  We report on dynamic properties of a simple model microswimmer composed of
three spheres and propelling itself in a viscous fluid by spinning motion of
the spheres under zero net torque constraint. At a fixed temperature and
increasing the spinning frequency, the swimmer demonstrates a transition from
dissipation-dominated to a pumping-dominated motion regime characterized by
negative effective friction coefficient. In the limit of high frequencies, the
diffusion of the swimmer can be described by a model of an active particle with
constant velocity.
