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Journal of Bacteriology, August 2009, p. 5272-5282, Vol. 191, No. 16
0021-9193/09/$08.00+0     doi:10.1128/JB.00019-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Structural Analysis of the Core Region of O-Lipopolysaccharide of Porphyromonas gingivalis from Mutants Defective in O-Antigen Ligase and O-Antigen Polymerase{triangledown} ,{dagger}

Nikolay A. Paramonov, Joseph Aduse-Opoku, Ahmed Hashim, Minnie Rangarajan,* and Michael A. Curtis

Queen Mary University of London, Barts and The London School of Medicine & Dentistry, Centre for Infectious Disease, Institute of Cell and Molecular Science, 4 Newark Street, London E1 2AT, United Kingdom

Received 7 January 2009/ Accepted 2 June 2009

Porphyromonas gingivalis synthesizes two lipopolysaccharides (LPSs), O-LPS and A-LPS. Here, we elucidate the structure of the core oligosaccharide (OS) of O-LPS from two mutants of P. gingivalis W50, {Delta}PG1051 (WaaL, O-antigen ligase) and {Delta}PG1142 (O-antigen polymerase), which synthesize R-type LPS (core devoid of O antigen) and SR-type LPS (core plus one repeating unit of O antigen), respectively. Structural analyses were performed using one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy in combination with composition and methylation analysis. The outer core OS of O-LPS occurs in two glycoforms: an "uncapped core," which is devoid of O polysaccharide (O-PS), and a "capped core," which contains the site of O-PS attachment. The inner core region lacks L(D)-glycero-D(L)-manno-heptosyl residues and is linked to the outer core via 3-deoxy-D-manno-octulosonic acid, which is attached to a glycerol residue in the outer core via a monophosphodiester bridge. The outer region of the "uncapped core" is attached to the glycerol and is composed of a linear {alpha}-(1->3)-linked D-Man OS containing four or five mannopyranosyl residues, one-half of which are modified by phosphoethanolamine at position 6. An amino sugar, {alpha}-D-allosamine, is attached to the glycerol at position 3. In the "capped core," there is a three- to five-residue extension of {alpha}-(1->3)-linked Man residues glycosylating the outer core at the nonreducing terminal residue. β-D-GalNAc from the O-PS repeating unit is attached to the nonreducing terminal Man at position 3. The core OS of P. gingivalis O-LPS is therefore a highly unusual structure, and it is the basis for further investigation of the mechanism of assembly of the outer membrane of this important periodontal bacterium.

* Corresponding author. Mailing address: Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Centre for Infectious Disease, Institute of Cell and Molecular Science, 4 Newark Street, London E1 2AT, United Kingdom. Phone: 44 207 882 2320. Fax: 44 207 882 2181. E-mail: m.rangarajan{at}qmul.ac.uk

{triangledown} Published ahead of print on 12 June 2009.

{dagger} Supplemental material for this article may be found at http://jb.asm.org/.

Journal of Bacteriology, August 2009, p. 5272-5282, Vol. 191, No. 16
0021-9193/09/$08.00+0     doi:10.1128/JB.00019-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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