1ka8

<table><tr><td colspan='2'>[[1ka8]] is a 6 chain structure with sequence from [http://en.wikipedia.org/wiki/Bpp4 Bpp4]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KA8 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1KA8 FirstGlance]. <br>

</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ka8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ka8 OCA], [http://pdbe.org/1ka8 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1ka8 RCSB], [http://www.ebi.ac.uk/pdbsum/1ka8 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1ka8 ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/PRIM_BPP4 PRIM_BPP4]] This protein acts as a DNA primase generating di- to pentaribonucleotides; the predominant product being the dimer pppApG. It complexes specifically to the P4 origin of replication (ori) and its cis replication region (crr). It also acts as a DNA helicase.

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== Publication Abstract from PubMed ==

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.

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<ref>PMID:11929537</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 1ka8" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Bpp4]]

[[Category: Calendar, R]]

[[Category: Korolev, S]]

[[Category: Lanka, E]]

[[Category: Waksman, G]]

[[Category: Yeo, H J]]

[[Category: Ziegelin, G]]

[[Category: Winged helix]]