The Helicobacter pylori HpyAXII restriction-modification system limits exogenous DNA uptake by targeting GTAC sites but shows asymmetric conservation of the DNA methyltransferase and restriction endonuclease components.

ABSTRACT: The naturally competent organism Helicobacter pylori encodes a large number of restriction-modification (R-M) systems that consist of a restriction endonuclease and a DNA methyltransferase. R-M systems are not only believed to limit DNA exchange among bacteria but may also have other cellular functions. We report a previously uncharacterized H. pylori type II R-M system, M.HpyAXII/R.HpyAXII. We show that this system targets GTAC sites, which are rare in the H. pylori chromosome but numerous in ribosomal RNA genes. As predicted, this type II R-M system showed attributes of a selfish element. Deletion of the methyltransferase M.HpyAXII is lethal when associated with an active endonuclease R.HpyAXII unless compensated by adaptive mutation or gene amplification. R.HpyAXII effectively restricte

SUBMITTER: Humbert O 

PROVIDER: S-EPMC2588503 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature