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Efficiency of purine utilization by Helicobacter pylori: roles for adenosine deaminase and a NupC homolog.

Miller EF, Vaish S, Maier RJ - PLoS ONE (2012)

Bottom Line: Helicobacter pylori colonizes the gastric epithelium of humans, yet its specific purine requirements are poorly understood, and the transport mechanisms underlying purine uptake remain unknown.Doubling times in this medium varied between 7 and 14 hours depending on the purine source, with hypoxanthine, inosine and adenosine representing the purines utilized most efficiently for growth.Deletion of the GMP biosynthesis gene guaA had no discernible effect on mouse stomach colonization, in contrast to findings in numerous bacterial pathogens.

View Article: PubMed Central - PubMed

Affiliation: Microbiology Department, The University of Georgia, Athens, Georgia, United States of America.

ABSTRACT
The ability to synthesize and salvage purines is crucial for colonization by a variety of human bacterial pathogens. Helicobacter pylori colonizes the gastric epithelium of humans, yet its specific purine requirements are poorly understood, and the transport mechanisms underlying purine uptake remain unknown. Using a fully defined synthetic growth medium, we determined that H. pylori 26695 possesses a complete salvage pathway that allows for growth on any biological purine nucleobase or nucleoside with the exception of xanthosine. Doubling times in this medium varied between 7 and 14 hours depending on the purine source, with hypoxanthine, inosine and adenosine representing the purines utilized most efficiently for growth. The ability to grow on adenine or adenosine was studied using enzyme assays, revealing deamination of adenosine but not adenine by H. pylori 26695 cell lysates. Using mutant analysis we show that a strain lacking the gene encoding a NupC homolog (HP1180) was growth-retarded in a defined medium supplemented with certain purines. This strain was attenuated for uptake of radiolabeled adenosine, guanosine, and inosine, showing a role for this transporter in uptake of purine nucleosides. Deletion of the GMP biosynthesis gene guaA had no discernible effect on mouse stomach colonization, in contrast to findings in numerous bacterial pathogens. In this study we define a more comprehensive model for purine acquisition and salvage in H. pylori that includes purine uptake by a NupC homolog and catabolism of adenosine via adenosine deaminase.

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Sequence comparison between H. pylori NupC homolog (HP1180) and three E. coli CNT paralogs.Sequences for E. coli YeiJ (GenBankTM accession number AAA60513.1), E. coli YeiM (GenBankTM accession number AAA60518.1), HP1180 (GenBankTM accession number AAD08224.1), and E. coli NupC (GenBankTM accession number CAA52821.1) were aligned using ClustalW. Membrane-spanning helices were predicted using the TMHMM program [46]. Conserved regions typical of CNT transporters are boxed in black [34].
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pone-0038727-g004: Sequence comparison between H. pylori NupC homolog (HP1180) and three E. coli CNT paralogs.Sequences for E. coli YeiJ (GenBankTM accession number AAA60513.1), E. coli YeiM (GenBankTM accession number AAA60518.1), HP1180 (GenBankTM accession number AAD08224.1), and E. coli NupC (GenBankTM accession number CAA52821.1) were aligned using ClustalW. Membrane-spanning helices were predicted using the TMHMM program [46]. Conserved regions typical of CNT transporters are boxed in black [34].

Mentions: HP1180 from H. pylori 26695 is a member of the CNT family of nucleoside transporters, and is present in all sequenced H. pylori strains. An amino acid sequence alignment compares HP1180 against E. coli NupC (Figure 4). The latter protein transports pyrimidine nucleosides and adenosine, but does not transport guanosine or nucleobases, and transports inosine inefficiently [16]. Two other E. coli CNT transporters of unknown substrate specificity YeiJ (NupX) and YeiM and are included in the alignment.


Efficiency of purine utilization by Helicobacter pylori: roles for adenosine deaminase and a NupC homolog.

Miller EF, Vaish S, Maier RJ - PLoS ONE (2012)

Sequence comparison between H. pylori NupC homolog (HP1180) and three E. coli CNT paralogs.Sequences for E. coli YeiJ (GenBankTM accession number AAA60513.1), E. coli YeiM (GenBankTM accession number AAA60518.1), HP1180 (GenBankTM accession number AAD08224.1), and E. coli NupC (GenBankTM accession number CAA52821.1) were aligned using ClustalW. Membrane-spanning helices were predicted using the TMHMM program [46]. Conserved regions typical of CNT transporters are boxed in black [34].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368855&req=5

pone-0038727-g004: Sequence comparison between H. pylori NupC homolog (HP1180) and three E. coli CNT paralogs.Sequences for E. coli YeiJ (GenBankTM accession number AAA60513.1), E. coli YeiM (GenBankTM accession number AAA60518.1), HP1180 (GenBankTM accession number AAD08224.1), and E. coli NupC (GenBankTM accession number CAA52821.1) were aligned using ClustalW. Membrane-spanning helices were predicted using the TMHMM program [46]. Conserved regions typical of CNT transporters are boxed in black [34].
Mentions: HP1180 from H. pylori 26695 is a member of the CNT family of nucleoside transporters, and is present in all sequenced H. pylori strains. An amino acid sequence alignment compares HP1180 against E. coli NupC (Figure 4). The latter protein transports pyrimidine nucleosides and adenosine, but does not transport guanosine or nucleobases, and transports inosine inefficiently [16]. Two other E. coli CNT transporters of unknown substrate specificity YeiJ (NupX) and YeiM and are included in the alignment.

Bottom Line: Helicobacter pylori colonizes the gastric epithelium of humans, yet its specific purine requirements are poorly understood, and the transport mechanisms underlying purine uptake remain unknown.Doubling times in this medium varied between 7 and 14 hours depending on the purine source, with hypoxanthine, inosine and adenosine representing the purines utilized most efficiently for growth.Deletion of the GMP biosynthesis gene guaA had no discernible effect on mouse stomach colonization, in contrast to findings in numerous bacterial pathogens.

View Article: PubMed Central - PubMed

Affiliation: Microbiology Department, The University of Georgia, Athens, Georgia, United States of America.

ABSTRACT
The ability to synthesize and salvage purines is crucial for colonization by a variety of human bacterial pathogens. Helicobacter pylori colonizes the gastric epithelium of humans, yet its specific purine requirements are poorly understood, and the transport mechanisms underlying purine uptake remain unknown. Using a fully defined synthetic growth medium, we determined that H. pylori 26695 possesses a complete salvage pathway that allows for growth on any biological purine nucleobase or nucleoside with the exception of xanthosine. Doubling times in this medium varied between 7 and 14 hours depending on the purine source, with hypoxanthine, inosine and adenosine representing the purines utilized most efficiently for growth. The ability to grow on adenine or adenosine was studied using enzyme assays, revealing deamination of adenosine but not adenine by H. pylori 26695 cell lysates. Using mutant analysis we show that a strain lacking the gene encoding a NupC homolog (HP1180) was growth-retarded in a defined medium supplemented with certain purines. This strain was attenuated for uptake of radiolabeled adenosine, guanosine, and inosine, showing a role for this transporter in uptake of purine nucleosides. Deletion of the GMP biosynthesis gene guaA had no discernible effect on mouse stomach colonization, in contrast to findings in numerous bacterial pathogens. In this study we define a more comprehensive model for purine acquisition and salvage in H. pylori that includes purine uptake by a NupC homolog and catabolism of adenosine via adenosine deaminase.

Show MeSH
Related in: MedlinePlus