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Z A Janowicz

Publications and source records attributed to Z A Janowicz.

6 recordsLinked to original sources
PubMed1992

Heterologous protein production in yeast.

The exploitation of recombinant DNA technology to engineer expression systems for heterologous proteins represented a major task within the field of biotechnology during the last decade. Yeasts attracted the attention of molecular biologists because of properties most favourable for their use as hosts in heterologous protein production. Yeasts follow the general eukaryotic posttranslational modification pattern of expressed polypeptides, exhibit the ability to secrete heterologous proteins and benefit from an established fermentation technology. Aside from the baker's yeast Saccharomyces cerevisiae, an increasing number of alternative non-Saccharomyces yeast species are used as expression systems in basic research and for an industrial application. In the following review a selection from the different yeast systems is described and compared.

Gene Expression↗
PubMed1991

Simultaneous expression of the S and L surface antigens of hepatitis B, and formation of mixed particles in the methylotrophic yeast, Hansenula polymorpha.

An expression system has been developed for the methylotrophic yeast Hansenula polymorpha and used to co-express both the L (preS1-S2-S) and S hepatitis B surface antigens (HBsAg) under the control of strong methanol-inducible promoters derived from the methanol oxidase and from the formate dehydrogenase genes. A unique feature of this H. polymorpha expression system is the possibility of integrating up to 100 copies of an expression cassette via a multimeric integration mechanism. Several multimeric integrants containing various numbers of L and S expression cassettes were constructed to give a spectrum of strains characterized by different L to S ratios. The expression level of S antigen was 5-8% of the total soluble cell protein. Analysis by sucrose and CsCl density gradient centrifugation and by particle-specific immunoassays demonstrated that the synthesized HBsAg spontaneously assembled into composite subviral particles containing both S and L proteins. Only a minor portion of the L protein was found to be glycosylated. These H polymorpha-derived composite particles can be used for the production of a hepatitis B virus vaccine with the potential for improved immunogenicity due to the presence of a wider spectrum of epitopes and negligible glycosylation.

Base Sequence↗
PubMed1991

Heterologous gene expression in Hansenula polymorpha: efficient secretion of glucoamylase.

We have introduced the glucoamylase gene (GAM1) from Schwanniomyces occidentalis into the genome of the methylotrophic yeast Hansenula polymorpha to study the potential of this organism as a host for high-level expression of a heterologous gene encoding a secretory protein. Transformants of H. polymorpha containing GAM1 under control of the formate dehydrogenase (FMD) promoter are stable and efficiently secrete an active glucoamylase that is faithfully processed and modified. Yields of up to 1.4g/l of active enzyme were obtained at cell densities of 100-130 grams dry weight per liter.

Amino Acid Sequence↗
PubMed1989

Biosynthesis of the peroxisomal dihydroxyacetone synthase from Hansenula polymorpha in Saccharomyces cerevisiae induces growth but not proliferation of peroxisomes.

The DAS gene of Hansenula polymorpha was expressed in Saccharomyces cerevisiae under the control of different promoters. The heterologously synthesized dihydroxyacetone synthase (DHAS), a peroxisomal enzyme in H. polymorpha, shows enzymatic activity in baker's yeast. The enzyme was imported into the peroxisomes of S. cerevisiae not only under the appropriate physiological conditions for peroxisome proliferation (oleic acid media), but also in glucose-grown cells where it induced the enlargement of the few peroxisomes present. This growth process was not accompanied by an increase in the number of microbodies, which suggests a separate control mechanism for peroxisomal proliferation.

Alcohol Oxidoreductases↗
PubMed1985

Cloning and characterization of the DAS gene encoding the major methanol assimilatory enzyme from the methylotrophic yeast Hansenula polymorpha.

A gene library from the methanol utilizing yeast Hansenula polymorpha, constructed in a lambda Charon4A vector, was used to clone the gene encoding a key methanol assimilating enzyme, dihydroxyacetone synthase (DHAS) by differential plaque hybridization. The nucleotide sequence of the 2106 bp structural gene and the 5' and 3' non-coding regions was determined. The deduced amino acid sequence of the protein is in agreement with the apparent molecular weight and amino acid composition of the purified protein. The codon bias is not so pronounced as in some Saccharomyces cerevisiae genes.

Aldehyde-Ketone Transferases↗