Probable 2-keto-3-deoxyxylonate dehydratase involved in the degradation of D-xylose, a major component of hemicelluloses such as xylan. Catalyzes the fourth reaction in the xylose utilization pathway through dehydratation of 2-dehydro-3-deoxy-D-xylonate into alpha-ketoglutarate semialdehyde (2,5-dioxopentanoate). 2-dehydro-3-deoxy-D-arabinonate = 2,5-dioxopentanoate + H2O Carbohydrate metabolism; D-xylose degradation. Transcriptionally up-regulated by both L-arabinose and D-xylose via the pentose-specific regulator XacR. Impairs growth on D-xylose as sole energy and carbon substrate. Belongs to the FAH family.