The abfB gene encoding the major alpha-L-arabinofuranosidase of Aspergillus nidulans: nucleotide sequence, regulation and construction of a disruptedstrain
M. Gielkens et al., The abfB gene encoding the major alpha-L-arabinofuranosidase of Aspergillus nidulans: nucleotide sequence, regulation and construction of a disruptedstrain, MICROBIO-UK, 145, 1999, pp. 735-741
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 nuc
leotide sequence of the A. nidulans abfB gene shows strong homology with th
e A. niger abfB, Trichoderma reesei abf-1 and Trichoderma koningii alpha-L-
arabinofuranosidase/beta-xylosidase genes. Regulation of abfB expression ha
s been investigated in cultures induced with L-arabitol. The accumulation o
f abfB mRNA, total alpha-L-arabinofuranosidase activity and AbfB protein le
vels have been determined in a wild-type A. nidulans strain as well as in d
ifferent mutant strains. These strains are affected either in their respons
e to ambient ph (palA1 and pacC(c)14 mutants), carbon catabolite repression
(creA(d)4 mutant), the ability to utilize L-arabitol as a carbon source (a
raA1 mutant) or a combination of both latter genotypes (araA1 creA(d)4). Th
e results obtained indicate that the expression of the A. nidulans abfB gen
e was higher at acidic pus and was superinduced in this double mutant. Furt
hermore, disruption of the abfB gene demonstrated that in A. nidulans AbfB
is the major p-nitrophenyl alpha-L-arabinofuranoside-hydrolysing activity b
ut at least one minor activity is expressed, which is involved in the relea
se of L-arabinose from polysaccharides.