ISSN:
1432-0614
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Abstract The glucoamylase gene of the yeast Arxula adeninivorans Ls3 has been cloned from a genomic library and sequenced. The gene could be localized on chromosome 2 from A. adeninivorans and comprises 1875 bp. The first 16 N-terminal amino acids represent the signal sequence for entering the endomembrane system. Comparing the amino acid sequence from this glucoamylase with those of other fungal glucoamylases shows that the glucoamylase of strain Ls3 has a homology to the glucoamylases from Rhizopus oryzae (32.6%), Saccharomycopsis fibuligera (23.1%), Aspergillus niger (22.1%), and Saccharomyces diastaticus (15.4%). No homology could be detected to the glucoamylase of Schwanniomyces occidentalis. By using the GAL1 promoter from Saccharomyces cerevisiae within an autonomously replicating plasmid it was possible to express the isolated Arxula glucoamylase gene in Saccharomyces cerevisiae. The transformants secreted 95% of the enzyme into the culture medium. The N termini of glucoamylases synthesized in A. adeninivorans and S. cerevisiae transformants are identical, which means that the signal sequences were cleaved at the same positions during maturation of the proteins. The highest glucoamylase activities were reached in the culture medium of S. cerevisiae transformants after 36 h of fermentation. Northern hybridization showed that the glucoamylase transcripts were formed continuously for up to 70 h. These results reveal that the glucoamylase is expressed and secreted more rapidly in the S. cerevisiae transformants than in A. adeninivorans Ls3.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002530050607
Permalink
