Construction and characterization of Pichia pastoris strains for labeling aromatic amino acids in recombinant proteins

Mei M. Whittaker, James W. Whittaker

    Research output: Contribution to journalArticlepeer-review

    17 Scopus citations


    Strains of the methylotrophic yeast Pichia pastoris auxotrophic for the aromatic amino acids (tyrosine, phenylalanine, and tryptophan) have been constructed by targeted gene disruption for protein labeling applications. Three strains, with defects in ARO1 (coding for a homolog of the arom pentafunctional enzyme), ARO7 (coding for chorismate mutase), and TYR1 (coding for prephenate dehydrogenase), have been engineered in a P. pastoris ura3Δ1 parent strain using standard methods. The nutritional requirements of these auxotrophic strains have been characterized and their utility as expression hosts for labeling recombinant proteins has been demonstrated. All three strains show a surprising sensitivity to rich culture medium and must be grown in supplemented minimal medium. The tyr1::URA3 strain in particular is strongly inhibited by tryptophan, and to a lesser extent by phenylalanine, leucine, and isoleucine. Highly efficient incorporation of exogenously supplied amino acids by these three auxotroph strains has been demonstrated using recombinant galactose oxidase. Stereochemically pure l-amino acids and racemic d,l-mixtures serve nearly equally well to support protein expression and labeling. These strains allow efficient labeling of aromatic amino acids in recombinant proteins, supporting NMR structural biology and a wide range of other biophysical studies.

    Original languageEnglish (US)
    Pages (from-to)266-274
    Number of pages9
    JournalProtein Expression and Purification
    Issue number2
    StatePublished - Jun 2005


    • Aromatic amino acids
    • Auxotroph
    • Galactose oxidase
    • Pichia pastoris
    • Strain construction

    ASJC Scopus subject areas

    • Biotechnology


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