Studies on the alcohol oxidase (<i>AOX1</i>) promoter of <i>Pichia pastoris</i>

2000 2000

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Abstract (summary)

Pichia pastoris is an outstanding host for high-level heterologous gene expression, but there is still much interest in improving the productivity of recombinant protein production. Ethanol repression of the AOX1 promoter was investigated by using GS115 (Mut+) and MC100-3 (mut) strains expressing intracellular AOX1::lacZ fusions. The addition of 10 mg L−1 ethanol at the start of methanol induction, delayed β-galactosidase production and methanol utilization for four hours in shake flask experiments. When ethanol and acetate were added together, all of the ethanol was converted to acetate, which also represses the AOX1 promoter.

The growth of P. pastoris in a mixture of either glycerol or glucose and methanol follows a diauxic growth, with C1 utilizing enzymes being repressed. Therefore, none of these carbon sources can be used as a mixture with methanol especially in shake flask culture of AOX-deficient P. pastoris. Among the tested carbon sources alanine, sorbitol, mannitol and trehalose did not repress AOX activity when methanol was used as an inducer in mut strain of P. pastoris. A mut strain growing in media containing trehalose, alanine, sorbitol and mannitol with methanol (0.5%) as an inducing agent expressed as much or higher β-galactosidase as compared to the mut+ growing in methanol containing media.

The regulation of the AOX1 promoter of P. pastoris was investigated by systematic deletions and DNA-protein interactions. Using the sequential deletion analysis, the 1120 by 5 upstream region of AOX1 gene was divided into six subfragments. Each fragment had a significant effect on the promoter activity, however, the deletion analysis did not allow the exact localization of the upstream functions. Nevertheless, deletion of the fragment E (−273/−123) resulted in 84% reduction in native promoter activity. The fragments A (−960/−688) and C (−539/−399) contain sequences for DNA binding proteins. We show evidence that these proteins are different since these two fragments do not compete for the same protein by gel shift assay, and their nature remains to be characterized.

Indexing (details)

Molecular biology;
0410: Microbiology
0307: Molecular biology
0369: Genetics
Identifier / keyword
Biological sciences; AOX1 promoter; Alcohol oxidase; Catabolite repression; Pichia pastoris
Studies on the alcohol oxidase (<i>AOX1</i>) promoter of <i>Pichia pastoris</i>
Inan, Mehmet
Number of pages
Publication year
Degree date
School code
DAI-B 62/03, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
049319603X, 9780493196039
Meagher, Michael M.
The University of Nebraska - Lincoln
University location
United States -- Nebraska
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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