small-angle X-ray scattering analysis shows that the enzyme adopts a rigid conformation in solution, where the N-terminal acetyltransferase domain is fixed to the C-terminal phosphotransferase domain and not loosely tethered. The addition of acetyl-coenzyme A, coenzyme A, GDP, guanosine 5'-[beta,gamma-imido]triphosphate, and combinations thereof to the protein result in only modest changes to the radius of gyration of the enzyme, which are not consistent with any large changes in enzyme structure upon binding. These results imply some selective advantage to the bifunctional enzyme beyond coexpression as a single polypeptide, likely linked to an improvement in enzymatic properties. The rigid structure may contribute to improved electrostatic steering of aminoglycoside substrates toward the two active sites, which may provide such an advantage |
Staphylococcus aureus |