The abfB gene encoding the major alpha-L-arabinofuranosidase of Aspergillus nidulans: nucleotide sequence, regulation and construction of a disrupted strain.
Using a DNA fragment containing the Aspergillus niger abfB gene as a probe, the homologous Aspergillus nidulans gene, designated abfB, has been cloned from a genomic library containing size-selected HindIII fragments. The nucleotide sequence of the A. nidulans abfB gene shows strong homology with the A. niger abfB, Trichoderma reesei abf-1 and Trichoderma koningii alpha-L-arabinofuranosidase/beta-xylosidase genes. Regulation of abfB expression has been investigated in cultures induced with L-arabitol. The accumulation of abfB mRNA, total alpha-L-arabinofuranosidase activity and AbfB protein levels have been determined in a wild-type A. nidulans strain as well as in different mutant strains. These strains are affected either in their response to ambient pH (paIA1 and pacC(c)14 mutants), carbon catabolite repression (creA(d)4 mutant), the ability to utilize L-arabitol as a carbon source (araA1 mutant) or a combination of both latter genotypes (araA1 creA(d)4). The results obtained indicate that the expression of the A. nidulans abfB gene was higher at acidic pHs and was superinduced in this double mutant. Furthermore, disruption of the abfB gene demonstrated that in A. nidulans AbfB is the major p-nitrophenyl alpha-L-arabinofuranoside-hydrolysing activity but at least one minor activity is expressed, which is involved in the release of L-arabinose from polysaccharides.
Gielkens
Marco
M
Section of Molecular Genetics of Industrial Micro-organisms, Wageningen Agricultural University, Dreijenlaan 2, NL-6703-HA Wageningen, The Netherlands.
González-Candelas
Luis
L
Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, Consejo Superior de Investigaciones Científicas, Apartado Postal 73, 46100-Burjassot, Valencia, Spain.
Sánchez-Torres
Paloma
P
Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, Consejo Superior de Investigaciones Científicas, Apartado Postal 73, 46100-Burjassot, Valencia, Spain.
van de Vondervoort
Peter
P
Section of Molecular Genetics of Industrial Micro-organisms, Wageningen Agricultural University, Dreijenlaan 2, NL-6703-HA Wageningen, The Netherlands.
de Graaff
Leo
L
Section of Molecular Genetics of Industrial Micro-organisms, Wageningen Agricultural University, Dreijenlaan 2, NL-6703-HA Wageningen, The Netherlands.
Visser
Jaap
J
Section of Molecular Genetics of Industrial Micro-organisms, Wageningen Agricultural University, Dreijenlaan 2, NL-6703-HA Wageningen, The Netherlands.
Ramón
Daniel
D
Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, Consejo Superior de Investigaciones Científicas, Apartado Postal 73, 46100-Burjassot, Valencia, Spain.
D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000201:enzymology / Q000235:genetics*; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D006026:Glycoside Hydrolases / Q000235:genetics*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase