cleavage patterns of Topo IV and DNA gyrase were distinct but overlapping. The native forms of ParC and ParE were a dimer and a monomer, respectively; whereas the active form of Topo IV was a heterotetramer, ParC2ParE2. The inactivity of the truncated forms of ParC and ParE could be attributed to their failure to form the heterotetramer. |
| Keywords: |
nonhuman; enzyme inhibition; enzyme activity; structure activity relation; amino acid sequence; molecular sequence data; amino terminal sequence; escherichia coli; polymerization; base sequence; dna sequence; protein subunit; sequence homology, nucleic acid; enzyme structure; dna, bacterial; enzyme purification; dna topoisomerase iv; electrophoresis, polyacrylamide gel; dna topoisomerase; dna topoisomerases, type i; priority journal; article; lateolabrax japonicus; electrophoresis, agar gel; support, u.s. gov't, p.h.s.; chromatography, deae-cellulose; ikeda
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