* The authors dedicate this review to Dr. Malcolm Perry in our admiration of the impact that he has made to the field of complex carbohydrate research during his long and fruitful career at the National Research Council of Canada.
** To whom correspondence should be addressed.
Received January 15, 2011; Revision received February 1, 2011
Pseudomonas aeruginosa is a Gram-negative bacterium that is ubiquitous in the environment and generally considered to be a saprophyte, but it is also an important opportunistic human pathogen. Pseudomonas aeruginosa elaborates a variety of virulence factors, one of which is lipopolysaccharide (LPS). LPS of P. aeruginosa is composed of three distinct regions: lipid A, core oligosaccharide (OS), and the long-chain O antigen. The core OS of P. aeruginosa is composed of L-glycero-D-manno-heptose, 3-deoxy-D-manno-oct-2-ulosonic acid, D-galactosamine, D-glucose, and L-rhamnose. Non-carbohydrate substituents are also found in the core OS including phosphate, 2-aminoethyl (di)phosphate, acetyl, alanyl and carbamoyl groups. Pseudomonas aeruginosa simultaneously synthesizes two core glycoforms, namely, capped and uncapped core. The capped core is covalently attached to an O antigen, whereas the uncapped core is devoid of O antigen. Although the core of P. aeruginosa LPS is relatively conserved, strain-to-strain variability of its structure exists. This includes phosphorylation pattern, the level of O-acetylation, and the presence or absence of a fourth glucose residue at the distal end of the uncapped core. A number of studies have been reported on the structures of unique truncated core OS with unusual modifications. This mini-review summarizes the diversity of P. aeruginosa complete and truncated core OS structures published over the past fifteen years.
KEY WORDS: lipopolysaccharide, core oligosaccharide, Pseudomonas aeruginosa