Isolation and characterization of two specific regulatory Aspergillus niger mutants shows antagonistic regulation of arabinan and xylan metabolism.
This paper describes two Aspergillus niger mutants (araA and araB) specifically disturbed in the regulation of the arabinanase system in response to the presence of L-arabinose. Expression of the three known L-arabinose-induced arabinanolytic genes, abfA, abfB and abnA, was substantially decreased or absent in the araA and araB strains compared to the wild-type when incubated in the presence of L-arabinose or L-arabitol. In addition, the intracellular activities of L-arabitol dehydrogenase and L-arabinose reductase, involved in L-arabinose catabolism, were decreased in the araA and araB strains. Finally, the data show that the gene encoding D-xylulose kinase, xkiA, is also under control of the arabinanolytic regulatory system. L-Arabitol, most likely the true inducer of the arabinanolytic and L-arabinose catabolic genes, accumulated to a high intracellular concentration in the araA and araB mutants. This indicates that the decrease of expression of the arabinanolytic genes was not due to lack of inducer accumulation. Therefore, it is proposed that the araA and araB mutations are localized in positive-acting components of the regulatory system involved in the expression of the arabinanase-encoding genes and the genes encoding the L-arabinose catabolic pathway.
Section Molecular Genetics of Industrial Micro-organisms, Wageningen University, Dreijenlaan 2, NL-6703HA Wageningen, The Netherlands.
Marco J L
MJL
de Groot
Section Molecular Genetics of Industrial Micro-organisms, Wageningen University, Dreijenlaan 2, NL-6703HA Wageningen, The Netherlands.
Peter J I
PJI
van de Vondervoort
Section Molecular Genetics of Industrial Micro-organisms, Wageningen University, Dreijenlaan 2, NL-6703HA Wageningen, The Netherlands.
Ronald P
RP
de Vries
Section Molecular Genetics of Industrial Micro-organisms, Wageningen University, Dreijenlaan 2, NL-6703HA Wageningen, The Netherlands.
Patricia A
PA
vanKuyk
Section Molecular Genetics of Industrial Micro-organisms, Wageningen University, Dreijenlaan 2, NL-6703HA Wageningen, The Netherlands.
George J G
GJG
Ruijter
Section Molecular Genetics of Industrial Micro-organisms, Wageningen University, Dreijenlaan 2, NL-6703HA Wageningen, The Netherlands.
Jaap
J
Visser
D001089:Arabinose / Q000378:metabolism; D001234:Aspergillus niger / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010088:Oxidoreductases / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D013402:Sugar Alcohols / Q000378:metabolism; D014990:Xylans / Q000378:metabolism*
D005656:Fungal Proteins; D011134:Polysaccharides; D013402:Sugar Alcohols; D014990:Xylans; C030080:araban; D001089:Arabinose; D010088:Oxidoreductases; D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase; C014999:arabitol