The Incorporation of Glucosamine into Enterobacterial Core Lipopolysaccharide

Abstract

The core lipopolysaccharide (LPS) of Klebsiella pneumoniae is characterized by the presence of disaccharide αGlcN-(1,4)-αGalA attached by an α1,3 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 αGlcN-(1,4)-αGalA attached by an α1,3 linkage to ld-HeppII. The core lipopolysaccharide (LPS) of Klebsiella pneumoniae is characterized by the presence of disaccharide αGlcN-(1,4)-αGalA attached by an α1,3 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 αGlcN-(1,4)-αGalA attached by an α1,3 linkage to ld-HeppII. Klebsiella pneumoniae is an important nosocomial pathogen (1Emori T.G. Gaynes R.P. Clin. Microbiol. Rev. 1993; 6: 428-442Crossref PubMed Scopus (1040) Google Scholar) causing infections that may occur at almost all body sites with highest incidence in the urinary and the respiratory tracts. The main populations at risk are neonates, immunocompromised hosts, and patients predisposed by surgery, diabetes, malignancy, etc. (1Emori T.G. Gaynes R.P. Clin. Microbiol. Rev. 1993; 6: 428-442Crossref PubMed Scopus (1040) Google Scholar, 2Hansen D.S. Gottschau A. Holmes K.J. J. Hosp. Infect. 1997; 37: 119-132Google Scholar, 3Hervás J.A. Alomar A. Salvá F. Reina J. Benedí V.J. Clin. Infect. Dis. 1993; 16: 719-724Crossref PubMed Scopus (54) Google Scholar, 4Hansen D.S. Mestre F. Albertí S. Hernández-Alles S. Alvarez D. Domenech-Sánchez A. Gil J. Merino S. Tomás J.M. Benedí V.J. J. Clin. Microbiol. 1999; 37: 56-62Crossref PubMed Google Scholar). K. pneumoniae typically express both smooth lipopolysaccharide (LPS) 3The abbreviations used are:LPSlipopolysaccharideGalAd-galacturonic acidHepheptoseld-Hepl-glycero-d-manno-heptoseld-Heppl-glycero-d-manno-heptopyranoseKdo3-deoxy-d-manno-oct-2-ulosonic acidMALDI-TOFmatrix-assisted laser desorption ionization time-of-flightMSmass spectrometryORFopen reading frameOSoligosaccharideTricineN-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine. and capsule polysaccharide (K-antigen) on its surface, and both antigens (LPS and capsule) contribute to the pathogenesis of this species. lipopolysaccharide d-galacturonic acid heptose l-glycero-d-manno-heptose l-glycero-d-manno-heptopyranose 3-deoxy-d-manno-oct-2-ulosonic acid matrix-assisted laser desorption ionization time-of-flight mass spectrometry open reading frame oligosaccharide N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine. As in other Enterobacteriaceae in the K. pneumoniae LPS three domains are recognized: the highly conserved and hydrophobic lipid A, the hydrophilic and highly variable O-antigen polysaccharide, and the core oligosaccharide (OS) connecting lipid A and O-antigen. The core domain is usually divided into inner and outer core on the basis of sugar composition. The K. pneumoniae core LPS structure has been determined for several O-serotypes. Although the inner core is highly conserved within the Enterobacteriaceae the K. pneumoniae inner core differs from those of Escherichia coli and Salmonella by the lack of l-glycero-d-manno-heptopyranose I and II (ld-HeppI and -II) phosphoryl modifications and by the presence of a d-glucose (Glc) residue linked by a β1,4 bond to ld-HeppI (5Vinogradov E. Perry M.B. Carbohydr. Res. 2001; 335: 291-296Crossref PubMed Scopus (55) Google Scholar, 6Vinogradov E. Cedzynski M. Ziolkowski A. Swierzko A. Eur. J. Biochem. 2001; 268: 1722-1729Crossref PubMed Scopus (30) Google Scholar, 7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar). Two outer core types (1 and 2) were described in K. pneumoniae, both containing the disaccharide αGlcN-(1,4)-αGalA attached by an α1,3 linkage to ld-HeppII (5Vinogradov E. Perry M.B. Carbohydr. Res. 2001; 335: 291-296Crossref PubMed Scopus (55) Google Scholar, 6Vinogradov E. Cedzynski M. Ziolkowski A. Swierzko A. Eur. J. Biochem. 2001; 268: 1722-1729Crossref PubMed Scopus (30) Google Scholar, 7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar). Type 1 core contains a 3-deoxyd-manno-oct-2-ulosonic acid (Kdo) residue linked by an α2,6 bond to the GlcN residue (5Vinogradov E. Perry M.B. Carbohydr. Res. 2001; 335: 291-296Crossref PubMed Scopus (55) Google Scholar, 6Vinogradov E. Cedzynski M. Ziolkowski A. Swierzko A. Eur. J. Biochem. 2001; 268: 1722-1729Crossref PubMed Scopus (30) Google Scholar), whereas type 2 core contains the disaccharide βGlc-(1,6)-αGlc linked by a α1,4 bond to the GlcN residue (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar) (Fig. 1). The genes involved in the K. pneumoniae core LPS biosynthesis are clustered in a region (wa) of the K. pneumoniae chromosome, and two different clusters have been identified to be responsible for type 1 and type 2 core biosynthesis (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar, 8Regué M. Climent N. Abitiu N. Coderch N. Merino S. Izquierdo L. Altarriba M. Tomás J.M. J. Bacteriol. 2001; 183: 3564-3573Crossref PubMed Scopus (55) Google Scholar) (Fig. 1). Furthermore the functions in both inner and outer core biosynthesis of most of the transferases encoded by the wa gene products have been elucidated (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar, 8Regué M. Climent N. Abitiu N. Coderch N. Merino S. Izquierdo L. Altarriba M. Tomás J.M. J. Bacteriol. 2001; 183: 3564-3573Crossref PubMed Scopus (55) Google Scholar, 9Izquierdo L. Merino S. Coderch N. Regué M. Tomás J.M. FEMS Microbiol. Lett. 2002; 216: 211-216PubMed Google Scholar, 10Izquierdo L. Abitiu N. Coderch N. Hita B. Merino S. Gavín R. Tomás J.M. Regué M. Microbiology. 2002; 148: 3485-3496Crossref PubMed Scopus (36) Google Scholar, 11Izquierdo L. Coderch N. Piqué N. Bedini E. Corsaro M. Merino S. Fresno S. Tomas J.M. Regué M. J. Bacteriol. 2003; 185: 7213-7221Crossref PubMed Scopus (72) Google Scholar, 12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar) (Fig. 1). Nevertheless the mechanism leading to the incorporation of the outer core GlcN residue remains unknown. In searching for a candidate glucosaminyltransferase the wabH gene product was characterized (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). The WabH protein catalyzes the incorporation of GlcNAc from UDP-GlcNAc into outer core LPS. This transferase activity is dependent on the presence of the outer core d-galacturonic acid (GalA) residue in the acceptor core LPS (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). But because GlcN instead of GlcNAc is found in the K. pneumoniae outer core either an unknown glucosaminyltransferase remains to be identified or a mechanism to deacetylate the WabH-transferred GlcNAc residue should be involved. In this work we report the identification and characterization of such a core activity in K. pneumoniae and Serratia marcescens the outer core disaccharide and strains and used in this are shown in strains were in and in Scholar). was with and strains and or or pneumoniae type J.M. J. Infect. PubMed Google L. Coderch N. Piqué N. Bedini E. Corsaro M. Merino S. Fresno S. Tomas J.M. Regué M. J. Bacteriol. 2003; 185: 7213-7221Crossref PubMed Scopus (72) Google wabN wabH non-polar wabN non-polar wabH type F. Microbiol. Scopus Google M. Climent N. Abitiu N. Coderch N. Merino S. Izquierdo L. Altarriba M. Tomás J.M. J. Bacteriol. 2001; 183: 3564-3573Crossref PubMed Scopus (55) Google wabN wabH non-polar wabN non-polar wabN coli D. J. Biol. PubMed Scopus Google D. J. Bacteriol. 1997; PubMed Scopus Google an wabN from an wabN from an wabH from an wabH from containing the containing the containing the D. J. J. Bacteriol. PubMed Scopus Google WabN from WabN from WabH from WabH from in a new were described J. T. A Scholar). E. coli and were used by the pneumoniae and genes were by in vitro of gene D. J. Bacteriol. 1997; PubMed Scopus Google Scholar). gene was to the by using the containing the D. J. Bacteriol. 1997; PubMed Scopus Google Scholar). were in wabH and The containing the and were into K. pneumoniae and by were on in containing and of the of The were by of the in The was by using and and The sites of and were contains from to the of the of to contains from to the wabN and were at region in and and by a using and The product was into and into E. coli and on at to The was by using and and The sites of and were contains from to the of the of to contains from to the wabN and were at region in and and by a using and The product was into and into E. coli and on at to The was using and and The sites of and were contains from to the of the of to contains from to the wabH and were at region in and and by a using and The product was into and into E. coli and on at to of the and strains and the and were used to for and gene the wabN genes from K. pneumoniae strains and and S. marcescens were by using and into gene was from the and D. J. J. Bacteriol. PubMed Scopus Google Scholar). from the was by in containing and was by to a of a was for at in with and were in and an of was and the were for 2 were in The wabH gene was from K. pneumoniae with and a The product was with and and to the same sites in to (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). The wabH was from K. pneumoniae with (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar) and a The product was with and and to the same sites in to a containing the wabN gene was from K. pneumoniae with and This was used to an with and This was with and to a that was to the same sites in was by of a from using and and This was used to an with and This was with and with to a This was to and was by of a from N. Piqué N. B. Abitiu N. Merino S. Izquierdo L. N. Tomás J.M. Regué M. J. Bacteriol. 2004; PubMed Scopus Google Scholar) using and This was with and and into the same sites in wabN was to and into E. coli LPS and was from of K. pneumoniae in The C. Eur. J. Biochem. PubMed Scopus Google Scholar) was used for strains whereas the K. Carbohydr. Chem. Scholar) was used for the strains the O-antigen domain LPS was of J. Bacteriol. PubMed Google Scholar). LPS were by or and by described E. J. Bacteriol. PubMed Google Scholar, Biochem. PubMed Scopus Google Scholar). of LPS was in acid for and the was by for and to lipid A of The was to in and of and were on an with a and an inner 1 analysis was with the for at for the for 1 at at at for and (1 was and with 1 (1 at for to both and acid composition. The was with the two were a of and with at for The was with and were into the and acid were in the whereas the were in the were on a of K. pneumoniae and wabN core in at with a with a in the at K. and time-of-flight mass were on a with a was was was and was were at a of by from a was using an of The was in steps. was with a from A of acid in in at a of was used the of was on the by of 1 of the The were to at were and using the core oligosaccharide (1 from was with and F. Carbohydr. Res. Scopus Google Scholar). analysis was The was with by acid to by of with and described J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). of LPS K. pneumoniae strains and were used to the WabH and WabN of strains and and were and described The were with and were in and on a of 2 using by and the were by at for was by and protein of cell-free were determined using the by the LPS of of WabN to the deacetylation of LPS was by using LPS from in a containing both and cell-free The was on the GlcNAc transferase described for WabH (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). using UDP-GlcNAc the were in at a of containing 1 and of LPS the The was by of of the cell-free from and As containing cell-free of were The were at for 2 and the were by of and for in was to a of and for at The products were by was used the were in a of at a of containing 1 of and of the cell-free The were by of of activity of were at for 2 and were by 2 of in and at for 2 The LPS was by at for and in of The LPS was with 2 of in this step was three to the The LPS was by in and to for The from the LPS were by with The were by using and of a LPS the Enterobacteriaceae the genes for involved in core LPS biosynthesis are usually found clustered in a region gene with the of two different clusters of the wa gene clusters from Enterobacteriaceae a level of gene with the different In and genes is in the K. pneumoniae 1 and 2 wa gene of of unknown are of the The analysis of this region in a acid open reading frame that a gene a in type 2 core this gene was The region was using A and and K. pneumoniae and the was in and into E. coli was used in an in vitro with As a the was The were by a with a mass of The wabN gene is to the and the of wabN is from In a wabN homologues were found in K. pneumoniae 1 and in S. marcescens (Fig. 1). The wabN was and of genes and The S. marcescens was found and protein homologues were found in Proteus and WabN and of acid and (Fig. identified a domain by the J. K. R. C. J. Biol. 2001; PubMed Scopus Google Scholar). of wabN the of the wabN gene in core LPS biosynthesis non-polar wabN were by an D. J. Bacteriol. 1997; PubMed Scopus Google Scholar). The in vitro wabN were by and to type K. pneumoniae strains and and to strains and mutants were by of the using and and characterization of the of the on core LPS biosynthesis was by LPS and analysis by both and The A region of LPS from strains and and wabN mutants LPS from type strains and (Fig. This suggests that the wabN the of or sugar from the In LPS from strains and O-antigen polysaccharide (Fig. The K. pneumoniae O-antigen polysaccharide is linked to outer core residue in type core 1 E. E. Perry M.B. Whitfield C. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar) and to the residue in type core 2 (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar), that the in the wabN mutants in the main core LPS The wabN from was into and type LPS and O-antigen polysaccharide (Fig. K. pneumoniae wabN homologues and the wabN in either of the two or (Fig. The S. marcescens wabN in the K. pneumoniae wabN mutants (Fig. the presence of a new gene by K. pneumoniae and S. marcescens an enzymatic activity for core LPS of the K. pneumoniae wabN the core LPS by the wabN LPS was from by the and C. Eur. J. Biochem. PubMed Scopus Google Scholar). analysis by of the presence of and acid shown by the In this the at and to and the presence of core In the at was in with the mass of a structure with three two and The at and were by the with at and it be that this oligosaccharide is truncated in to the core structure (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar) at the level of is this a was This is by of and B. J. Scopus Google Scholar) in to some from the at the at was to a by a at and at it was to some from them by from the at are two at and were from the of and was from the has a and a and a GlcNAc are with the core oligosaccharide structure in and of core from K. pneumoniae that are and the described are to with containing a bond a at or have been described for LPS that are in the presence of acid that are and the described are to with containing a bond a at or have been described for LPS that are in the presence of acid that are and the described are to with containing a bond a at or have been described for LPS that are in the presence of acid that are and the described are to with containing a bond a at or have been described for LPS that are in the presence of acid that are and the described are to with containing a bond a at or have been described for LPS that are in the presence of acid J. J. 1999; PubMed Scopus Google Scholar). in a new of from of of core from K. pneumoniae wabN in the the used to the is that by and the The used to the is that by and B. J. Scopus Google Scholar). in a new this a analysis on the core oligosaccharide was the were in with the In the and the GlcNAc the presence of the disaccharide and were The core structure of the was by the of its with that of the core structure of (Fig. (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar). In the presence of an at (Fig. to the of an the of the GlcN residue. In the of the region the lack of the and the the and the of the other the to be the same those of the region of (Fig. and of wabH a K. pneumoniae wabH was by of a non-polar in a type 1 core LPS (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). This in the of an in the Although this is to be of on in the of the be Furthermore this in a the of this to additional Thus, we to the and to wabH in both core types 1 and 2 of LPS from and that core from and were of O-antigen The core from wabH by acid was by The at was in with the mass of the structure Thus, the wabH the of the core the outer core residue in 1). LPS core structure determined from wabN the two outer core and GlcNAc instead of GlcN. the same core structure is the result of the WabH protein activity (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). The WabH protein catalyzes the of GlcNAc to outer core from UDP-GlcNAc (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). The presence of a domain to the in the WabN protein suggests that it be responsible for the deacetylation of the core LPS this two in vitro assays were The of the in LPS from wabN and The LPS the two outer core containing core to GlcN (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar). The in two LPS is to the in LPS from wabN from LPS This is in the described for WabH (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar) using UDP-GlcNAc and LPS from wabH acceptor and using the enzyme cell-free from K. pneumoniae strains wabH and wabN the WabH and WabN As cell-free from strains wabH and wabN were analysis of products by extract from wabH showed lipid A core in to the acceptor LPS from described (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar) (Fig. from the containing both wabH and wabN to the same LPS from (Fig. containing wabH extract alone wabN and containing wabN extract the acceptor LPS. The in vitro the of GlcN into acceptor LPS from acid and of the The with extract from wabH the of GlcNAc whereas the containing both wabH and wabN showed GlcN (Fig. In using wabH wabN or wabN extract GlcNAc GlcN was into the acceptor LPS (Fig. indicate that the GlcNAc residue to core LPS by the WabH protein is by the WabN The deacetylation step is for core by of the two outer core identified a gene involved in K. pneumoniae core of LPS from non-polar wabN in K. pneumoniae strains either type 1 or type 2 core that are truncated and that the GlcNAc the type GlcN residue. In wabH mutants were in strains type 1 and type 2 core LPS by Chemical characterization by mass spectrometry of LPS from wabH mutants showed that truncated core to the residue shown for a type 1 core LPS (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). has been shown that the WabH enzyme catalyzes the in vitro incorporation of GlcNAc from UDP-GlcNAc into core LPS truncated at the level of the residue (12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). the GlcN residue is into outer core the functions of the genes of the K. pneumoniae wa gene clusters were (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar, 8Regué M. Climent N. Abitiu N. Coderch N. Merino S. Izquierdo L. Altarriba M. Tomás J.M. J. Bacteriol. 2001; 183: 3564-3573Crossref PubMed Scopus (55) Google Scholar, 10Izquierdo L. Abitiu N. Coderch N. Hita B. Merino S. Gavín R. Tomás J.M. Regué M. Microbiology. 2002; 148: 3485-3496Crossref PubMed Scopus (36) Google Scholar, 11Izquierdo L. Coderch N. Piqué N. Bedini E. Corsaro M. Merino S. Fresno S. Tomas J.M. Regué M. J. Bacteriol. 2003; 185: 7213-7221Crossref PubMed Scopus (72) Google Scholar, 12Frirdich E. Vinogradov E. Whitfield C. J. Biol. Chem. 2004; 279: 27928-27940Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). In both the lipid A and biosynthesis a GlcNAc residue is from UDP-GlcNAc and later to GlcN PubMed Scopus Google and Whitfield C. Rev. Biochem. 2002; PubMed Scopus Google Scholar). the core LPS structure in vitro by the WabH enzyme is found in wabN mutants we a for This was by in vitro using LPS from and containing or both The K. pneumoniae outer core disaccharide αGlcN-(1,4)-αGalA linked by an α1,3 bond to ld-HeppII is found in S. marcescens N. Piqué N. B. Abitiu N. Merino S. Izquierdo L. N. Tomás J.M. Regué M. J. Bacteriol. 2004; PubMed Scopus Google and Proteus and Proteus strains and a E. J. Chem. 2002; Google Scholar). Thus, it is that strains and wabN This has been shown for S. marcescens gene homologues are able to the K. pneumoniae mutants shown in this and work (7Regué M. Izquierdo L. Fresno S. Piqué N. Corsaro M. Naldi T. De Castro C. Waidelich D. Merino S. Tomás J.M. J. Bacteriol. 2005; 187: 4198-4206Crossref PubMed Scopus (48) Google Scholar, 11Izquierdo L. Coderch N. Piqué N. Bedini E. Corsaro M. Merino S. Fresno S. Tomas J.M. Regué M. J. Bacteriol. 2003; 185: 7213-7221Crossref PubMed Scopus (72) Google Scholar, N. Piqué N. B. Abitiu N. Merino S. Izquierdo L. N. Tomás J.M. Regué M. J. Bacteriol. 2004; PubMed Scopus Google Scholar). three genes are found in In E. C. L. C. A. S. S. C. M. E. R. S. S. C. A. K. R. M. N. A. F. 2005; Scopus Google Scholar) contains and wabN that it has a core LPS of the K. pneumoniae work for the the biosynthesis of the K. pneumoniae core LPS and suggests that the three genes wabH and wabN be used to containing the disaccharide αGlcN-(1,4)-αGalA linked to inner core Furthermore the lack of UDP-GlcN in PubMed Scopus Google Scholar), the in K. pneumoniae, and the by the S. marcescens wabN led to that this be a mechanism in the biosynthesis of core GlcNAc residue is and later to The shown by the WabN homologues to of the J. K. R. C. J. Biol. 2001; PubMed Scopus Google Scholar) and to of this the of for lipid A, and core The for K. pneumoniae be to in other core containing GlcN in different for