A Mycobacterium smegmatis gyrase B specific monoclonal antibody reveals association of gyrase A and B subunits in the cell

DNA gyrase is a unique topoisomerase, which plays important roles in macrom olecular events like DNA replication, transcription and genetic recombinati on. In this study a high affinity monoclonal antibody to the gyrase B (GyrB ) subunit of Mycobacterium smegmatis was characterized, which did not cross -react with either the Escherichia coli GyrB subunit or with GyrB subunits from other mycobacterial species. The antibody recognized an epitope in the N-terminus, novobiocin-binding domain of GyrB. Immunoprecipitation of gyra se from M. smegmatis cell lysate revealed an association, mediated by ionic interactions, of gyrase A and GyrB subunits in the cell. This antibody is a valuable tool for structure-function analysis and immunocytological studi es of myobacterial DNA gyrase. (C) 2001 Federation of European Microbiologi cal Societies. Published by Elsevier Science B.V. All rights reserved.