A polysaccharide of Alloiococcus otitidis, a new pathogen of otitis media: chemical structure and synthesis of a neoglycoconjugate thereof.
Alloiococcus otitidis is a recently discovered Gram-positive bacterium that has been linked with otitis media (middle ear infections). In this study, we describe the structure of a novel capsular polysaccharide (PS) expressed by the type-strain of A. otitidis, ATCC 51267, and the synthesis of a glycoconjugate composed of the capsule PS and bovine serum albumin (BSA). The capsule PS of A. otitidis type-strain was determined to be a repeating trisaccharide composed of 3-substituted N-acetyl-D-glucosamine (GlcpNAc), 6-substituted N-acetyl-D-galactosamine (GalpNAc), and 4-substituted D-glucuronic acid (GlcpA), of which the majority was amidically decorated with L-glutamic acid (Glu): {-->6)-beta-GalpNAc-(1-->4)-[Glup-->6]-beta-GlcpA-(1-->3)-beta-GlcpNAc-(1}n. Monomeric analysis performed on other A. otitidis strains revealed that similar components were variably expressed, but Glu appeared to be a regular constituent in all the strains examined. Due to the suitable presence of GlcpA and Glu, our approach for glycoconjugate synthesis employed a carbodiimide-based strategy with activation of available carboxyl groups by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), which afforded direct coupling between the capsule PS and BSA. Analysis by mass spectrometry indicated that this A. otitidis capsule PS-BSA conjugate was composed of BSA units that carried up to seven capsule PSs. This work represents the first report in the literature describing an A. otitidis cell-surface carbohydrate and the synthesis of a glycoconjugate preparation thereof. Presently, we are formulating plans to immunologically evaluate this A. otitidis glycoconjugate vaccine in animals.
Arar
Sharif
S
Department of Chemistry, University of Guelph, Guelph, ON, Canada N1G 2W1.
Vinogradov
Evguenii
E
Shewmaker
P Lynn
PL
Monteiro
Mario A
MA
D000818:Animals; D016667:Bacterial Capsules / Q000737:chemistry*; D002240:Carbohydrate Sequence; D002417:Cattle; D008401:Gas Chromatography-Mass Spectrometry; D006001:Glycoconjugates / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism; D006095:Gram-Positive Cocci / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010033:Otitis Media / Q000382:microbiology*; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism
D006001:Glycoconjugates; D011135:Polysaccharides, Bacterial; D012710:Serum Albumin, Bovine