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Critical amino acids... good idea, but which ones? Lacking any inspiration, you decide to introduce changes at random and hope for the best. To accomplish this, you use error-prone PCR to create many random mutations in the gene. Amongst these mutant genes (you hope!) are those that encode versions of UDP-glucose dehydrogenase that interact less well with each other and will not precipitate even at high concentration.
Unfortunately, the vast majority of mutants will precipitate just as badly as before, and screening thousands of E. coli colonies for the few that don't precipitate is much too painful. You need a trick that somehow makes a colony with unprecipitated UDP glucose dehydrogenase jump up and down. |