Dynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans

ABSTRACT Helicobacter pylori undergoes rapid microevolution during chronic infection, but very little is known about how this affects host interaction factors. The best-studied adhesin of H. pylori is BabA, which mediates binding to the blood group antigen Lewis b [Le(b)]. To study the dynamics of L...

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Autores principales:	Sandra Nell, Lynn Kennemann, Sandra Schwarz, Christine Josenhans, Sebastian Suerbaum
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2014
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/a7506d84f80c4d6ab0bd373dfcbb8e2b
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spelling	oai:doaj.org-article:a7506d84f80c4d6ab0bd373dfcbb8e2b2021-11-15T15:47:04ZDynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans10.1128/mBio.02281-142150-7511https://doaj.org/article/a7506d84f80c4d6ab0bd373dfcbb8e2b2014-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02281-14https://doaj.org/toc/2150-7511ABSTRACT Helicobacter pylori undergoes rapid microevolution during chronic infection, but very little is known about how this affects host interaction factors. The best-studied adhesin of H. pylori is BabA, which mediates binding to the blood group antigen Lewis b [Le(b)]. To study the dynamics of Le(b) adherence during human infection, we analyzed paired H. pylori isolates obtained sequentially from chronically infected individuals. A complete loss or significant reduction of Le(b) binding was observed in strains from 5 out of 23 individuals, indicating that the Le(b) binding phenotype is quite stable during chronic human infection. Sequence comparisons of babA identified differences due to mutation and/or recombination in 12 out of 16 strain pairs analyzed. Most amino acid changes were found in the putative N-terminal extracellular adhesion domain. One strain pair that had changed from a Le(b) binding to a nonbinding phenotype was used to study the role of distinct sequence changes in Le(b) binding. By transformations of the nonbinding strain with a babA gene amplified from the binding strain, H. pylori strains with mosaic babA genes were generated. Recombinants were enriched for a gain of Le(b) binding by biopanning or for BabA expression on the bacterial surface by pulldown assay. With this approach, we identified several amino acid residues affecting the strength of Le(b) binding. Additionally, the data showed that the C terminus of BabA, which is predicted to encode an outer membrane β-barrel domain, plays an essential role in the biogenesis of this protein. IMPORTANCE Helicobacter pylori causes a chronic infection of the human stomach that can lead to ulcers and cancer. The bacterium can bind to gastric epithelial cells with specialized outer membrane proteins. The best-studied protein is the BabA adhesin which binds to the Lewis b blood group antigen. Since H. pylori is a bacterium with very high genetic variability, we asked whether babA evolves during chronic infection and how mutations or recombination in babA affect binding. We found that BabA-mediated adherence was stable in most individuals but observed a complete loss of binding or reduced binding in 22% of individuals. One strain pair in which binding was lost was used to generate babA sequences that were mosaics of a functional allele and a nonfunctional allele, and the mosaic sequences were used to identify amino acids critically involved in binding of BabA to Lewis b.Sandra NellLynn KennemannSandra SchwarzChristine JosenhansSebastian SuerbaumAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 5, Iss 6 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Sandra Nell Lynn Kennemann Sandra Schwarz Christine Josenhans Sebastian Suerbaum Dynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans
description	ABSTRACT Helicobacter pylori undergoes rapid microevolution during chronic infection, but very little is known about how this affects host interaction factors. The best-studied adhesin of H. pylori is BabA, which mediates binding to the blood group antigen Lewis b [Le(b)]. To study the dynamics of Le(b) adherence during human infection, we analyzed paired H. pylori isolates obtained sequentially from chronically infected individuals. A complete loss or significant reduction of Le(b) binding was observed in strains from 5 out of 23 individuals, indicating that the Le(b) binding phenotype is quite stable during chronic human infection. Sequence comparisons of babA identified differences due to mutation and/or recombination in 12 out of 16 strain pairs analyzed. Most amino acid changes were found in the putative N-terminal extracellular adhesion domain. One strain pair that had changed from a Le(b) binding to a nonbinding phenotype was used to study the role of distinct sequence changes in Le(b) binding. By transformations of the nonbinding strain with a babA gene amplified from the binding strain, H. pylori strains with mosaic babA genes were generated. Recombinants were enriched for a gain of Le(b) binding by biopanning or for BabA expression on the bacterial surface by pulldown assay. With this approach, we identified several amino acid residues affecting the strength of Le(b) binding. Additionally, the data showed that the C terminus of BabA, which is predicted to encode an outer membrane β-barrel domain, plays an essential role in the biogenesis of this protein. IMPORTANCE Helicobacter pylori causes a chronic infection of the human stomach that can lead to ulcers and cancer. The bacterium can bind to gastric epithelial cells with specialized outer membrane proteins. The best-studied protein is the BabA adhesin which binds to the Lewis b blood group antigen. Since H. pylori is a bacterium with very high genetic variability, we asked whether babA evolves during chronic infection and how mutations or recombination in babA affect binding. We found that BabA-mediated adherence was stable in most individuals but observed a complete loss of binding or reduced binding in 22% of individuals. One strain pair in which binding was lost was used to generate babA sequences that were mosaics of a functional allele and a nonfunctional allele, and the mosaic sequences were used to identify amino acids critically involved in binding of BabA to Lewis b.
format	article
author	Sandra Nell Lynn Kennemann Sandra Schwarz Christine Josenhans Sebastian Suerbaum
author_facet	Sandra Nell Lynn Kennemann Sandra Schwarz Christine Josenhans Sebastian Suerbaum
author_sort	Sandra Nell
title	Dynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans
title_short	Dynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans
title_full	Dynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans
title_fullStr	Dynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans
title_full_unstemmed	Dynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans
title_sort	dynamics of lewis b binding and sequence variation of the <italic toggle="yes">baba</italic> adhesin gene during chronic <named-content content-type="genus-species">helicobacter pylori</named-content> infection in humans
publisher	American Society for Microbiology
publishDate	2014
url	https://doaj.org/article/a7506d84f80c4d6ab0bd373dfcbb8e2b
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Dynamics of Lewis b Binding and Sequence Variation of the <italic toggle="yes">babA</italic> Adhesin Gene during Chronic <named-content content-type="genus-species">Helicobacter pylori</named-content> Infection in Humans

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