These sequences describe 2-dehydro-3-deoxyphosphooctonate aldolase. Alternate names include 3-deoxy-d-manno-octulosonic acid 8-phosphate and KDO-8 phosphate synthetase. It catalyzes the aldol condensation of phosphoenolpyruvate with D-arabinose 5-phosphate.

phosphoenolpyruvate + D-arabinose 5-phosphate + H₂O = 2-dehydro-3-deoxy-D-octonate 8-phosphate + phosphate

In Gram-negative bacteria, this is the first step in the biosynthesis of 3-deoxy-D-manno-octulosonate, part of the oligosaccharide core of lipopolysaccharide.