  We present the results from a multiwavelength campaign of the powerful
Gamma-ray quasar PKS 1510-089. This campaign commenced with a deep Suzaku
observation lasting three days for a total exposure time of 120 ks, and
continued with Swift monitoring over 18 days. Besides Swift observations, the
campaign included ground-based optical and radio data, and yielded a
quasi-simultaneous broad-band spectral energy distribution from 10^9 Hz to
10^{19} Hz. The Suzaku observation provided a high S/N X-ray spectrum, which is
well represented by an extremely hard power-law with photon index Gamma ~ 1.2,
augmented by a soft component apparent below 1 keV, which is well described by
a black-body model with temperature kT ~ 0.2 keV. Monitoring by Suzaku revealed
temporal variability which is different between the low and high energy bands,
again suggesting the presence of a second, variable component in addition to
the primary power-law emission.We model the broadband spectrum of PKS 1510-089
assuming that the high energy spectral component results from Comptonization of
infrared radiation produced by hot dust located in the surrounding molecular
torus. In the adopted internal shock scenario, the derived model parameters
imply that the power of the jet is dominated by protons but with a number of
electrons/positrons exceeding a number of protons by a factor ~10. We also find
that inhomogeneities responsible for the shock formation, prior to the
collision may produce bulk-Compton radiation which can explain the observed
soft X-ray excess and possible excess at ~18 keV. We note, however, that the
bulk-Compton interpretation is not unique, and the observed soft excess could
arise as well via some other processes discussed briefly in the text.
