The ionic interaction of Klebsiella pneumoniae K2 capsule and core lipopolysaccharide

Fresno, Sandra; Jiménez, Natàlia; Izquierdo, Luís; Merino, Susana; Corsaro, Maria Michela; Castro, Cristina De; Parrilli, Michelangelo; Naldi, Teresa; Regué, Miguel; Tomás, Juan M.

doi:10.1099/mic.0.28611-0

Cited by 49 publications

(34 citation statements)

References 41 publications

(39 reference statements)

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“…This fact is similar to what has been described in K. pneumoniae, where core LPS galacturonic negative charges interact with K2 polysaccharide (10).…”

Section: Discussionsupporting

confidence: 71%

Effects of Lipopolysaccharide Biosynthesis Mutations on K1 Polysaccharide Association with the Escherichia coli Cell Surface

et al. 2012

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The presence of cell-bound K1 capsule and K1 polysaccharide in culture supernatants was determined in a series of inframe nonpolar core biosynthetic mutants from Escherichia coli KT1094 (K1, R1 core lipopolysaccharide [LPS] type) for which the major core oligosaccharide structures were determined. Cell-bound K1 capsule was absent from mutants devoid of phosphoryl modifications on L-glycero-D-manno-heptose residues (HepI and HepII) of the inner-core LPS and reduced in mutants devoid of phosphoryl modification on HepII or devoid of HepIII. In contrast, in all of the mutants, K1 polysaccharide was found in culture supernatants. These results were confirmed by using a mutant with a deletion spanning from the hldD to waaQ genes of the waa gene cluster to which individual genes were reintroduced. A nuclear magnetic resonance (NMR) analysis of core LPS from HepIII-deficient mutants showed an alteration in the pattern of phosphoryl modifications. A cell extract containing both K1 capsule polysaccharide and LPS obtained from an O-antigen-deficient mutant could be resolved into K1 polysaccharide and core LPS by column chromatography only when EDTA and deoxycholate (DOC) buffer were used. These results suggest that the K1 polysaccharide remains cell associated by ionically interacting with the phosphate-negative charges of the core LPS. Escherichia coli K1 is a facultative pathogen responsible for severe extraintestinal diseases such as sepsis, meningitis, cystitis, pyelonephritis, cellulitis, pneumonia, and postoperative infections. The production of a polysialic acid K1 capsule, a homopolymer of 5-acetamido-3,5-dideoxy-D-glycero-D-galacto-non-2-ulosonic or N-acetylneuraminic acid (Neu5Ac) residues connected by ␣2-8 linkage (24) with a phase-variable O-acetylation at position 7 or 9, is the common pathogenic feature of these strains (29). The immunological tolerance of the K1 capsule by molecular mimicry to the host's own polysialic antigen (oncofetal modification of the neural cell adhesion molecule [NCAM]) impedes the development of effective vaccines to prevent diseases caused by the K1 strain.On the basis of capsule biosynthesis and assembly features, the E. coli capsules have been classified into four groups. The K1 capsule is, together with the K5 capsule, the model system for group 2 E. coli capsules (36). As in other members of group 2, the genes directing the biosynthesis of K1 capsule are organized in three distinct functional regions: region 1, kpsFE-DUCS; region 2, neuDBACES, and region 3, kpsMT. Region 2 genes appear to be K-serotype specific and are involved in K1 biosynthesis while regions 1 and 3 appear to be involved in K1 transport and are conserved among members of the E. coli group 2.Currently, it is thought that the first committed step in the biosynthesis of the K1 polysaccharide (K1-PS) is catalyzed by the epimerase NeuC leading to the formation of N-acetylmannosamine (ManNAc) from UDP-N-acetylglucosamine (UDPGlcNAc), followed by the synthesis of CMP-N-acetylneuraminic (CMP-Neu5Ac) acid from ManNAc ...

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“…This fact is similar to what has been described in K. pneumoniae, where core LPS galacturonic negative charges interact with K2 polysaccharide (10).…”

Section: Discussionsupporting

confidence: 71%

Effects of Lipopolysaccharide Biosynthesis Mutations on K1 Polysaccharide Association with the Escherichia coli Cell Surface

et al. 2012

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“…Likewise we speculate that APs would release CPS from the surface by disturbing cationdependent ionic bridges between adjacent molecules of CPS. Interestingly, it has been shown that CPS from K. pneumoniae is associated with the cell surface by an ionic interaction between CPS and the LPS core region (Fresno et al, 2006). This interaction is stabilized by divalent cations (Fresno et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

“…Interestingly, it has been shown that CPS from K. pneumoniae is associated with the cell surface by an ionic interaction between CPS and the LPS core region (Fresno et al, 2006). This interaction is stabilized by divalent cations (Fresno et al, 2006). In this context, it is not surprising that polymyxin B released more CPS from the bacterial surface than HNP-1 (Table 2) because polymyxin B is considered the most potent AP disturbing cation-dependent ionic bridges between LPS molecules (Vaara, 1992).…”

Section: Discussionmentioning

confidence: 99%

Capsule polysaccharide is a bacterial decoy for antimicrobial peptides

2008

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Antimicrobial peptides (APs) are important host weapons against infections. Nearly all APs are cationic and their microbicidal action is initiated through interactions with the anionic bacterial surface. It is known that pathogens have developed countermeasures to resist these agents by reducing the negative charge of membranes, by active efflux and by proteolytic degradation. Here we uncover a new strategy of resistance based on the neutralization of the bactericidal activity of APs by anionic bacterial capsule polysaccharide (CPS). Purified CPSs from Klebsiella pneumoniae K2, Streptococcus pneumoniae serotype 3 and Pseudomonas aeruginosa increased the resistance to polymyxin B of an unencapsulated K. pneumoniae mutant. Furthermore, these CPSs increased the MICs of polymyxin B and human neutrophil a-defensin 1 (HNP-1) for unencapsulated K. pneumoniae, Escherichia coli and P. aeruginosa PAO1. Polymyxin B or HNP-1 released CPS from capsulated K. pneumoniae, S. pneumoniae serotype 3 and P. aeruginosa overexpressing CPS. Moreover, this material also reduced the bactericidal activity of APs. We postulate that APs may trigger in vivo the release of CPS, which in turn will protect bacteria against APs. We found that anionic CPSs, but not cationic or uncharged ones, blocked the bactericidal activity of APs by binding them, thereby reducing the amount of peptides reaching the bacterial surface. Supporting this, polycations inhibited such interaction and the bactericidal activity was restored. We postulate that trapping of APs by anionic CPSs is an additional selective virulence trait of these molecules, which could be considered as bacterial decoys for APs.

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“…Next, we investigated the ability of the lipid A pattern found in vivo to stimulate inflammatory responses. For these experiments, lipid A was purified from Kp52145 and 52145-ΔlpxO isogenic capsule mutants (hereafter WT* and lpxO*, respectively) to avoid the copurification of the capsule polysaccharide with the LPS (23). Lipid A was also purified from the lpxO complemented strain (52145-Δwca K2 -ΔlpxOCom; lpxO*Com).…”

Section: Significancementioning

confidence: 99%

Deciphering tissue-induced Klebsiella pneumoniae lipid A structure

Llobet

Martínez-Moliner

Moranta

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

134

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The outcome of an infection depends on host recognition of the pathogen, hence leading to the activation of signaling pathways controlling defense responses. A long-held belief is that the modification of the lipid A moiety of the lipopolysaccharide could help Gram-negative pathogens to evade innate immunity. However, direct evidence that this happens in vivo is lacking. Here we report the lipid A expressed in the tissues of infected mice by the human pathogen Klebsiella pneumoniae. Our findings demonstrate that Klebsiella remodels its lipid A in a tissue-dependent manner. Lipid A species found in the lungs are consistent with a 2-hydroxyacyl-modified lipid A dependent on the PhoPQ-regulated oxygenase LpxO. The in vivo lipid A pattern is lost in minimally passaged bacteria isolated from the tissues. LpxO-dependent modification reduces the activation of inflammatory responses and mediates resistance to antimicrobial peptides. An lpxO mutant is attenuated in vivo thereby highlighting the importance of this lipid A modification in Klebsiella infection biology. Colistin, one of the last options to treat multidrug-resistant Klebsiella infections, triggers the in vivo lipid A pattern. Moreover, colistin-resistant isolates already express the in vivo lipid A pattern. In these isolates, LpxO-dependent lipid A modification mediates resistance to colistin. Deciphering the lipid A expressed in vivo opens the possibility of designing novel therapeutics targeting the enzymes responsible for the in vivo lipid A pattern.

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The ionic interaction of Klebsiella pneumoniae K2 capsule and core lipopolysaccharide

Cited by 49 publications

References 41 publications

Effects of Lipopolysaccharide Biosynthesis Mutations on K1 Polysaccharide Association with the Escherichia coli Cell Surface

Effects of Lipopolysaccharide Biosynthesis Mutations on K1 Polysaccharide Association with the Escherichia coli Cell Surface

Capsule polysaccharide is a bacterial decoy for antimicrobial peptides

Deciphering tissue-induced Klebsiella pneumoniae lipid A structure

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