3deoxyDglyceroDgalactoNnononic

3-deoxy-D-glycero-D-manno-octulosonate, often abbreviated as KDO, is a unique sugar molecule that plays a crucial role in the structure and function of bacterial cell walls. It is a derivative of the sugar mannose, with a deoxy (oxygen-free) group at the 3rd carbon position. This modification is essential for the synthesis of lipopolysaccharides (LPS), which are major components of the outer membrane of Gram-negative bacteria.

KDO is synthesized through a series of enzymatic reactions that involve the conversion of mannose to KDO-8-phosphate, followed by the removal of the phosphate group to yield free KDO. This sugar is then incorporated into the LPS structure, where it forms a repeating unit that contributes to the rigidity and strength of the bacterial cell wall.

The presence of KDO in bacterial LPS is a key feature that distinguishes Gram-negative bacteria from other bacterial groups. It is also a target for some antibiotics, as the absence of KDO in the LPS structure can lead to the disruption of the bacterial cell wall and subsequent cell death.

In addition to its role in bacterial cell walls, KDO has been studied for its potential as a vaccine component. KDO-containing polysaccharides have been shown to induce strong immune responses and are being explored for their use in the development of new vaccines against bacterial infections.