EK3D - an E. coli K antigen 3-dimensional structure database is a repository of 72 E. coli K antigens that provides information about the sugar composition, epimeric & enantiomeric forms and linkages between the sugar monomers.

The capsule is composed of high molecular weight polysaccharides non-covalently attached to the bacterial surface. It is one of the major surface associated virulence factors of the bacteria that conceals the bacterial surface and helps it in evading the host self-defense mechanisms....Read more

E. coli K antigens

E. coli is a Gram-negative bacterium that is a common cause for urinary tract infections (including kidney infections), bloodstream infection, intra-abdominal infections like peritonitis, skin & soft tissue infections, neonatal meningitis and foodborne infections. The capsular polysaccharides of E. coli have been well characterized and classified into four groups based on several factors, including biosynthetic gene locus and assembly mechanisms....Read more

Importance of studying K antigens

The development of multiple drug resistance (MDR) is one of the major problem that we face today. Certain pathogenic strains of E. coli have increasingly become resistant to many antibacterial drugs and are a major threat to public health and safety. For instance, two major drugs namely, third-generation cephalosporins and fluoroquinolones that are widely under use have become ineffective against many E. coli infections. Resistance to carbapenem, a "last resort antibiotic" has also been reported.

With the emergence of a so called "post-antibiotic era", there is a need to focus on new drug targets, such as the bacterial capsule. There are ~80 K antigens known to exist in E. coli, and deriving structural information of these antigens is difficult due to their high conformational flexibility. Structural information about these antigens would aid in the vaccine and drug discovery against E. coli infections.