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J. Biol. Chem., Vol. 280, Issue 44, 36648-36656, November 4, 2005
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1
1
2
From the
Departamento de Microbiología y Parasitología Sanitarias, Facultad de Farmacia, Universidad de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain,
Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, Diagonal 645, 08071 Barcelona, Spain, and ¶Dipartimento di Chimica Organica e Biochimica, Università Federico II di Napoli, Complesso Universitario Monte S. Angelo. Via Cyntia 4, 80126 Napoli, Italy
The core lipopolysaccharide (LPS) of Klebsiella pneumoniae is characterized by the presence of disaccharide
GlcN-(1,4)-
GalA attached by an
1,3 linkage to L-glycero-D-manno-heptopyranose II (LD-HeppII). Previously it has been shown that the WabH enzyme catalyzes the incorporation of GlcNAc from UDP-GlcNAc to outer core LPS. The presence of GlcNAc instead of GlcN and the lack of UDP-GlcN in bacteria indicate that an additional enzymatic step is required. In this work we identified a new gene (wabN) in the K. pneumoniae core LPS biosynthetic cluster. Chemical and structural analysis of K. pneumoniae non-polar wabN mutants showed truncated core LPS with GlcNAc instead of GlcN. In vitro assays using LPS truncated at the level of D-galacturonic acid (GalA) and cell-free extract containing WabH and WabN together led to the incorporation of GlcN, whereas none of them alone were able to do it. This result suggests that the later enzyme (WabN) catalyzes the deacetylation of the core LPS containing the GlcNAc residue. Thus, the incorporation of the GlcN residue to core LPS in K. pneumoniae requires two distinct enzymatic steps. WabN homologues are found in Serratia marcescens and some Proteus strains that show the same disaccharide
GlcN-(1,4)-
GalA attached by an
1,3 linkage to LD-HeppII.
Received for publication, June 9, 2005 , and in revised form, August 29, 2005.
* This work was supported by Plan Nacional de Investigación y Desarrollo and Fiondo de Investigaciones Sanitarias grants (Ministerio de Educación, Ciencia y Deporte and Ministerio de Sanidad, Spain) and from Generalitat de Catalunya. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 Supported by predoctoral fellowships from Ministerio de Ciencia y Tecnología (Spain), Universidad de Barcelona, and Generalitat de Catalunya.
2 To whom correspondence should be addressed. Tel.: 34-934021486; Fax: 34-934039047; E-mail: jtomas{at}ub.edu.
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