The CDP-abequose synthase is involved in lipopolysaccharides (LPS) synthesis containing abequose which are important antigens of the cell surface responsible for the serological O specificity. Derivatives of the 3,6-dideoxyhexose group have a particular highly immunogenic character. CDP-alpha-D-abequose + NADP(+) = CDP-4-dehydro-3,6-dideoxy-alpha-D-glucose + H(+) + NADPH Bacterial outer membrane biogenesis; LPS O-antigen biosynthesis. Belongs to the NAD(P)-dependent epimerase/dehydratase family.