  Using the quark-meson coupling model with the cloudy bag, we construct the
equation of state for neutron stars with hyperons in SU(3) flavor symmetry. The
hyperfine interaction due to the gluon exchange and the pion-cloud effect
inside a baryon is taken into account in vacuum and nuclear matter. We
investigate how the quark degrees of freedom and the exchanges of gluon and
pion between two quarks affect the properties of nuclear and neutron-star
matter. It is found that the variation of baryon substructure in matter plays
an important role in supporting massive neutron stars.
