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Moonlighting of Helicobacter pylori catalase protects against complement-mediated killing by utilising the host molecule vitronectin.

Richter C, Mukherjee O, Ermert D, Singh B, Su YC, Agarwal V, Blom AM, Riesbeck K - Sci Rep (2016)

Bottom Line: Surprisingly, by using proteomics, we found that the hydrogen peroxide-neutralizing enzyme catalase KatA is a major Vn-binding protein.Deletion of the katA gene in three different strains resulted in impaired binding of Vn.Taken together, the virulence factor KatA is a Vn-binding protein that moonlights on the surface of H. pylori to promote bacterial evasion of host innate immunity.

View Article: PubMed Central - PubMed

Affiliation: Clinical Microbiology, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden.

ABSTRACT
Helicobacter pylori is an important human pathogen and a common cause of peptic ulcers and gastric cancer. Despite H. pylori provoking strong innate and adaptive immune responses, the bacterium is able to successfully establish long-term infections. Vitronectin (Vn), a component of both the extracellular matrix and plasma, is involved in many physiological processes, including regulation of the complement system. The aim of this study was to define a receptor in H. pylori that binds Vn and determine the significance of the interaction for virulence. Surprisingly, by using proteomics, we found that the hydrogen peroxide-neutralizing enzyme catalase KatA is a major Vn-binding protein. Deletion of the katA gene in three different strains resulted in impaired binding of Vn. Recombinant KatA was generated and shown to bind with high affinity to a region between heparin-binding domain 2 and 3 of Vn that differs from previously characterised bacterial binding sites on the molecule. In terms of function, KatA protected H. pylori from complement-mediated killing in a Vn-dependent manner. Taken together, the virulence factor KatA is a Vn-binding protein that moonlights on the surface of H. pylori to promote bacterial evasion of host innate immunity.

No MeSH data available.


Related in: MedlinePlus

H. pylori D katA strains are impaired in Vn-binding.Wt and ΔkatA mutants of H. pylori strains CCUG18943, KR697, and KR497 were incubated with 3 μg of serum Vn. The percentage of Vn-binding was measured by flow-cytometry using FITC-labeled anti-Vn Ab. Statistical significance was determined using Students t-Test, where (*) equals p ≤ 0.05 and (**) equals p ≤ 0.01. Data presented are the mean and SD of three independent experiments performed in technical duplicate.
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f2: H. pylori D katA strains are impaired in Vn-binding.Wt and ΔkatA mutants of H. pylori strains CCUG18943, KR697, and KR497 were incubated with 3 μg of serum Vn. The percentage of Vn-binding was measured by flow-cytometry using FITC-labeled anti-Vn Ab. Statistical significance was determined using Students t-Test, where (*) equals p ≤ 0.05 and (**) equals p ≤ 0.01. Data presented are the mean and SD of three independent experiments performed in technical duplicate.

Mentions: H. pylori KatA, like other catalases, is a predicted cytoplasmic protein with no signal-sequence for any known transport pathway. However, presence of KatA in the periplasm and even surface location has been proposed1819, even though the means of translocation remain elusive. Obviously, surface location of KatA would be essential for the interaction with Vn. Thus, we wanted to verify the KatA-dependent Vn binding with intact bacteria and constructed katA deletion mutants in H. pylori strains CCUG18943 and KR697, as well as in the weak Vn-binding KR497. All H. pylori ΔkatA strains showed significantly less binding to Vn when compared to the wild type (wt) counterparts in flow cytometry (Fig. 2). Deletion of katA resulted in 21% reduction in binding of Vn to H. pylori CCUG18943, whereas a 50% reduction in Vn binding was observed with the two strains KR697ΔkatA and KR497 ΔkatA when compared to their respective wt (Fig. 2). Taken together, our data provided additional evidence for surface localisation of KatA and furthermore showed that KatA is relevant for Vn binding to whole bacteria.


Moonlighting of Helicobacter pylori catalase protects against complement-mediated killing by utilising the host molecule vitronectin.

Richter C, Mukherjee O, Ermert D, Singh B, Su YC, Agarwal V, Blom AM, Riesbeck K - Sci Rep (2016)

H. pylori D katA strains are impaired in Vn-binding.Wt and ΔkatA mutants of H. pylori strains CCUG18943, KR697, and KR497 were incubated with 3 μg of serum Vn. The percentage of Vn-binding was measured by flow-cytometry using FITC-labeled anti-Vn Ab. Statistical significance was determined using Students t-Test, where (*) equals p ≤ 0.05 and (**) equals p ≤ 0.01. Data presented are the mean and SD of three independent experiments performed in technical duplicate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834553&req=5

f2: H. pylori D katA strains are impaired in Vn-binding.Wt and ΔkatA mutants of H. pylori strains CCUG18943, KR697, and KR497 were incubated with 3 μg of serum Vn. The percentage of Vn-binding was measured by flow-cytometry using FITC-labeled anti-Vn Ab. Statistical significance was determined using Students t-Test, where (*) equals p ≤ 0.05 and (**) equals p ≤ 0.01. Data presented are the mean and SD of three independent experiments performed in technical duplicate.
Mentions: H. pylori KatA, like other catalases, is a predicted cytoplasmic protein with no signal-sequence for any known transport pathway. However, presence of KatA in the periplasm and even surface location has been proposed1819, even though the means of translocation remain elusive. Obviously, surface location of KatA would be essential for the interaction with Vn. Thus, we wanted to verify the KatA-dependent Vn binding with intact bacteria and constructed katA deletion mutants in H. pylori strains CCUG18943 and KR697, as well as in the weak Vn-binding KR497. All H. pylori ΔkatA strains showed significantly less binding to Vn when compared to the wild type (wt) counterparts in flow cytometry (Fig. 2). Deletion of katA resulted in 21% reduction in binding of Vn to H. pylori CCUG18943, whereas a 50% reduction in Vn binding was observed with the two strains KR697ΔkatA and KR497 ΔkatA when compared to their respective wt (Fig. 2). Taken together, our data provided additional evidence for surface localisation of KatA and furthermore showed that KatA is relevant for Vn binding to whole bacteria.

Bottom Line: Surprisingly, by using proteomics, we found that the hydrogen peroxide-neutralizing enzyme catalase KatA is a major Vn-binding protein.Deletion of the katA gene in three different strains resulted in impaired binding of Vn.Taken together, the virulence factor KatA is a Vn-binding protein that moonlights on the surface of H. pylori to promote bacterial evasion of host innate immunity.

View Article: PubMed Central - PubMed

Affiliation: Clinical Microbiology, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden.

ABSTRACT
Helicobacter pylori is an important human pathogen and a common cause of peptic ulcers and gastric cancer. Despite H. pylori provoking strong innate and adaptive immune responses, the bacterium is able to successfully establish long-term infections. Vitronectin (Vn), a component of both the extracellular matrix and plasma, is involved in many physiological processes, including regulation of the complement system. The aim of this study was to define a receptor in H. pylori that binds Vn and determine the significance of the interaction for virulence. Surprisingly, by using proteomics, we found that the hydrogen peroxide-neutralizing enzyme catalase KatA is a major Vn-binding protein. Deletion of the katA gene in three different strains resulted in impaired binding of Vn. Recombinant KatA was generated and shown to bind with high affinity to a region between heparin-binding domain 2 and 3 of Vn that differs from previously characterised bacterial binding sites on the molecule. In terms of function, KatA protected H. pylori from complement-mediated killing in a Vn-dependent manner. Taken together, the virulence factor KatA is a Vn-binding protein that moonlights on the surface of H. pylori to promote bacterial evasion of host innate immunity.

No MeSH data available.


Related in: MedlinePlus