Escherichia coli/Methylation

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(New page: *Type I methylation systems: ** ''E. coli'' K-12 restricts DNA which is '''not''' protected by adenine methylation at sites AA<sup>*</sup>C[N<sub>6</sub>]GTGC or GCA<sup>*</sup>C[N<sub>6<...)
Current revision (21:52, 4 April 2013) (view source)
(Minor fixes.)
 
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*Type I methylation systems:
*Type I methylation systems:
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** ''E. coli'' K-12 restricts DNA which is '''not''' protected by adenine methylation at sites AA<sup>*</sup>C[N<sub>6</sub>]GTGC  or GCA<sup>*</sup>C[N<sub>6</sub>]GTT, encoded by the hsdRMS genes(EcoKI).  Deletions in these genes removes either the restriction or methylation or both of these functions.
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** ''E. coli'' K12 restricts DNA which is '''not''' protected by adenine methylation at sites AA<sup>*</sup>C[N<sub>6</sub>]GTGC  or GCA<sup>*</sup>C[N<sub>6</sub>]GTT, encoded by the hsdRMS genes(EcoKI).  Deletions in these genes removes either the restriction or methylation or both of these functions.
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** ''E. coli'' B derivative strains contain an hsdRMS system (EcoBI) restricting and protectiing the sequence TGA<sup>*</sup>[N<sub>8</sub>]TGCT or AGCA<sup>*</sup>[N<sub>8</sub>]TCA.
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** ''E. coli'' B derivative strains contain an hsdRMS system (EcoBI) restricting and protecting the sequence TGA<sup>*</sup>[N<sub>8</sub>]TGCT or AGCA<sup>*</sup>[N<sub>8</sub>]TCA.
* The '''mcrA''' gene (carried on the e14 prophage)  restricts DNA which '''is''' methylated in C<sup>m</sup>CWGG or <sup>m</sup>CG sequences (methylation by the '''dcm''' gene product).
* The '''mcrA''' gene (carried on the e14 prophage)  restricts DNA which '''is''' methylated in C<sup>m</sup>CWGG or <sup>m</sup>CG sequences (methylation by the '''dcm''' gene product).
* The '''mcrBC''' genes restrict  R<sup>m</sup>C sequences.  
* The '''mcrBC''' genes restrict  R<sup>m</sup>C sequences.  
* The '''mrr''' gene product restricts adenine methylated sequences at CAG or GAC sites.
* The '''mrr''' gene product restricts adenine methylated sequences at CAG or GAC sites.
* E. coli methylates the adenine in GATC (and the corresponding A on the opposite strand) with the '''dam''' gene product.
* E. coli methylates the adenine in GATC (and the corresponding A on the opposite strand) with the '''dam''' gene product.
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* M.EcoKII methylates the first A at the palindromic site ATGCAT (as well as the corresponding A on the opposite strand), see (Kossykh VG (2004)  J. Bact 186: 2061-2067 PMID 15028690)  Note that this article has been retracted; the retraction appears to center on textual plagarism, not experimental results.  The homology to AvaIII is real.  I think I believe it. [[User:Tk|tk]] 20:28, 9 December 2005 (EST).  Rich Roberts reports: "We have tried ourselves to detect activity with this gene product and cannot detect any methyltransferase activity.  In our case we used antibodies able  to detect N6-methyladenine or N4 methylcytosine in DNA.  The ones we have are very sensitive and should have been able to detect 5 methyl groups in the whole E. coli chromosome.  Nothing was detected in an over expressing strain."
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* M.EcoKII methylates the first A at the palindromic site ATGCAT (as well as the corresponding A on the opposite strand), see (Kossykh VG (2004)  J. Bact 186: 2061-2067 PMID 15028690)  Note that this article has been retracted; the retraction appears to center on textual plagarism, not experimental results.  The homology to AvaIII is real.  I think I believe it. [[User:Tk|tk]] 20:28, 9 December 2005 (EST).  Rich Roberts reports: "We have tried ourselves to detect activity with this gene product and cannot detect any methyltransferase activity.  In our case we used antibodies able  to detect N6-methyladenine or N4 methylcytosine in DNA.  The ones we have are very sensitive and should have been able to detect <font color=purple>5-methyl</font> groups in the whole E. coli chromosome.  Nothing was detected in an over-expressing strain."
*For additional information see [[E. coli restriction-modification system]] and the [http://www.neb.com/nebecomm/tech_reference/restriction_enzymes/making_unmethylated_dna.asp NEB technical information on methylation].
*For additional information see [[E. coli restriction-modification system]] and the [http://www.neb.com/nebecomm/tech_reference/restriction_enzymes/making_unmethylated_dna.asp NEB technical information on methylation].
[[Category:Escherichia coli]]
[[Category:Escherichia coli]]

Current revision

  • Type I methylation systems:
    • E. coli K12 restricts DNA which is not protected by adenine methylation at sites AA*C[N6]GTGC or GCA*C[N6]GTT, encoded by the hsdRMS genes(EcoKI). Deletions in these genes removes either the restriction or methylation or both of these functions.
    • E. coli B derivative strains contain an hsdRMS system (EcoBI) restricting and protecting the sequence TGA*[N8]TGCT or AGCA*[N8]TCA.
  • The mcrA gene (carried on the e14 prophage) restricts DNA which is methylated in CmCWGG or mCG sequences (methylation by the dcm gene product).
  • The mcrBC genes restrict RmC sequences.
  • The mrr gene product restricts adenine methylated sequences at CAG or GAC sites.
  • E. coli methylates the adenine in GATC (and the corresponding A on the opposite strand) with the dam gene product.
  • M.EcoKII methylates the first A at the palindromic site ATGCAT (as well as the corresponding A on the opposite strand), see (Kossykh VG (2004) J. Bact 186: 2061-2067 PMID 15028690) Note that this article has been retracted; the retraction appears to center on textual plagarism, not experimental results. The homology to AvaIII is real. I think I believe it. tk 20:28, 9 December 2005 (EST). Rich Roberts reports: "We have tried ourselves to detect activity with this gene product and cannot detect any methyltransferase activity. In our case we used antibodies able to detect N6-methyladenine or N4 methylcytosine in DNA. The ones we have are very sensitive and should have been able to detect 5-methyl groups in the whole E. coli chromosome. Nothing was detected in an over-expressing strain."
  • For additional information see E. coli restriction-modification system and the NEB technical information on methylation.
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