scholarly journals Lex2B, a Phase-Variable Glycosyltransferase, Adds either a Glucose or a Galactose to Haemophilus influenzae Lipopolysaccharide

2009 ◽  
Vol 77 (6) ◽  
pp. 2376-2384 ◽  
Author(s):  
M. E. Deadman ◽  
P. Hermant ◽  
M. Engskog ◽  
K. Makepeace ◽  
E. R. Moxon ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Respiratory Tract Infections ◽  
Inner Core ◽  
Biological Properties ◽  
Single Amino Acid ◽  
Phase Variable ◽  
Killing Effect ◽  
Variable Expression ◽  
Serotype B ◽  
Tract Infections

ABSTRACT Nontypeable Haemophilus influenzae is a commensal that frequently causes otitis media and respiratory tract infections. The lex2 locus encodes a glycosyltransferase that is phase variably expressed and contributes to the significant intrastrain heterogeneity of lipopolysaccharide (LPS) composition in H. influenzae. In serotype b strains, Lex2B adds the second β-glucose in the oligosaccharide extension from the proximal heptose of the triheptose inner core backbone; this extension includes a digalactoside that plays a role in resistance of the bacteria to the killing effect of serum. As part of our studies of the structure and genetics of LPS in nontypeable H. influenzae, we show here that there are allelic polymorphisms in the lex2B sequence that correlate with addition of either a glucose or a galactose to the same position in the LPS molecule across strains. Through exchange of lex2 alleles between strains we show that alteration of a single amino acid at position 157 in Lex2B appears to be sufficient to direct the alternative glucosyl- or galactosyltransferase activities. Allelic exchange strains express LPS with altered structure and biological properties compared to the wild-type LPS. Thus, Lex2B contributes to both inter- and intrastrain LPS heterogeneity through its polymorphic sequences and phase-variable expression.

The role of lex2 in lipopolysaccharide biosynthesis in Haemophilus influenzae strains RM7004 and RM153

Microbiology ◽  
2003 ◽  
Vol 149 (11) ◽  
pp. 3165-3175 ◽  
Author(s):  
Ruth Griffin ◽  
Andrew D. Cox ◽  
Katherine Makepeace ◽  
James C. Richards ◽  
E. Richard Moxon ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Inner Core ◽  
Phase Variable ◽  
Specific Monoclonal Antibody ◽  
Variable Expression ◽  
Sequence Identity ◽  
Lipopolysaccharide Biosynthesis ◽  
Serotype B ◽  
Reading Frames

The locus lex2, comprising lex2A and lex2B, contributes to the phase-variable expression of lipopolysaccharide (LPS) of Haemophilus influenzae and was found to be present in 74 % of strains investigated. lex2A contains 5′-GCAA repeats which vary in number from 4 to 46 copies between strains. The locus was cloned from the serotype b strains RM7004 and RM153 and showed >99 % nucleotide sequence identity between these strains and the published lex2 sequence. Disruption of the lex2B gene in strain RM7004 resulted in truncation of some LPS glycoforms, shown by gel fractionation, with only one glycoform reacting with a digalactoside-specific monoclonal antibody, 4C4, compared with four LPS glycoforms in the more elongated LPS of the parent strain. Mass spectrometry and NMR analyses of LPS from the lex2B mutant revealed loss of the terminal digalactoside as well as the second β-glucose extending from the first heptose of the inner core. The authors conclude that Lex2B is the β-(1-4)-glucosyltransferase that adds the second β-glucose to the first β-glucose as part of the oligosaccharide extension from the first heptose of the LPS of strain RM7004. Investigation of the expression of the lex2 locus indicated that the genes are co-transcribed and that both reading frames are required for addition of this second β-glucose in a phase-variable manner.

scholarly journals Elucidation of the Monoclonal Antibody 5G8-Reactive, Virulence-Associated Lipopolysaccharide Epitope of Haemophilus influenzae and Its Role in Bacterial Resistance to Complement-Mediated Killing

2005 ◽  
Vol 73 (4) ◽  
pp. 2213-2221 ◽  
Author(s):  
Ruth Griffin ◽  
Andrew D. Cox ◽  
Katherine Makepeace ◽  
James C. Richards ◽  
E. Richard Moxon ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Haemophilus Influenzae ◽  
Bacterial Resistance ◽  
Inner Core ◽  
Phase Variation ◽  
Phase Variable ◽  
Type B ◽  
Variable Expression ◽  
Virulent Type ◽  
Unknown Structure

ABSTRACT The phase-variable locus lex2 is required for expression of a Haemophilus influenzae lipopolysaccharide (LPS) epitope of previously unknown structure. This epitope, which is reactive with monoclonal antibody (MAb) 5G8, has been associated with virulence of type b strains. When strain RM118 (from the same source as strain Rd), in which the lex2 locus and MAb 5G8 reactivity are absent, was transformed with lex2 DNA, transformants that were reactive with MAb 5G8 were obtained. Surprisingly, the 5G8 reactivity of these transformants was phase variable, although the lex2 locus lacked tetrameric repeats and was constitutively expressed. This phase variation was shown to be the result of phase-variable expression of phosphorylcholine (PCho) such that MAb 5G8 reacted only in the absence of PCho. Structural analysis showed that, compared to RM118, the lex2 transformant had acquired a tetrasaccharide, Gal-α1,4-Gal-β1,4-Glc-β1,4-Glc-β1,4, linked to the proximal heptose (HepI). A terminal GalNAc was detected in a minority of glycoforms. LPS derived from a mutant of RM7004, a virulent type b strain which naturally expresses lex2 and has LPS containing the same tetrasaccharide linked to HepI as the sole oligosaccharide extension from the inner core, confirmed that GalNAc is not a part of the MAb 5G8-reactive epitope. Thus, MAb 5G8 specifically binds to the structure Gal-α1,4-Gal-β1,4-Glc-β1,4-Glc-β attached via a 1,4 linkage to HepI of H. influenzae LPS, and we show that the ability to synthesize this novel tetrasaccharide was associated with enhanced bacterial resistance to complement-mediated killing.

Structural elucidation of lipopolysaccharide core oligosaccharides from lic1 and lic1/lic2 mutants of Haemophilus influenzae type b strain Eagan

2008 ◽  
Vol 54 (4) ◽  
pp. 281-290 ◽  
Author(s):  
Hussein Masoud ◽  
E. Richard Moxon ◽  
James C. Richards
Keyword(s):  
Haemophilus Influenzae ◽  
Inner Core ◽  
Transcriptional Unit ◽  
Haemophilus Influenzae Type ◽  
Resonance Spectroscopy ◽  
Ionization Mass ◽  
Haemophilus Influenzae Type B ◽  
Phase Variable ◽  
Type B ◽  
Variable Expression

The structures of lipopolysaccharides (LPSs) of lic1 and lic1/lic2 mutants from Haemophilus influenzae type b strain Eagan (RM153) were investigated using methylation analysis, electrospray ionization – mass spectrometry, and nuclear magnetic resonance spectroscopy on O-deacylated, O- and N-deacylated core oligosaccharide (OS); and deacylated, dephosphorylated, and terminally reduced samples. The backbone OS derived from the major LPS glycoforms were determined to consist of the inner-core triheptosyl unit, l-α-d-Hepp-(1-2)-l-α-d-Hepp-(1-3)-l-α-d-Hepp-(1-, common to all H. influenzae strains investigated to date that is linked to the lipid A region of the molecule via a Kdo residue to which β-d-Glcp and β-d-Galp residues are attached in 1,4 and 1,2 linkages to the proximal (HepI) and distal (HepIII) heptose residues, respectively. It was found that the lic1 mutant predominately elaborates the Hex4 LPS glycoforms previously identified in the parent strain where a β-d-Glcp-(1-4)-α-d-Glcp unit is linked in a 1,3 linkage to the central heptose (HepII) of the triheptosyl moiety. The lic1 locus consists of 4 genes (lic1A to lic1D) in a single transcriptional unit that directs phase variable expression of phosphocholine. The lic1A gene is phased off in the RM153 isolate of strain Eagan. LPS from the double mutant, lic1/lic2 had a similar structure to that of lic1 mutant except that there was no chain extension from the central heptose in the inner core (HepII). The lic2 locus consists of 4 genes (lic2A to lic2D). Our structural data were consistent with the proposed function of lic2C, providing the first definitive evidence for its role as the glycosyltransferase required for chain initiation from HepII. The presence of an O-acetyl group at O-3 of the distal heptose (HepIII) was elucidated by 1H NMR on the mild acid liberated core OS samples.

scholarly journals Haemophilus influenzae Pyomyositis in a Patient with Diabetic Ketoacidosis: A Unique Case and Review of Literature

2017 ◽  
Vol 2017 ◽  
pp. 1-3 ◽  
Author(s):  
Kamolyut Lapumnuaypol ◽  
Sanna Fatima ◽  
Pradhum Ram ◽  
Gemlyn George ◽  
Antoinette Climaco
Keyword(s):  
Haemophilus Influenzae ◽  
Respiratory Tract Infections ◽  
Upper Respiratory Tract Infections ◽  
Soft Tissue Infections ◽  
Upper Respiratory Tract ◽  
Review Of Literature ◽  
Unique Case ◽  
Negative Bacillus ◽  
Upper Respiratory ◽  
Tract Infections

Haemophilus influenzae is a Gram-negative bacillus commonly known to cause upper respiratory tract infections. Skin and soft tissue infections are very uncommon. Of these, the majority were associated with necrotizing fasciitis requiring emergent debridement. We report a case of pyomyositis caused by Haemophilus influenzae in an adult with diabetes.

scholarly journals Activities of BMS 284756 (T-3811) against Haemophilus influenzae, Moraxella catarrhalis, andStreptococcus pneumoniae Isolates from SENTRY Antimicrobial Surveillance Program Medical Centers in Latin America (1999)

2001 ◽  
Vol 45 (5) ◽  
pp. 1463-1466 ◽  
Author(s):  
Ana Gales ◽  
Helio Sader ◽  
Ronald N. Jones
Keyword(s):  
Latin America ◽  
Haemophilus Influenzae ◽  
Moraxella Catarrhalis ◽  
Respiratory Tract Infections ◽  
Rank Order ◽  
Therapeutic Option ◽  
Surveillance Program ◽  
Medical Centers ◽  
Antimicrobial Surveillance ◽  
Tract Infections

ABSTRACT The antimicrobial activity of BMS 284756, a novel des-F(6)-quinolone, was comparatively evaluated against 257Streptococcus pneumoniae, 198 Haemophilus influenzae, and 88 Moraxella catarrhalis strains isolated in Latin America between July and September of 1999 as part of the SENTRY Antimicrobial Surveillance Program. Nearly 28.0% ofS. pneumoniae strains were nonsusceptible to penicillin. The rank order of quinolone potency versus S. pneumoniaewas BMS 284756 (MIC at which 90% of isolates were inhibited [MIC90], 0.12 μg/ml) > trovafloxacin (MIC90, 0.25 μg/ml) > gatifloxacin (MIC90, 0.5 μg/ml) > levofloxacin and ciprofloxacin (MIC90, 1 to 2 μg/ml). All S. pneumoniaestrains that were not susceptible to other quinolones were inhibited by BMS 284756 at ≤2 μg/ml. The overall prevalence of β-lactamase production was 15.2% in H. influenzae and 98.9% inM. catarrhalis. BMS 284756 showed excellent potency and spectrum against this group of pathogens, inhibiting all isolates at ≤0.12 μg/ml. BMS 284756 exhibited activity similar to those displayed by the new fluoroquinolones, such as levofloxacin, trovafloxacin, or gatifloxacin, and could be a therapeutic option for empirical treatment of community-acquired respiratory tract infections.

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