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Molecular cloning and characterization of two Helicobacter pylori genes coding for plasminogen-binding proteins.

ABSTRACT: Helicobacter pylori binds a number of host cell proteins, including the plasma protein plasminogen, which is the proenzyme of the serine protease plasmin. Two H. pylori plasminogen-binding proteins have been described; however, no genes were identified. Here we report the use of a phage display library to clone two genes from the H. pylori CCUG 17874 genome that mediate binding to plasminogen. DNA sequence analysis of one of these genes revealed 96.6% homology with H. pylori 26695 HP0508. A subsequent database search revealed that the amino acid sequence of a lysine-rich C-terminal segment of HP0508 is identical to the C terminus of HP0863. Recombinant proteins expressed from HP0508 and HP0863 bound plasminogen specifically and in a lysine-dependent manner. We designate these genes pgbA and pgbB, respectively. These proteins are expressed by a variety of H. pylori strains, have surface-exposed domains, and do not inhibit plasminogen activation. These results indicate that pgbA and pgbB may allow H. pylori to coat its exterior with plasminogen, which subsequently can be activated to plasmin. The surface acquisition of protease activity may enhance the virulence of H. pylori.

SUBMITTER: Jonsson K

PROVIDER: S-EPMC357016 | biostudies-literature | 2004 Feb

REPOSITORIES: biostudies-literature

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Molecular cloning and characterization of two Helicobacter pylori genes coding for plasminogen-binding proteins.

Jönsson Klas K Guo Betty P BP Monstein Hans-Jürg HJ Mekalanos John J JJ Kronvall Göran G

Proceedings of the National Academy of Sciences of the United States of America 20040209 7

Helicobacter pylori binds a number of host cell proteins, including the plasma protein plasminogen, which is the proenzyme of the serine protease plasmin. Two H. pylori plasminogen-binding proteins have been described; however, no genes were identified. Here we report the use of a phage display library to clone two genes from the H. pylori CCUG 17874 genome that mediate binding to plasminogen. DNA sequence analysis of one of these genes revealed 96.6% homology with H. pylori 26695 HP0508. A subs ...[more]

PMID: 14769936

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Project description:Helicobacter pylori is one of the most common human pathogens. It causes chronic gastritis and is involved in the pathogenesis of gastroduodenal ulcer disease and possibly gastric carcinoma. Helicobacter mustelae is a bacterium closely related to H. pylori that causes gastritis and ulcer disease in ferrets and is therefore considered an important animal model of gastric Helicobacter infections. Motility, even in a viscous environment, is conferred to the bacteria by several sheathed flagella and is regarded as one of their principal virulence factors. The flagellar filament of H. pylori consists of two different flagellin species expressed in different amounts. The gene (flaA) encoding the major flagellin has recently been cloned and sequenced. Here we report the cloning and sequencing of two highly homologous new flagellin genes from H. pylori 85P and H. mustelae NCTC 12032. The nucleotide sequence of the H. pylori gene proved that it encoded the second flagellin molecule found in H. pylori flagellar filaments. The genes were named flaB. The H. mustelae and H. pylori flaB genes both coded for proteins with 514 amino acids and molecular masses of 54.0 and 53.9 kDa, respectively. The proteins shared 81.7% identical amino acids. The degree of conservation between H. pylori FlaB and the H. pylori FlaA major flagellin was much lower (58%). Both flaB genes were preceded by sigma 54-like promoter sequences. Mapping of the transcription start site for the H. pylori flaB gene by a primer extension experiment confirmed the functional activity of the sigma 54 promoter. To evaluate the importance of both genes for motility, flaA- and flaB-disrupted mutants of H. pylori N6 were constructed by electroporation-mediated allelic exchange and characterized by Western blot (immunoblot) analysis and motility testing. Both mutations selectively abolished the expression of the targeted gene without affecting the synthesis of the other flagellin molecule. Whereas flaA mutants were completely nonmotile, flaB mutants retained motility.

Dataset Information

Molecular cloning and characterization of two Helicobacter pylori genes coding for plasminogen-binding proteins.

Publications

Molecular cloning and characterization of two Helicobacter pylori genes coding for plasminogen-binding proteins.

Similar Datasets

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