Molecular analysis of the DNA gyrB gene from Myxococcus xanthus

1 Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel 2 Department of Genetics, University of Leicester, Leicester LE1 7RH, UK ABSTRACT Summary: DNA gyrase, an essential type II topoisomerase, mediates negative supercoiling of the bacterial chromosome, thereby affecting the processes of DNA replication, transcription, recombination and repair. The gyrB gene from the Gram-negative soil bacterium Myxococcus xanthus was sequenced. The sequence predicts a protein of 815 amino acid residues displaying significant homology to all known GyrB proteins. A 6-His-GyrB fusion protein was overexpressed in Escherichia coli and purified to near homogeneity using affinity chromatography on Ni-nitrilotriacetic acid-agarose and novobiocin-Sepharose columns. The fusion protein bound novobiocin and cross-reacted with anti- E. coli GyrB antibodies, indicating structural and functional similarities to the E. coli DNA GyrB. The gene was mapped to the region of the origin of replication ( oriC of M. xanthus. * Author for correspondence: Elisha Orr. Tel: +972 3 6407624. Fax: 4-972 3 6414138/6429377. e-mail: orr@le.ac.uk Keywords: Myxococcus xanthus , DNA gyrase B, topoisomerase Present address: Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel.