3deoxyDmanno2octulonic

3-deoxy-D-manno-2-octulosonic acid, often abbreviated as KDO, is a non-ulosonic acid found in the lipopolysaccharide (LPS) of Gram-negative bacteria. It is a nine-carbon sugar acid that plays a crucial role in the structure and function of the bacterial outer membrane. KDO is a characteristic component of the inner core region of LPS, linking the lipid A portion to the more distal O-antigen.

The biosynthesis of KDO is an essential process for the survival of many Gram-negative bacteria, making it a potential target for antimicrobial drug development. Enzymes involved in KDO synthesis, such as KDO-8-phosphate synthase (KDOPS), have been investigated as therapeutic targets. The presence of KDO is conserved across a wide range of Gram-negative species, highlighting its fundamental importance.

KDO's unique structure, particularly the presence of a carboxylic acid group and the deoxy position, contributes to its specific interactions within the LPS molecule and with other cellular components. Its presence is integral to the integrity of the Gram-negative outer membrane, which acts as a barrier against various environmental insults. Alterations or deficiencies in KDO incorporation can lead to significant structural defects and increased susceptibility to antibiotics and host immune responses.