Analysis of protein traffic in defined secretion pathway mutants of Aspergillus niger.

Peter J. Punt, Anneke Drint-Kuijvenhoven, Vivi Joosten, Ingeborg A. van Gemeren, and Cees A.M.J.J. van den Hondel.


A major part of our research is focused on the understanding of the molecular mechanisms underlying efficient protein-secretion by filamentous fungi. Two lines of research are followed to identify key points in the secretion pathway. In a first empirical research line the role of major ER-chaperone protein BiP on protein secretion was studied. A second research line was based on a systematic analysis of the fungal secretion pathway. Based on results obtained in S. cerevisiae, it was clear that the various transport steps of the secretion pathway are depending different stage-specific small GTPases. The A. niger genes encoding the most relevant of these GTPases were cloned. From one of these genes, sarA, of which the gene product is expected to play a role in one of the early transport steps from ER to Golgi, specific mutant alleles were generated. Introduction of the alleles into A. niger resulted specific conditional A.niger sarA mutants. Analysis of secretion characteristics of both BiP-overproducing and sarA mutant strains in transformants expressing various glucoamylase-gene-fusions showed that in both strains significant retention of fusion protein in the intracellular (membrane bound) fraction was observed. However, the yield of secreted recombinant protein was not affected. Results of this research will be presented and discussed.

abstract No: 

Fungal Genet. Newsl. 46 (Supl):

Full conference title: 

Fungal Genetics Conference 20th
    • Fungal Genetics Conference 20th (1999)