  In this letter we address the issue how synthetic spin-orbit (SO) coupling
can strongly affect three-body physics in ultracold atomic gases. We consider a
system which consists of three fermionic atoms, including two spinless heavy
atoms and one spin-1/2 light atom subjected to an isotropic SO coupling. We
find that SO coupling can induce universal three-body bound states with
negative s-wave scattering length at a smaller mass ratio, where no trimer
bound state can exist if in the absence of SO coupling. The energies of these
trimers are independent of high-energy cutoff, and therefore they are universal
ones. Moreover, the resulting atom-dimer resonance can be effectively
controlled by SO coupling strength. Our results can be applied to systems like
${}^6$Li and ${}^{40}$K mixture.
