GyrAGyrB

gyrAgyrB is a term used to denote a hypothetical fusion protein that combines features of the bacterial DNA gyrase subunits GyrA and GyrB. In this context, gyrAgyrB refers to an engineered single polypeptide intended either to mimic aspects of the native enzyme or to probe how the GyrA and GyrB domains cooperate during catalysis. This concept is distinct from the native gyrase, which in most bacteria consists of two GyrA and two GyrB subunits assembling into a GyrA2GyrB2 heterotetramer that couples DNA strand passage with ATP-driven supercoiling.

If constructed, the protein would conceptually integrate the DNA cleavage and religation domain associated with GyrA and the ATPase domain associated with GyrB, connected by a linker. Variants vary in linker length and domain order. The activity and stability of such a chimera depend on proper folding, interdomain communication, and regulatory constraints; many attempts yield proteins with reduced or altered activity compared with the native enzyme. Researchers use gyrAgyrB models to study domain crosstalk, the requirements for substrate binding, and the minimal features necessary for DNA supercoiling.

Applications and implications include gaining insight into the mechanism of type II topoisomerases, informing antibiotic target studies, and serving as a platform for protein engineering experiments. Ethical and biosafety considerations apply to the creation and handling of engineered topoisomerases.

See also: DNA gyrase, GyrA, GyrB, type II topoisomerase.