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Woo-Kon Lee

Publications and source records attributed to Woo-Kon Lee.

10 recordsLinked to original sources
PubMed2006

Quantitative effect of luxS gene inactivation on the fitness of Helicobacter pylori.

Furanone metabolites called AI-2 (autoinducer 2), used by some bacterial species for signaling and cell density-regulated changes in gene expression, are made while regenerating S-adenosyl methionine (SAM) after its use as a methyl donor. The luxS-encoded enzyme, in particular, participates in this activated methyl cycle by generating both a pentanedione, which is transformed chemically into these AI-2 compounds, and homocysteine, a precursor of methionine and SAM. Helicobacter pylori seems to contain the genes for this activated methyl cycle, including luxS, but not genes for AI-2 uptake and transcriptional regulation. Here we report that deletion of luxS in H. pylori reference strain SS1 diminished its competitive ability in mice and motility in soft agar, whereas no such effect was seen with an equivalent Delta luxS derivative of the unrelated strain X47. These different outcomes are consistent with H. pylori's considerable genetic diversity and are reminiscent of phenotypes seen after deletion of another nonessential metabolic gene, that encoding polyphosphate kinase 1. We suggest that synthesis of AI-2 by H. pylori may be an inadvertent consequence of metabolite flux in its activated methyl cycle and that impairment of this cycle and/or pathways affected by it, rather than loss of quorum sensing, is deleterious for some H. pylori strains. Also tenable is a model in which AI-2 affects other microbes in H. pylori's gastric ecosystem and thereby modulates the gastric environment in ways to which certain H. pylori strains are particularly sensitive.

Animals↗
PubMed2006

Helicobacter pylori adhesion to carbohydrates.

Adherence of bacterial pathogens to host tissues contributes to colonization and virulence and typically involves specific interactions between bacterial proteins called adhesins and cognate oligosaccharide (glycan) or protein motifs in the host that are used as receptors. A given pathogen may have multiple adhesins, each specific for a different set of receptors and, potentially, with different roles in infection and disease. This chapter provides strategies for identifying and analyzing host glycan receptors and the bacterial adhesins that exploit them as receptors, with particular reference to adherence of the gastric pathogen Helicobacter pylori.

Bacterial Adhesion↗
PubMed2006

Quantitative analysis of representative proteome components and clustering of Helicobacter pylori clinical strains.

BACKGROUND: Several Helicobacter pylori proteins have been reported to be associated with severe symptoms of gastric disease. However, expression levels of most of these disease-associated proteins require further evaluation in order to clarify their relationships with gastric disease patterns. Representative proteome components of 71 clinical isolates of H. pylori were analyzed quantitatively to determine whether the protein expression levels were associated with gastric diseases and to cluster clinical isolates. METHODS: After two-dimensional electrophoresis (2-DE) of H. pylori isolates, spot intensities were analyzed using pdquest 2-D Gel Analysis Software. The intensities of 10 representative protein spots, identified by peptide fingerprinting using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) or peptide sequencing using quadrupole TOF MS, were subjected to the nonparametric Mann-Whitney test and hierarchical agglomerative cluster analysis. The relationship between clusters and gastric diseases was analyzed by the chi-squared test. RESULTS: Although the spot intensities of the 10 representative proteins were highly variable within each gastric disease group, the expression levels of CagA, UreB, GroEL, EF-Tu, EF-P, TagD, and FldA showed some significant differences among the gastric disease patterns. On the basis of the 10 target protein intensities, hierarchical agglomerative cluster analysis generated a dendrogram with clusters indicative of chronic gastritis/gastric cancers and gastric/duodenal ulcers. CONCLUSION: These results indicated that quantitative analysis of proteome components is a feasible method for examining disease-associated proteins and clustering clinical strains of H. pylori.

Adult↗
PubMed2004

Proteomic analysis of the sarcosine-insoluble outer membrane fraction of Helicobacter pylori strain 26695.

Helicobacter pylori causes gastroduodenal disease, which is mediated in part by its outer membrane proteins (OMPs). To identify OMPs of H. pylori strain 26695, we performed a proteomic analysis. A sarcosine-insoluble outer membrane fraction was resolved by two-dimensional electrophoresis with immobilized pH gradient strips. Most of the protein spots, with molecular masses of 10 to 100 kDa, were visible on the gel in the alkaline pI regions (6.0 to 10.0). The proteome of the OMPs was analyzed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Of the 80 protein spots processed, 62 spots were identified; they represented 35 genes, including 16 kinds of OMP. Moreover, we identified 9 immunoreactive proteins by immunoblot analysis. This study contributes to the characterization of the H. pylori strain 26695 proteome and may help to further elucidate the biological function of H. pylori OMPs and the pathogenesis of H. pylori infection.

Bacterial Outer Membrane Proteins↗
PubMed2004

Alanine-threonine polymorphism of Helicobacter pylori RpoB is correlated with differential induction of interleukin-8 in MKN45 cells.

Geographical differences in the genetic diversity of Helicobacter pylori isolates were examined by analyzing rpoB sequences. An extremely high level of allelic diversity among H. pylori strains was found. The rpoB sequences of Asian and non-Asian (North and South American, European, and South African) strains were found to differ. An amino acid polymorphism (alanine and threonine RpoB types) was found at the 497th residue by deduced amino acid analysis. RpoB with a threonine residue (RpoB(Thr)) was uniquely present in East Asian countries, and two-thirds of the H. pylori isolate population in this region was RpoB(Thr); however, this type was rare or absent in Western countries, where RpoB(Ala) predominated. RpoB(Thr) strains induced a much larger amount of interleukin-8, a chemokine that plays an important role in chronic inflammation, than RpoB(Ala) strains in cultured MKN45 cells.

Alanine↗
PubMed2003

Characterization of a small cryptic plasmid, pHP51, from a Korean isolate of strain 51 of Helicobacter pylori.

The nucleotide sequence of a 3955-bp Helicobacter pylori plasmid, pHP51 was determined, and two open reading frames, ORF1 and ORF2, were identified. The deduced amino acid sequence of ORF1 was highly conserved (87-89%) among plasmid replication initiation proteins, RepBs. The function of ORF2 was not assigned because it lacked known functional domains or sequence similarity with other known proteins, although it had a HPFXXGNG motif that was also found in the cAMP-induced filamentation (fic) gene. Three kinds of repeats were present on the plasmid outside of the ORFs, including the R1 and R2 repeats that are common in H. pylori plasmids. One 100-bp sequence detected in the noncoding region of pHP51 was highly similar to the genomic sequence of H. pylori 26695.

Amino Acid Sequence↗
PubMed2003

pHP489, a Helicobacter pylori small cryptic plasmid, harbors a novel gene coding for a replication initiation protein.

We have analyzed a Helicobacter pylori plasmid, pHP489. The 1222-bp nucleotide sequence had one open reading frame, a DnaA-binding site, one direct repeat, and three inverted repeats. The (G+C) content of pHP489 was 33.3%. Although the nucleic acid sequence and deduced amino acid sequence were homologous to those of other bacterial plasmid Rep proteins, the degree of similarity was very low. A deletion analysis showed that the Rep protein was not required for the replication of pHP489 in its H. pylori host, but the host replication machinery was needed.

Amino Acid Sequence↗
PubMed2003

Detection of Helicobacter pylori in gastric mucosa of patients with gastroduodenal diseases by PCR-restriction analysis using the RNA polymerase gene (rpoB).

A novel PCR restriction analysis method using the RNA polymerase beta-subunit- coding gene (rpoB) was employed to both detect and identify Helicobacter pylori in biopsy specimens and culture isolates. The rpoB DNAs (458 bp) were specifically amplified by PCR with the Helicobacter-specific primers (HF and HR). Based on the determined rpoB sequences of the culture isolates, an H. pylori-specific restriction site, Tru9I, was found. H. pylori can be identified by observing two discernible DNA fragments (288 and 138 bp) after Tru9I digestion and agarose gel electrophoresis. The rpoB PCR and subsequent restriction analysis (PRA) enabled the specific detection and identification of H. pylori in biopsy specimens from patients with gastroduodenal diseases. The rpoB PRA conferred a compatible or a slightly higher positive rate (53.7%) than did the Campylobacter-like organism (CLO) test (50.4%) and glmM PCR (48.8%), suggesting that it is useful for diagnosing an H. pylori infection without culture in the clinical laboratory.

Bacterial Typing Techniques↗
PubMed2002

Identifying the major proteome components of Helicobacter pylori strain 26695.

The whole genome sequences of Helicobacter pylori strain 26695 have been reported. Whole cell proteins of H. pylori strain 26695 cells were obtained and analyzed by two-dimensional electrophoresis, using immobilized pH gradient strips. The most abundant proteins were shown in the region of pI 4.0-9.5 with molecular masses from 10 to 100 kDa. Soluble proteins were precipitated by the use of 0-80% saturated solutions of ammonium sulfate. Soluble proteins precipitated by the 0-40% saturations of ammonium sulfate produced similar spot profiles and their abundant protein spots had acidic pI regions. However, a number of soluble proteins precipitated by more than 60% saturation of ammonium sulfate were placed in the alkaline pI regions, compared to those precipitated by 40% saturation. In addition, we have performed an extensive proteome analysis of the strain utilizing peptide MALDI-TOF-MS. Among the 345 protein spots processed, 175 proteins were identified. The identified spots represented 137 genes. One-hundred and fifteen proteins were newly identified in this study, including DNA polymerase III beta-subunit. These results might provide guidance for the enrichment of H. pylori proteins and contribute to construct a master protein map of H. pylori.

Bacterial Proteins↗