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Geographic distribution of methyltransferases of Helicobacter pylori: evidence of human host population isolation and migration.

Vale FF, Mégraud F, Vítor JM - BMC Microbiol. (2009)

Bottom Line: HhaI and M.NaeI, are likely conserved in H. pylori, and may have been present in the bacteria genome since the human diaspora out of Africa.This study indicates that some methyltransferases are useful geomarkers, which allow discrimination of bacterial populations, and that can be added to our tools to investigate human migrations.

View Article: PubMed Central - HTML - PubMed

Affiliation: Engineering Faculty, Portuguese Catholic University, Estrada Octávio Pato, 2635-631 Rio de Mouro, Portugal. filipavale@fe.lisboa.ucp.pt

ABSTRACT

Background: Helicobacter pylori colonizes the human stomach and is associated with gastritis, peptic ulcer, and gastric cancer. This ubiquitous association between H. pylori and humans is thought to be present since the origin of modern humans. The H. pylori genome encodes for an exceptional number of restriction and modifications (R-M) systems. To evaluate if R-M systems are an adequate tool to determine the geographic distribution of H. pylori strains, we typed 221 strains from Africa, America, Asia, and Europe, and evaluated the expression of different 29 methyltransferases.

Results: Independence tests and logistic regression models revealed that ten R-M systems correlate with geographical localization. The distribution pattern of these methyltransferases may have been originated by co-divergence of regional H. pylori after its human host migrated out of Africa. The expression of specific methyltransferases in the H. pylori population may also reflect the genetic and cultural background of its human host. Methyltransferases common to all strains, M. HhaI and M. NaeI, are likely conserved in H. pylori, and may have been present in the bacteria genome since the human diaspora out of Africa.

Conclusion: This study indicates that some methyltransferases are useful geomarkers, which allow discrimination of bacterial populations, and that can be added to our tools to investigate human migrations.

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Related in: MedlinePlus

Geographic distribution of H. pylori genomic methylation. MTases with specific geographic origin are in bold. Arrows indicate MTases that are associated with a strain from more than a continent, according to human migrations predicted by Cavalli-Sforza. Grey dashed lines indicate MTases, whose absence is significantly associated with continent of strain origin.
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Figure 1: Geographic distribution of H. pylori genomic methylation. MTases with specific geographic origin are in bold. Arrows indicate MTases that are associated with a strain from more than a continent, according to human migrations predicted by Cavalli-Sforza. Grey dashed lines indicate MTases, whose absence is significantly associated with continent of strain origin.

Mentions: It has been proposed that genes coding for R-M system were acquired recently, by horizontal gene transfer, with new systems being constantly acquired while old ones are inactivated or eliminated [27]. Our results support the hypothesis that at least some R-M systems were acquired since human migration out of Africa, while others were obtained later by geographically isolated bacterial populations. It is likely that the first MTases to be stably acquired by H. pylori genome were M. HhaI and M. NaeI, while the others were added later (Figure 1).


Geographic distribution of methyltransferases of Helicobacter pylori: evidence of human host population isolation and migration.

Vale FF, Mégraud F, Vítor JM - BMC Microbiol. (2009)

Geographic distribution of H. pylori genomic methylation. MTases with specific geographic origin are in bold. Arrows indicate MTases that are associated with a strain from more than a continent, according to human migrations predicted by Cavalli-Sforza. Grey dashed lines indicate MTases, whose absence is significantly associated with continent of strain origin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2749054&req=5

Figure 1: Geographic distribution of H. pylori genomic methylation. MTases with specific geographic origin are in bold. Arrows indicate MTases that are associated with a strain from more than a continent, according to human migrations predicted by Cavalli-Sforza. Grey dashed lines indicate MTases, whose absence is significantly associated with continent of strain origin.
Mentions: It has been proposed that genes coding for R-M system were acquired recently, by horizontal gene transfer, with new systems being constantly acquired while old ones are inactivated or eliminated [27]. Our results support the hypothesis that at least some R-M systems were acquired since human migration out of Africa, while others were obtained later by geographically isolated bacterial populations. It is likely that the first MTases to be stably acquired by H. pylori genome were M. HhaI and M. NaeI, while the others were added later (Figure 1).

Bottom Line: HhaI and M.NaeI, are likely conserved in H. pylori, and may have been present in the bacteria genome since the human diaspora out of Africa.This study indicates that some methyltransferases are useful geomarkers, which allow discrimination of bacterial populations, and that can be added to our tools to investigate human migrations.

View Article: PubMed Central - HTML - PubMed

Affiliation: Engineering Faculty, Portuguese Catholic University, Estrada Octávio Pato, 2635-631 Rio de Mouro, Portugal. filipavale@fe.lisboa.ucp.pt

ABSTRACT

Background: Helicobacter pylori colonizes the human stomach and is associated with gastritis, peptic ulcer, and gastric cancer. This ubiquitous association between H. pylori and humans is thought to be present since the origin of modern humans. The H. pylori genome encodes for an exceptional number of restriction and modifications (R-M) systems. To evaluate if R-M systems are an adequate tool to determine the geographic distribution of H. pylori strains, we typed 221 strains from Africa, America, Asia, and Europe, and evaluated the expression of different 29 methyltransferases.

Results: Independence tests and logistic regression models revealed that ten R-M systems correlate with geographical localization. The distribution pattern of these methyltransferases may have been originated by co-divergence of regional H. pylori after its human host migrated out of Africa. The expression of specific methyltransferases in the H. pylori population may also reflect the genetic and cultural background of its human host. Methyltransferases common to all strains, M. HhaI and M. NaeI, are likely conserved in H. pylori, and may have been present in the bacteria genome since the human diaspora out of Africa.

Conclusion: This study indicates that some methyltransferases are useful geomarkers, which allow discrimination of bacterial populations, and that can be added to our tools to investigate human migrations.

Show MeSH
Related in: MedlinePlus