  We study a renormalizable SUSY $SO(10)$ GUT model where the Yukawa couplings
of single ${\bf 10}$, single ${\bf \overline{126}}$ and single ${\bf 120}$
fields, $Y_{10},Y_{126},Y_{120}$, account for the quark and lepton Yukawa
couplings and the neutrino mass. We pursue the possibility that
$Y_{10},Y_{126},Y_{120}$ reproduce the correct quark and lepton masses, CKM and
PMNS matrices and neutrino mass differences, and at the same time suppress
dimension-5 proton decays (proton decays via colored Higgsino exchange) through
their texture, so that the soft SUSY breaking scale can be reduced as much as
possible without conflicting the current experimental bound on proton decays.
We perform a numerical search for such a texture, and investigate implications
of that texture on unknown neutrino parameters, the Dirac CP phase of PMNS
matrix, the lightest neutrino mass and the $(1,1)$-component of the neutrino
mass matrix in the charged lepton basis. Here we concentrate on the case when
the active neutrino mass is generated mostly by the Type-2 seesaw mechanism, in
which case the correlation between the suppression of dimension-5 proton decays
and the neutrino parameters is expected to be most direct.
