1y7y: Difference between revisions

Line 1:

[[Image:1y7y.gif|left|200px]]<br /><applet load="1y7y" size="~~450~~" color="white" frame="true" align="right" spinBox="true"

[[Image:1y7y.gif|left|200px]]<br /><applet load="1y7y" size="350" color="white" frame="true" align="right" spinBox="true"

caption="1y7y, resolution 1.69Å" />

'''High-resolution crystal structure of the restriction-modification controller protein C.AhdI from Aeromonas hydrophila'''<br />

==Overview==

Restriction-modification (R-M) systems serve to protect the host bacterium, from invading bacteriophage. The multi-component system includes a, methyltransferase, which recognizes and methylates a specific DNA, sequence, and an endonuclease which recognises the same sequence and, cleaves within or close to this site. The endonuclease will only cleave, DNA that is unmethylated at the specific site, thus host DNA is protected, while non-host DNA is cleaved. However, following DNA replication, expression of the endonuclease must be delayed until the host DNA is, appropriately methylated. In many R-M systems, this regulation is achieved, at the transcriptional level via the controller protein, or C-protein. We, have solved the first X-ray structure of an R-M controller protein, C.AhdI, to 1.69 A resolution using selenomethionine MAD. C.AhdI is part of, a Type IIH R-M system from the pathogen Aeromonas hydrophila. The, structure reveals an all-alpha protein that contains a classical, helix-turn-helix (HTH) domain and can be assigned to the Xre family of, transcriptional regulators. Unlike its monomeric structural homologues, an, extended helix generates an interface that results in dimerisation of the, free protein. The dimer is electrostatically polarised and a positively, charged surface corresponds to the position of the DNA recognition helices, of the HTH domain. Comparison with the structure of the lambda cI ternary, complex suggests that C.AhdI activates transcription through direct, contact with the sigma70 subunit of RNA polymerase.

Restriction-modification (R-M) systems serve to protect the host bacterium from invading bacteriophage. The multi-component system includes a methyltransferase, which recognizes and methylates a specific DNA sequence, and an endonuclease which recognises the same sequence and cleaves within or close to this site. The endonuclease will only cleave DNA that is unmethylated at the specific site, thus host DNA is protected while non-host DNA is cleaved. However, following DNA replication, expression of the endonuclease must be delayed until the host DNA is appropriately methylated. In many R-M systems, this regulation is achieved at the transcriptional level via the controller protein, or C-protein. We have solved the first X-ray structure of an R-M controller protein, C.AhdI, to 1.69 A resolution using selenomethionine MAD. C.AhdI is part of a Type IIH R-M system from the pathogen Aeromonas hydrophila. The structure reveals an all-alpha protein that contains a classical helix-turn-helix (HTH) domain and can be assigned to the Xre family of transcriptional regulators. Unlike its monomeric structural homologues, an extended helix generates an interface that results in dimerisation of the free protein. The dimer is electrostatically polarised and a positively charged surface corresponds to the position of the DNA recognition helices of the HTH domain. Comparison with the structure of the lambda cI ternary complex suggests that C.AhdI activates transcription through direct contact with the sigma70 subunit of RNA polymerase.

==About this Structure==

1Y7Y is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aeromonas_hydrophila Aeromonas hydrophila]. Full crystallographic information is available from [http://~~ispc~~.weizmann.ac.il/oca-bin/ocashort?id=1Y7Y OCA].

1Y7Y is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aeromonas_hydrophila Aeromonas hydrophila]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Y7Y OCA].

==Reference==

Line 13:

[[Category: Aeromonas hydrophila]]

[[Category: Single protein]]

[[Category: Fox, G.C.]]

[[Category: Fox, G C.]]

[[Category: Kneale, G.G.]]

[[Category: Kneale, G G.]]

[[Category: McGeehan, J.E.]]

[[Category: McGeehan, J E.]]

[[Category: Papapanagiotou, I.]]

[[Category: Streeter, S.D.]]

[[Category: Streeter, S D.]]

[[Category: dna-binding protein]]

[[Category: helix-turn-helix]]

[[Category: transcriptional regulator]]

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@@ Line 1: / Line 1: @@
-[[Image:1y7y.gif|left|200px]]<br /><applet load="1y7y" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1y7y.gif|left|200px]]<br /><applet load="1y7y" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1y7y, resolution 1.69&Aring;" />
 '''High-resolution crystal structure of the restriction-modification controller protein C.AhdI from Aeromonas hydrophila'''<br />
 ==Overview==
-Restriction-modification (R-M) systems serve to protect the host bacterium, from invading bacteriophage. The multi-component system includes a, methyltransferase, which recognizes and methylates a specific DNA, sequence, and an endonuclease which recognises the same sequence and, cleaves within or close to this site. The endonuclease will only cleave, DNA that is unmethylated at the specific site, thus host DNA is protected, while non-host DNA is cleaved. However, following DNA replication, expression of the endonuclease must be delayed until the host DNA is, appropriately methylated. In many R-M systems, this regulation is achieved, at the transcriptional level via the controller protein, or C-protein. We, have solved the first X-ray structure of an R-M controller protein, C.AhdI, to 1.69 A resolution using selenomethionine MAD. C.AhdI is part of, a Type IIH R-M system from the pathogen Aeromonas hydrophila. The, structure reveals an all-alpha protein that contains a classical, helix-turn-helix (HTH) domain and can be assigned to the Xre family of, transcriptional regulators. Unlike its monomeric structural homologues, an, extended helix generates an interface that results in dimerisation of the, free protein. The dimer is electrostatically polarised and a positively, charged surface corresponds to the position of the DNA recognition helices, of the HTH domain. Comparison with the structure of the lambda cI ternary, complex suggests that C.AhdI activates transcription through direct, contact with the sigma70 subunit of RNA polymerase.
+Restriction-modification (R-M) systems serve to protect the host bacterium from invading bacteriophage. The multi-component system includes a methyltransferase, which recognizes and methylates a specific DNA sequence, and an endonuclease which recognises the same sequence and cleaves within or close to this site. The endonuclease will only cleave DNA that is unmethylated at the specific site, thus host DNA is protected while non-host DNA is cleaved. However, following DNA replication, expression of the endonuclease must be delayed until the host DNA is appropriately methylated. In many R-M systems, this regulation is achieved at the transcriptional level via the controller protein, or C-protein. We have solved the first X-ray structure of an R-M controller protein, C.AhdI, to 1.69 A resolution using selenomethionine MAD. C.AhdI is part of a Type IIH R-M system from the pathogen Aeromonas hydrophila. The structure reveals an all-alpha protein that contains a classical helix-turn-helix (HTH) domain and can be assigned to the Xre family of transcriptional regulators. Unlike its monomeric structural homologues, an extended helix generates an interface that results in dimerisation of the free protein. The dimer is electrostatically polarised and a positively charged surface corresponds to the position of the DNA recognition helices of the HTH domain. Comparison with the structure of the lambda cI ternary complex suggests that C.AhdI activates transcription through direct contact with the sigma70 subunit of RNA polymerase.
 ==About this Structure==
-Y7Y is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aeromonas_hydrophila Aeromonas hydrophila]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1Y7Y OCA].
+Y7Y is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aeromonas_hydrophila Aeromonas hydrophila]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Y7Y OCA].
 ==Reference==
@@ Line 13: / Line 13: @@
 [[Category: Aeromonas hydrophila]]
 [[Category: Single protein]]
-[[Category: Fox, G.C.]]
+[[Category: Fox, G C.]]
-[[Category: Kneale, G.G.]]
+[[Category: Kneale, G G.]]
-[[Category: McGeehan, J.E.]]
+[[Category: McGeehan, J E.]]
 [[Category: Papapanagiotou, I.]]
-[[Category: Streeter, S.D.]]
+[[Category: Streeter, S D.]]
 [[Category: dna-binding protein]]
 [[Category: helix-turn-helix]]
 [[Category: transcriptional regulator]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Sun Nov 25 03:39:07 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:02:38 2008''