A type IV modification dependent restriction nuclease that targets glucosylated hydroxymethyl cytosine modified DNAs.
J Mol Biol
; 366(3): 768-78, 2007 Feb 23.
Article
em En
| MEDLINE
| ID: mdl-17188297
ABSTRACT
The Escherichia coli CT596 prophage exclusion genes gmrS and gmrD were found to encode a novel type IV modification-dependent restriction nuclease that targets and digests glucosylated (glc)-hydroxymethylcytosine (HMC) DNAs. The protein products GmrS (36 kDa) and GmrD (27 kDa) were purified and found to be inactive separately, but together degraded several different glc-HMC modified DNAs (T4, T2 and T6). The GMR enzyme is able to degrade both alpha-glucosy-HMC T4 DNA and beta-glucosyl-HMC T4 DNA, whereas no activity was observed against non-modified DNAs including unmodified T4 cytosine (C) DNA or non-glucosylated T4 HMC DNA. Enzyme activity requires NTP, favors UTP, is stimulated by calcium, and initially produces 4 kb DNA fragments that are further degraded to low molecular mass products. The enzyme is inhibited by the T4 phage internal protein I* (IPI*) to which it was found to bind. Overall activities of the purified GmrSD enzyme are in good agreement with the properties of the cloned gmr genes in vivo and suggest a restriction enzyme specific for sugar modified HMC DNAs. IPI* thus represents a third generation bacteriophage defense against restriction nucleases of the Gmr type.
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Base de dados:
MEDLINE
Assunto principal:
DNA Viral
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Enzimas de Restrição do DNA
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Proteínas de Escherichia coli
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Citosina
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Escherichia coli
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article