  Defining a new r-matrix compatible with the scalar product at the basis of
the Chern-Simons action for a particle coupled to (2+1) Lorentzian gravity with
cosmological constant, I show how deformed symmetries of $\kappa$-de Sitter
and, in the vanishing cosmological limit, of $\kappa$-Poincar\'e kind, arise
naturally as quantum-deformation of three dimensional gravity. I obtain
moreover the non-commutative spacetime associated to these kinds of symmetries.
