The @entity11150 D-xylulose kinase encoding gene has been cloned by complementation of a @entity6475 in D-xylulose kinase activity. Expression of xkiA was observed in the presence of @entity4583 , @entity46606 and @entity6122 . Expression of xkiA is not mediated by XLNR, the xylose-dependent positively-acting xylanolytic regulator. Although the expression of xkiA is subject to @entity505 catabolite repression, the wide domain regulator CREA is not directly involved. The A. @entity3456 D-xylulose kinase was purified to homogeneity, and the molecular mass determined using electrospray ionization mass spectrometry agreed with the calculated molecular mass of 62816.6 Da. The activity of XKIA is highly specific for D-xylulose. Kinetic parameters were determined as Km(D-xylulose) = 0.76 mM and Km( @entity855 ) = 0.061 mM. Increased transcript levels of the genes encoding @entity16148 and xylan degrading enzymes, observed in the xylulose kinase deficient strain, correlate with increased accumulation of @entity46606 and @entity8372 , respectively. This result supports the suggestion that @entity46606 may be the specific low molecular mass inducer of the genes involved in @entity16148 degradation. It also suggests a possible role for @entity8372 in the induction of xylanolytic genes. Conversely, overproduction of XKIA did not reduce the size of the intracellular @entity10499 and @entity8372 pools, and therefore had no effect on expression of genes encoding xylan and @entity16148 degrading enzymes nor on the activity of the enzymes of the catabolic pathway.

The @entity11150 D-xylulose kinase gene is co-expressed with genes encoding XXXX degrading enzymes, and is essential for growth on @entity6122 and @entity4583 .

@entity6122 :: ('MESH:D014994', 'Chemical') :: ['D-xylose'] @entity16148 :: ('MESH:C030080', 'Chemical') :: ['arabinan'] @entity8372 :: ('MESH:D014993', 'Chemical') :: ['xylitol'] @entity10499 :: ('MESH:C014999', 'Chemical') :: ['arabitol'] @entity11150 :: ('5061', 'Species') :: ['Aspergillus niger'] @entity4583 :: ('MESH:D001089', 'Chemical') :: ['L-arabinose'] @entity46606 :: ('CHEBI:18403', 'Chemical') :: ['L-arabitol'] @entity6475 :: ('MESH:D013180', 'Disease') :: ['strain deficient'] @entity3456 :: ('4230', 'Species') :: ['niger'] @entity505 :: ('MESH:D002244', 'Chemical') :: ['carbon'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity16148 :: (MESH:C030080,Chemical) :: ['arabinan']
