The Helicobacter pylori Ferric Uptake Regulator (Fur) Is Essential for Growth Under Sodium Chloride Stress

Hanan Gancz,D. Scott Merrell 한국미생물학회 2011 The journal of microbiology Vol.49 No.2

Epidemiological data and animal models indicate that Helicobacter pylori and dietary NaCl have a synergistic ill effect on gastric maladies. Here we show that the Ferric Uptake Regulator (Fur), which is a crucial regulatory factor required for H. pylori colonization, is essential for growth in the presence of high NaCl concentrations. Moreover, we demonstrate that the transcriptional response induced by sodium chloride stress exhibits similarities to that seen under iron depletion.

Geographic diversity in Helicobacter pylori oipA genotype between Korean and United States isolates

Kim Aeryun,Lai Jing,Merrell D. Scott,Kim Ji-Hye,Su Hanfu,Cha Jeong-Heon 한국미생물학회 2021 The journal of microbiology Vol.59 No.12

Helicobacter pylori outer membrane inflammatory protein A (OipA) was originally named for its role in inducing inflammation in the host, as evidenced by high mucosal IL-8 levels. Expression of OipA is regulated by phase variation of a CT dinucleotide-repeat located in the 5 region of the gene. However, little is known about OipA geographic diversity across isolates. To address this gap, we conducted a large-scale molecular epidemiologic analysis using H. pylori clinical isolates obtained from two geographically distinct populations: Korea and the United States (US). Most Korean isolates (98.7%) possessed two copies of oipA located at two specific loci (A and B) while all US isolates contained only one copy of oipA at locus A. Furthermore, most Korean oipA (94.8%) possessed three or less CT repeats while most US oipA (96.6%) contained five or more CT repeats. Among the two copies, all Korean H. pylori possessed at least one oipA ‘on’ phase variant while the single copy of oipA in US isolates showed 56.2% ‘on’ and 43.8% ‘off.’ Thus, host differences seem to have driven geographic diversification of H. pylori across these populations such that OipA expression in US isolates is still regulated by phase variation with 5 or more CT repeats, while Korean isolates always express OipA; duplication of the oipA combined with a reduction of CT repeats to three or less ensures continued expression. En masse, these findings suggest that diversity in the oipA gene copy number, CT repeats, and phase variation among H. pylori from different populations may confer a benefit in adaptation to particular host populations.

Nontraditional Therapies to Treat Helicobacter pylori Infection

Morris O. Makobongo,D. Scott Merrell,Jeremy J. Gilbreath 한국미생물학회 2014 The journal of microbiology Vol.52 No.4

The Gram-negative pathogen Helicobacter pylori is increasinglymore resistant to the three major antibiotics (metronidazole,clarithromycin and amoxicillin) that are most commonlyused to treat infection. As a result, there is an increasedrate of treatment failure; this translates into an overall highercost of treatment due to the need for increased length of treatmentand/or the requirement for combination or sequentialtherapy. Given the rise in antibiotic resistance, the complicatedtreatment regime, and issues related to patient compliancethat stem from the duration and complexity of treatment,there is clearly a pressing need for the development ofnovel therapeutic strategies to combat H. pylori infection. As such, researchers are actively investigating the utility ofantimicrobial peptides, small molecule inhibitors and naturopathictherapies. Herein we review and discuss each ofthese novel approaches as a means to target this importantgastric pathogen.

Frequency of Antibiotic Resistance in Helicobacter pylori Strains Isolated from the Northern Population of Iran

Amin Talebi Bezmin Abadi,D. Scott Merrell,Tarang Taghvaei,Ashraf Mohabbati Mobarez,Beth M. Carpenter 한국미생물학회 2011 The journal of microbiology Vol.49 No.6

The purpose of this study was to evaluate the primary resistance rates of recent clinical Helicobacter pylori isolates to the most commonly used antibiotics in Iran. Two hundreds and ten patients presenting with gastric maladies between January and July of 2009 were enrolled in this study. Endoscopy was performed, and biopsy specimens were collected from each patient for subsequent bacterial culture of H. pylori. Single colony isolates from each patient were then used for antimicrobial susceptibility testing. The disk diffusion method was used to determine susceptibility patterns. One hundred and ninety-seven of the patients were H. pylori positive (93.8%). The rates of resistance to tetracycline, amoxicillin, ciprofloxacin, metronidazole, clarithromycin, and furizoladone were 37.1%, 23.9%, 34.5%, 65.5%, 45.2%, and 61.4%, respectively. A significant association between amoxicillin resistance and disease state (P<0.05) was identified. Furthermore, some double, triple, quadruple, and quintuple combinations of antibiotic resistance were found to be associated with disease state. This study evaluated the prevalence of H. pylori resistance to the most commonly prescribed antibiotics used in Iran and showed that resistance rates were generally higher than previously reported. This data adds to the growing body of evidence that suggests there is increasing antibiotic resistance among H. pylori isolates, which likely is responsible for the decreasing efficacy of anti-H. pylori therapy at the local and global level. Hence, there is a need for continued monitoring of resistance patterns, especially at the local level, and for incorporation of that information into treatment regimens for H. pylori infections.

Complementation System for Helicobacter pylori

김진문,Sung-Whan Kim,Sungil Jang,D. Scott Merrell,차정헌 한국미생물학회 2011 The journal of microbiology Vol.49 No.3

Previously Langford et al. (2006) developed the pIR203C04 complementation system for Helicobacter pylori,which can be used to complement and restore phenotypic effects in H. pylori mutant, and furthermore they used the complementation system in vivo experiments to animals without altering the ability of strain SS1 to colonize mice. In their previous study, the pIR203C04 was able to transform 26695, SS1, J99, and 43504 H. pylori strains by an electroporation method. However, in the present study using a natural transformation the pIR203C04 transformed only 26695 H. pylori but not SS1, J99, 7.13, and G27 H. pylori strains. Since the useful complementation system has a limitation of narrow selection among H. pylori strains, we redesigned the complementation system for the improvement. The same intergenic chromosomal site between hp0203 and hp0204 was utilized for the new complementation system because the insertion at the intergenic site didn’t show any polar effects and disruption of other H. pylori genes. The genome sequence analysis showed that the intergenic regions among H. pylori strains may have too low homology to each others to do a homologous recombination. Thus, in addition to the short intergenic region, the fragments of the new complementation system included 3′ conserved parts of hp0203 and hp0204 coding regions. Between the fragments there are a chloramphenicol acetyltransferase cassette and multicloning sites, resulting in pKJMSH. DNA fragment of the interest can be cloned into the multicloning sites of pKJMSH and the fragment can be integrated at the intergenic region of H. pylori chromosome by the homologous recombination. Indeed, by the natural transformation, pKJMSH was able to transform all five H. pylori strains of 26695,SS1, J99, 7.13, and G27, which are common for the investigation of molecular pathogenesis. Thus, the new pKJMSH complementation system is applicable to most H. pylori wild-type stains.

Helicobacter pylori apo-Fur Regulation Appears Unconserved Across Species

Shana Miles,Beth M. Carpenter,Hanan Gancz,D. Scott Merrell 한국미생물학회 2010 The journal of microbiology Vol.48 No.3

The Ferric Uptake Regulator (Fur) is a transcriptional regulator that is conserved across a broad number of bacterial species and has been shown to regulate expression of iron uptake and storage genes. Additionally, Fur has been shown to be an important colonization factor of the gastric pathogen Helicobacter pylori. In H. pylori, Fur-dependent regulation appears to be unique in that Fur is able to act as a transcriptional repressor when bound to iron as well as in its iron free (apo) form. To date, apo-regulation has not been identified in any other bacterium. To determine whether Fur from other species has the capacity for aporegulation, we investigated the ability of Fur from Escherichia coli, Campylobacter jejuni, Desulfovibrio vulgaris Hildenborough, Pseudomonas aeruginosa, and Vibrio cholerae to complement both iron-bound and apo-Fur regulation within the context of a H. pylori fur mutant. We found that while some Fur species (E. coli, C. jejuni, and V. cholerae) complemented iron-bound regulation, apo-regulation was unable to be complemented by any of the examined species. These data suggest that despite the conservation among bacterial Fur proteins, H. pylori Fur contains unique structure/function features that make it novel in comparison to Fur from other species.

Characterization of East-Asian Helicobacter pylori encoding Western EPIYA-ABC CagA

Tissera Kavinda,Kim Myeong-A,Lai Jing,Angulmaduwa Sacheera,Kim Aeryun,Merrell D. Scott,김지혜,Su Hanfu,Cha Jeong-Heon 한국미생물학회 2022 The journal of microbiology Vol.60 No.2

The polymorphic bacterial oncoprotein, CagA shows geography- dependent variation in the C-terminal Glu-Pro-Ile- Tyr-Ala (EPIYA) motifs; East-Asian H. pylori isolates carry the ABD type while Western isolates carry the ABC type. In Western isolates, the EPIYA-C motif is sometimes found in multi-copy and this genotype is associated with disease severity. Interestingly, a small number of East-Asian H. pylori isolates have been found to carry Western ABC-type CagA. To gain a better understanding of these unusual isolates, the genomes of four Korean H. pylori clinical isolates carrying ABC-type CagA were sequenced via third generation (Pac- Bio SMRT) sequencing technology. The obtained data were utilized for phylogenetic analysis as well as comparison of additional virulence factors that are known to show geographic- dependent polymorphisms. Three of four isolates indeed belonged to the hpEastAsia group and showed typical East- Asian polymorphism in virulence factors such as homA/B/C, babA/B/C, and oipA. One isolate grouped to HpAfrica and showed typical Western polymorphism of virulence factors such as cagA, homA/B/C, and oipA. To understand the occurrence of the multi-copy EPIYA-C motif genotype in an East- Asian H. pylori background, the Korean clinical isolate, K154 was analyzed; this strain belonged to hpEastAsia but encoded CagA EPIYA-ABCCCC. Based on DNA sequence homology within the CagA multimerization (CM) sequence that flanked the EPIYA-C motifs, we predicted that the number of C motifs might change via homologous recombination. To test this hypothesis, K154 was cultured for one generation and 287 single colonies were analyzed for the number of EPIYA-C motifs using PCR-based screening and DNA sequencing verification. Three out of 284 (1%) single colony isolates showed changes in the number of EPIYA-C motifs in vitro; one isolate increased to five EPIYA-C motifs, one decreased to three EPIYA-C motifs, and one completely deleted the EPIYA-C motifs. The capacity for dynamic changes in the number of EPIYA-C repeats of CagA may play a role in generating important intraspecies diversity in East-Asian H. pylori.

Genetic analysis of Helicobacter pylori clinical isolates suggests resistance to metronidazole can occur without the loss of functional rdxA

Kim, So Yeong,Joo, Young Min,Lee, Hak Sung,Chung, In-Sik,Yoo, Yun-Jung,Merrell, D Scott,Cha, Jeong-Heon Springer Science and Business Media LLC 2009 The Journal of Antibiotics Vol.62 No.1

<P>Resistance to metronidazole (MTZ) in Helicobacter pylori is associated with mutations in rdxA, encoding an oxygen-insensitive NADPH nitroreductase, and mutations in frxA, encoding a NAD(P)H-flavin oxidoreductase. Despite this association, the strict correlation of MTZ resistance with mutations in rdxA or frxA is still controversial. In this study, rdxA allelic replacement was used to distinguish resistance-associated nucleotide mutations from the natural genetic diversity of H. pylori. Replacement with truncated rdxA resulted in MTZ resistance, whereas replacement with missense-mutated rdxA from resistant clinical isolates failed to yield MTZ resistance. Thus, although truncation of rdxA confers MTZ resistance in G27 H. pylori, MTZ resistance found in other clinical isolates is not due to the identified amino-acid substitutions. Three of our MTZ-resistant clinical isolates expressed functional rdxA and two of these also encoded full-length frxA. Therefore, MTZ resistance can arise in H. pylori possessing functional rdxA, suggesting that other factors are involved in MTZ resistance.</P>

Helicobacter pylori outer membrane protein, HomC, shows geographic dependent polymorphism that is influenced by the Bab family

Aeryun Kim,Stephanie L. Servetas,Jieun Kang,Jinmoon Kim,장성일,Yun Hui Choi,Hanfu Su,Yeong-Eui Jeon,Youngmin A. Hong,유윤정,D. Scott Merrell,차정헌 한국미생물학회 2016 The journal of microbiology Vol.54 No.12

The array of outer membrane proteins (OMPs) found in Helicobacter pylori provides a crucial component for persistent colonization within the gastric niche. Not only does H. pylori harbor a wide number of OMPs, but these OMPs often vary across strains; this likely contributes to immune evasion, adaptation during long term colonization, and potentially differential disease progression. Previous work from our group described OMP differences among the Bab family (babA, babB, and babC) and Hom family (homA and homB) from 80 American H. pylori clinical isolates (AH) and 80 South Korean H. pylori clinical isolates (KH). In the current study, we expanded our investigation to include the less well characterized Hom family member, HomC. Overall, we identified and genotyped three homC variants: homCS, homCL, and homCM, in both populations. Similar to other polymorphic genes, the KH group showed less overall diversity, with 97.5% of strains harboring homCL. In contrast, a more heterogeneous profile was observed in strains derived from an American population; we found nearly equal distribution of homCS and homCL. Further analysis of the AH group identified associations between homC polymorphism and bab genotype; in AH strains, there was a significant association between homCL and carriage of babA at locus A. Since babA is an important virulence factor for the development of severe gastric disease, these data may suggest that homC polymorphism plays a role in H. pylori pathogenesis.