1ka8
From Proteopedia
(New page: 200px<br /><applet load="1ka8" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ka8, resolution 2.95Å" /> '''Crystal Structure of...) |
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| - | [[Image:1ka8.jpg|left|200px]]<br /><applet load="1ka8" size=" | + | [[Image:1ka8.jpg|left|200px]]<br /><applet load="1ka8" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ka8, resolution 2.95Å" /> | caption="1ka8, resolution 2.95Å" /> | ||
'''Crystal Structure of the Phage P4 Origin-Binding Domain'''<br /> | '''Crystal Structure of the Phage P4 Origin-Binding Domain'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The origin-binding domain of the gpalpha protein of phage P4 (P4-OBD) | + | The origin-binding domain of the gpalpha protein of phage P4 (P4-OBD) mediates origin recognition and regulation of gpalpha activity by the protein Cnr. We have determined the crystal structure of P4-OBD at 2.95 A resolution. The structure of P4-OBD is that of a dimer with pseudo twofold symmetry. Each subunit has a winged helix topology with a unique structure among initiator proteins. The only structural homologue of the P4-OBD subunit is the DNA-binding domain of the eukaryotic transcriptional activator Rfx1. Based on this structural alignment, a model for origin recognition by the P4-OBD dimer is suggested. P4-OBD mutations that interfere with Cnr binding locate to the dimer interface, indicating that Cnr acts by disrupting the gpalpha dimer. P4-OBD dimerization is mediated by helices alpha1 and alpha3 in both subunits, a mode of winged helix protein dimerization that is reminiscent of that of the eukaryotic transcription factors E2F and DP. This, in turn, suggests that Cnr is also a winged helix protein, a possibility that is supported by previously unreported sequence homologies between Cnr and Rfx1 and homology modelling. Hence, in a mechanism that appears to be conserved from phage to man, the DNA-binding activity of winged helix proteins can be regulated by other winged helix proteins via the versatile use of the winged helix motif as a homo- or heterodimerization scaffold. |
==About this Structure== | ==About this Structure== | ||
| - | 1KA8 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Enterobacteria_phage_p21 Enterobacteria phage p21]. Full crystallographic information is available from [http:// | + | 1KA8 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Enterobacteria_phage_p21 Enterobacteria phage p21]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KA8 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Lanka, E.]] | [[Category: Lanka, E.]] | ||
[[Category: Waksman, G.]] | [[Category: Waksman, G.]] | ||
| - | [[Category: Yeo, H | + | [[Category: Yeo, H J.]] |
[[Category: Ziegelin, G.]] | [[Category: Ziegelin, G.]] | ||
[[Category: winged helix]] | [[Category: winged helix]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:31:50 2008'' |
Revision as of 11:31, 21 February 2008
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Crystal Structure of the Phage P4 Origin-Binding Domain
Overview
The origin-binding domain of the gpalpha protein of phage P4 (P4-OBD) mediates origin recognition and regulation of gpalpha activity by the protein Cnr. We have determined the crystal structure of P4-OBD at 2.95 A resolution. The structure of P4-OBD is that of a dimer with pseudo twofold symmetry. Each subunit has a winged helix topology with a unique structure among initiator proteins. The only structural homologue of the P4-OBD subunit is the DNA-binding domain of the eukaryotic transcriptional activator Rfx1. Based on this structural alignment, a model for origin recognition by the P4-OBD dimer is suggested. P4-OBD mutations that interfere with Cnr binding locate to the dimer interface, indicating that Cnr acts by disrupting the gpalpha dimer. P4-OBD dimerization is mediated by helices alpha1 and alpha3 in both subunits, a mode of winged helix protein dimerization that is reminiscent of that of the eukaryotic transcription factors E2F and DP. This, in turn, suggests that Cnr is also a winged helix protein, a possibility that is supported by previously unreported sequence homologies between Cnr and Rfx1 and homology modelling. Hence, in a mechanism that appears to be conserved from phage to man, the DNA-binding activity of winged helix proteins can be regulated by other winged helix proteins via the versatile use of the winged helix motif as a homo- or heterodimerization scaffold.
About this Structure
1KA8 is a Single protein structure of sequence from Enterobacteria phage p21. Full crystallographic information is available from OCA.
Reference
Phage P4 origin-binding domain structure reveals a mechanism for regulation of DNA-binding activity by homo- and heterodimerization of winged helix proteins., Yeo HJ, Ziegelin G, Korolev S, Calendar R, Lanka E, Waksman G, Mol Microbiol. 2002 Feb;43(4):855-67. PMID:11929537
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