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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

Surface exposure of KatA correlates with Vn binding capacity.Eleven H. pylori isolates were tested for their Vn binding capacity and KatA surface density in separate flow cytometric assays. Data shown are the mean of at least three independent experiments. Linear regression was performed for all data points.
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f6: Surface exposure of KatA correlates with Vn binding capacity.Eleven H. pylori isolates were tested for their Vn binding capacity and KatA surface density in separate flow cytometric assays. Data shown are the mean of at least three independent experiments. Linear regression was performed for all data points.

Mentions: Having identified the binding site for Vn within a flexible region, which are often less conserved, we wondered whether the differing binding properties of our three H. pylori isolates (Supplementary Fig. S1 and Fig. 2) could be attributed to diverging amino acid sequences. Interestingly, alignment of the KatA sequences of our three isolates and the reference strain H. pylori 22695 showed no differences in the relevant region between amino acid 350 and 400 (Supplementary Fig. S2). The differences in Vn binding might further be explained by a varying presence of KatA on the bacterial surface. We therefore employed flow cytometry analysis to determine KatA surface exposure in 11 of our previously tested strains including H. pylori CCUG18943, KR697, and KR497 (Supplementary Table 1). When the Vn-binding capacity was plotted against KatA surface expression we found a clear correlation of the two, i.e., overall, high Vn binders were also highly positive for KatA and vice versa (Fig. 6). We attribute the fact that some of our H. pylori isolates slightly diverged from this general pattern to the presence of other putative Vn-binding surface proteins in those particular strains. Taken together, our data demonstrate that the differences in KatA-dependent variations of Vn binding are not due to changes in the amino acid sequence of KatA but a result of varying surface exposure in addition to other putative Vn-binding proteins in some strains.


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)

Surface exposure of KatA correlates with Vn binding capacity.Eleven H. pylori isolates were tested for their Vn binding capacity and KatA surface density in separate flow cytometric assays. Data shown are the mean of at least three independent experiments. Linear regression was performed for all data points.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: Surface exposure of KatA correlates with Vn binding capacity.Eleven H. pylori isolates were tested for their Vn binding capacity and KatA surface density in separate flow cytometric assays. Data shown are the mean of at least three independent experiments. Linear regression was performed for all data points.
Mentions: Having identified the binding site for Vn within a flexible region, which are often less conserved, we wondered whether the differing binding properties of our three H. pylori isolates (Supplementary Fig. S1 and Fig. 2) could be attributed to diverging amino acid sequences. Interestingly, alignment of the KatA sequences of our three isolates and the reference strain H. pylori 22695 showed no differences in the relevant region between amino acid 350 and 400 (Supplementary Fig. S2). The differences in Vn binding might further be explained by a varying presence of KatA on the bacterial surface. We therefore employed flow cytometry analysis to determine KatA surface exposure in 11 of our previously tested strains including H. pylori CCUG18943, KR697, and KR497 (Supplementary Table 1). When the Vn-binding capacity was plotted against KatA surface expression we found a clear correlation of the two, i.e., overall, high Vn binders were also highly positive for KatA and vice versa (Fig. 6). We attribute the fact that some of our H. pylori isolates slightly diverged from this general pattern to the presence of other putative Vn-binding surface proteins in those particular strains. Taken together, our data demonstrate that the differences in KatA-dependent variations of Vn binding are not due to changes in the amino acid sequence of KatA but a result of varying surface exposure in addition to other putative Vn-binding proteins in some strains.

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