Essential role of Helicobacter pylori apolipoprotein N-acyltransferase (Lnt) in stomach colonization
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE241938 | GEO | 2023/10/17
REPOSITORIES: GEO
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Project description:Essential role of Helicobacter pylori apolipoprotein N-acyltransferase (Lnt) in stomach colonization
| PRJNA1010783 | ENA
Project description:Bacterial lipoproteins are post-translationally modified with acyl chains, anchoring these proteins to bacterial membranes. In Gram-negative bacteria, three enzymes complete the modifications. Lgt (which adds two acyl chains) and LspA (which removes the signal peptide) are essential. Lnt (which adds a third acyl chain) is not essential in certain bacteria including Francisella tularensis, Neisseria gonorrhoeae, and Acinetobacter baumannii. Deleting lnt results in mild to severe physiologic changes. We previously showed lnt is not essential for Helicobacter pylori growth in vitro. Here, the physiologic consequences of deleting lnt in H. pylori and the role of Lnt in the host response to H. pylori were examined using in vitro and in vivo models. Comparing wild-type, Δlnt, and complemented mutant H. pylori, no changes in growth rates or sensitivity to acid or antibiotics were observed. Since deleting lnt changes the number of acyl chains on lipoproteins and the number of acyl chains on lipoproteins impacts the innate immune response through Toll-like receptor 2 (TLR2) signaling, primary human gastric epithelial cells were treated with a purified lipoprotein from wild-type or lnt mutant H. pylori. Differential gene expression analysis indicated that lipoprotein from the lnt mutant induced a more robust TLR2 response. In a complementary approach, we infected wild-type and Tlr2-/- mice and found that both the wild-type and complemented mutant strains successfully colonized the animals. However, the lnt mutant strain was unable to colonize either mouse strain. These results show that lnt is essential for H. pylori colonization and identifies lipoprotein synthesis as a target for therapeutic intervention.
| S-EPMC10715074 | biostudies-literature
Project description:Helicobacter pylori is a highly successful and important human pathogen that causes chronic gastritis, peptic ulcer diseases and gastric cancer. Innate immunity plays an important role of the primary defense against pathogens and epidemiological studies have suggested a role of toll-like receptor 1 (TLR1) in the risk of H. pylori acquisition. We performed microarray analysis of gastric mucosal biopsy specimens from H. pylori-positive and uninfected subjects; infection was associated with an ~15-fold up-regulation of TLR10 (p <0.001). Quantitative RT-PCR confirmed TLR10 mRNA levels were increased 3-fold in H. pylori-infection (p <0.001) and immunohistochemistory using anti-TLR10 polyclonal antibodies showed increased TLR10 expression in gastric epithelial cells of infected individuals. In vitro experiments where H. pylori was co-cultured with NCI-N87 gastric cells showed significant H. pylori-specific up-regulation of TLR10 mRNA levels and a correlation with TLR2 mRNA levels (R = 0.87, P <0.001). We compared combinations of TLRs for their ability to mediate NF-_B activation. NF-_B activation was increased following exposure to heat killed H. pylori or H. pylori-LPS only with the TLR2/TLR10 heterodimer. These findings suggest TLR10 is a functional receptor involved in the innate immune response to H. pylori infection and that TLR2/TLR10 heterodimer possibly functions in the recognition of H. pylori-LPS.
2015-06-01 | GSE60427 | GEO
Project description:Numerous proteins synthesized in cells ranging from bacteria to humans have to be posttranslationally acylated to become biologically active. Bacterial Repeats in ToXin (RTX) cytolysins form a prominent group of proteins that are synthesized as inactive protoxins and undergo a posttranslational acylation on ε-amino groups of two internal conserved lysine residues by co-expressed toxin-activating acyltransferases. We investigated how the chemical nature, position and number of bound acyl chains govern the activities of Bordetella pertussis adenylate cyclase toxin (CyaA), Escherichia coli α-hemolysin (HlyA) and Kingella kingae cytotoxin (RtxA). The three protoxins were acylated in the same E. coli cell background by either of the CyaC, HlyC and RtxC acyltransferases. The results revealed that the acyltransferase itself selects from the acyl-ACP pool of the producing bacterium the type of the acyl chain of adapted length to be covalently linked to the protoxin. The acyltransferase also selects whether both or only one of two conserved lysine residues of the protoxin will be posttranslationally acylated. Functional assays then revealed that RtxA has to be modified by 14-carbon fatty acyl chains to be biologically active, while HlyA remains active also when modified by 16-carbon acyl chains and CyaA is activated exclusively by 16-carbon acyl chains. These results suggest a structural adaptation of the toxin molecules to the length of the acyl chains used for modification of their crucial acylated lysine residue in the second, more conserved acylation site
2020-05-20 | PXD018859 | Pride
Project description:De novo fatty acid synthesis produces the acyl units needed to generate phospholipids, lipoproteins, enzyme prosthetic factors, polyketides, and mycolic acids in Mycobacterium tuberculosis (Mtb). Here, we identifed sALT629, a novel butoxyphenyl-tetrazole-acetamide compound that inhibits de novo lipid synthesis in Mtb. This compound disrupts the Mtb lipidome and prevents incorporation of metabolic tracers into acyl chains of Mtb lipids. Unexpectedly, we also found that sALT629 treatment significantly depleted triacylglycerol (TAG) pools as a metabolic compensation mechanism when de novo fatty acid synthesis was inhibited. Resistance to sALT629 was mediated by loss of function mutations in HadC, the non-essential hydroxyacyl-ACP-dehydratase subunit involved in the synthesis of long-chain oxygenated mycolic acids. Inactivating HadC rescued sALT629-mediated inhibition by sustaining TAG pools to fulfill Mtb’s biosynthetic demand for acyl chains. Lastly, loss of function HadC resistance mutations resulted in cell wall perturbations that confer fitness defects in vitro and in vivo suggesting that this specific resistance mechanism is unlikely to arise in Mtb in a clinical setting.
2025-06-02 | GSE298382 | GEO
Project description:This SuperSeries is composed of the following subset Series: GSE25146: Changes in gene expression in AGS cells in response to Helicobacter pylori lipopolysaccharide GSE25147: Changes in gene expression in MKN45 cells in response to Helicobacter pylori lipopolysaccharide GSE25148: Changes in gene expression in HEK-TLR2 cells in response to Helicobacter pylori lipopolysaccharide Refer to individual Series
2011-01-12 | E-GEOD-25155 | biostudies-arrayexpress
Project description:This study set out to identify global changes in gene expression in human embryonic kidney (HEK) cells stably transfected with Toll-like receptor 2 (TLR2) over a 48 hour time-course, following stimulation with 10 μg/ml lipopolysaccharide (LPS) from the gastric pathogen H. pylori. Microarray analysis was used to compare changes in gene expression between cells treated with 10 μg/ml H. pylori LPS and untreated cells at the same time point. Total RNA was harvested from HEK-TLR2 cells following treatment with LPS for 2, 4, 8, 24 and 48h or untreated cells at the same time-point. 2 independent experiments were carried out. RNA was labeled and hybridized to GeneChips to analyse changes in gene expression.
2011-01-12 | E-GEOD-25148 | biostudies-arrayexpress
Project description:This study set out to identify global changes in gene expression in human embryonic kidney (HEK) cells stably transfected with Toll-like receptor 2 (TLR2) over a 48 hour time-course, following stimulation with 10 μg/ml lipopolysaccharide (LPS) from the gastric pathogen H. pylori. Microarray analysis was used to compare changes in gene expression between cells treated with 10 μg/ml H. pylori LPS and untreated cells at the same time point.
2011-01-12 | GSE25148 | GEO
Project description:In zebrafish, maternally deposited yolk is the source of nutrients for embryogenesis prior to digestive system maturation. Yolk nutrients are processed and secreted to the growing organism by an extra-embryonic tissue, the yolk syncytial layer (YSL). Export of lipid from the YSL occurs through the production of triacylglycerol-rich lipoproteins. Here we report that mutations in the triacylglycerol synthesis enzyme, diacylglycerol acyltransferase-2 (Dgat2), cause yolk sac opacity due to aberrant accumulation of cytoplasmic lipid droplets in the YSL. Though triacylglycerol synthesis continues, it is not properly coupled to lipoprotein production as dgat2 mutants produce fewer, smaller, ApoB-containing lipoproteins. Unlike DGAT2-null mice, which are lipopenic and die soon after birth, zebrafish dgat2 mutants are viable, fertile and exhibit normal mass and adiposity. Residual Dgat activity cannot be explained by the activity of other known Dgat isoenzymes, as dgat1a;dgat1b;dgat2 triple mutants continue to produce YSL lipid droplets and remain viable as adults. Further, the newly identified diacylglycerol acyltransferase, Tmem68, is also not responsible for the residual triacylglycerol synthesis activity. Unlike overexpression of Dgat1a and Dgat1b, monoacylglycerol acyltransferase-3 (Mogat3b) overexpression does not rescue yolk opacity, suggesting it does not possess Dgat activity in the YSL. However, mogat3b;dgat2 double mutants exhibit increased yolk opacity and often have structural alterations of the yolk extension. Quadruple mogat3b;dgat1a;dgat1b;dgat2 mutants either have severely reduced viability and stunted growth, or do not survive past 3 days post fertilization, depending on the dgat2 mutant allele present. Our study highlights the remarkable ability of vertebrates to synthesize triacylglycerol through multiple biosynthetic pathways.
2024-11-07 | GSE279170 | GEO
Project description:Helicobacter pylori, the most common etiologic agent of gastric diseases including gastric cancer, is auxotrophic for cholesterol and has to hijack it from gastric epithelia. Upon uptake, the bacteria convert cholesterol to cholesteryl 6'-O-acyl-α-D-glucopyranoside (CAG) to promote lipid raft clustering in the host cell membranes. However, how CAG appears in the host to exert the pathogenesis still remains ambiguous. Herein we identified hp0499 to be the gene of cholesteryl α-D-glucopyranoside acyltransferase (CGAT). Together with cholesteryl glucosyltransferase (catalyzing the prior step), CGAT is secreted via outer membrane vesicles to the host cells for direct synthesis of CAG. This significantly enhances lipid rafts clustering, gathers adhesion molecules (including Lewis antigens and integrins α5, β1), and promotes more bacterial adhesion. Furthermore, the clinically used drug amiodarone was shown as a potent inhibitor of CGAT to effectively reduce the bacterial adhesion, indicating that CGAT is a potential target of therapeutic intervention.
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