gyrd

GyrD is a protein essential for bacterial DNA replication. It is a type II topoisomerase, an enzyme that modifies the topological structure of DNA. Specifically, GyrD is the subunit of DNA gyrase responsible for binding to and cleaving DNA strands. DNA gyrase is a heterotetramer composed of two GyrA subunits and two GyrB subunits. The GyrB subunit is a ATPase that provides the energy for the supercoiling reaction, while the GyrA subunit is responsible for the breakage and rejoining of DNA strands. GyrD is a separate protein that functions in a similar manner to GyrA and is found in some bacterial species, such as *Escherichia coli*. It is involved in the decatenation of newly replicated chromosomes and is essential for cell viability. Mutations in the gyrD gene can lead to resistance to quinolone antibiotics, which target DNA gyrase.