An elastic rod model of a protein-bound DNA loop is adapted for application in multi-scale simulations of
protein-DNA complexes. The classical Kirchhoff system of equations which describes the equilibrium structure
of the elastic loop is modified to account for the intrinsic twist and curvature, anisotropic bending properties,
and electrostatic charge of DNA. The effects of bending anisotropy and electrostatics are studied for the DNA
loop clamped by the lac repressor protein. For two possible lengths of the loop, several topologically different
conformations are predicted and extensively analyzed over the broad range of model parameters describing
DNA bending and electrostatic properties. The scope and applications of the model in already accomplished
and in future multi-scale studies of protein-DNA complexes are discussed.