Pichia expression system?

Dom Spinella dspinella at chugaibio.com
Thu Aug 7 10:01:58 EST 1997

James R. Bone writes:
> Is anyone using the Pichia system for expression and purification
> heterologous proteins.
> Please reply if you have any experience with Pichia.
> Do you get more protein than Saccharomyces?
> Is the secreted (alpha-factor pre-pro signal peptide) system useful.
> Is it as easy to work with as Saccharomyces?
> What are the best vectors?
> Any disadvantages?
> Thanks
> JB

Yes, our lab has tried Pichea expression.  Yes, you get a ton of protein
-- more than with practically any other system -- even Bac virus.  It is
quite easy to work with. The signal peptide system is useful for some
proteins.  We have observed however one huge disadvantage (at least in
our hands).  In a word -- proteolysis.  I have seen no other expression
system in which the expressed proteins are so degraded and so quickly. 
We have actually abandoned the system for this reason despite the ease
of use and the high expression levels.  I suppose if you are working
with a very stable protein which is extremely resistant to proteases,
Pichea can be a good choice.  Otherwise, I'd stay away from it until
they come up with protease deficient strains (which I believe is in the
works).  Good luck.  -- D.G. Spinella

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