EXPRESSION OF HUMAN THYROID PEROXIDASE IN THE YEASTS SACCHAROMYCES-CEREVISIAE AND HANSENULA-POLYMORPHA

Saccharomyces cerevisiae and the methylotrophic yeast Hansenula polymo rpha have been used to express both full-length and a large hydrophili c domain of human thyroid peroxidase (TPO). Expression of TPO in S. ce revisiae, using the natural signal sequence or the yeast alpha-mating factor (MFalpha) signal sequence, resulted in undetectable or very low levels of recombinant TPO production. However, TPO was expressed when the natural TPO leader sequence was replaced by the yeast STE2 signal sequence. This recombinant TPO reacted with both rabbit anti-human TP O polyclonal and mouse antihuman TPO monoclonal antibodies on Western blots. In the case of H. polymorpha, TPO expression was achieved when the natural TPO leader sequence was replaced by the MFalpha leader and the construct placed under the control of the methanol-regulated prom oter from the methanol oxidase gene. The recombinant TPO produced in H . polymorpha reacted with both TPO polyclonal and TPO monoclonal antib odies. No TPO was produced when the signal sequence of SUC2 (invertase ) or the TPO natural signal sequence was used to direct expression.