Lauren Ferris/Sandbox 2

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[[Image:Pentamer-pentamer.jpg|300px|left|thumb|Model of the pentamer-pentamer structure. (PDB: [[4HQB]]) This figure was generated using Pymol.]]
[[Image:Pentamer-pentamer.jpg|300px|left|thumb|Model of the pentamer-pentamer structure. (PDB: [[4HQB]]) This figure was generated using Pymol.]]
Recently, a structure for Deinococcus radiodurans in complex with ssDNA has been solved.<ref>PMID: 23975200 </ref> The structure revealed that ssDNA bind in two clefts between three subunits. One 4 base pair strand of DT bound in the cleft between E and A, while the other 4 base pair strand of DT bound between A and B. Interestingly, when symmetry was applied to the crystal the dT strands appeared continuous. <ref>PMID: 23975200 </ref>
Recently, a structure for Deinococcus radiodurans in complex with ssDNA has been solved.<ref>PMID: 23975200 </ref> The structure revealed that ssDNA bind in two clefts between three subunits. One 4 base pair strand of DT bound in the cleft between E and A, while the other 4 base pair strand of DT bound between A and B. Interestingly, when symmetry was applied to the crystal the dT strands appeared continuous. <ref>PMID: 23975200 </ref>
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[[Image:DNA channel.jpg|300px|left|thumb|Two pentamers associate forming a channel for the ssDNA to thread through. (PDB: [[4HQB]]) This figure was generated using Pymol.]]
 
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The crystal structure also determined that the pentameric ring binds to another pentameric ring. Given the continuous chain formed by the DT strands it appears that the chain passes through the channel formed by subunits A and E in one pentamer. (which will now be referred to as A1 and E1). To pass through the channel in the second pentamer between A and B (now A2 and B2). In this direction the DNA strand runs in the 5’ to 3’ direction.<ref>PMID: 23975200 </ref>
 
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[[Image:DNA channel.jpg|300px|left|thumb|Two pentamers associate forming a channel for the ssDNA to thread through. (PDB: [[4HQB]]) This figure was generated using Pymol.]]
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The crystal structure also determined that the pentameric ring binds to another pentameric ring. Given the continuous chain formed by the DT strands it appears that the chain passes through the channel formed by subunits A and E in one pentamer. (which will now be referred to as A1 and E1). To pass through the channel in the second pentamer between A and B (now A2 and B2). In this direction the DNA strand runs in the 5’ to 3’ direction.<ref>PMID: 23975200 </ref>
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[[Image:t7-8.jpg|300px|left|thumb|Interactions between DdrB and T7 and T8. (PDB: [[4HQB]]) This figure was generated using Pymol.]]'''Nucleotides 7 and 8 (T7 and T8 respectively):''' Interact with Chains A2 and B2
[[Image:t7-8.jpg|300px|left|thumb|Interactions between DdrB and T7 and T8. (PDB: [[4HQB]]) This figure was generated using Pymol.]]'''Nucleotides 7 and 8 (T7 and T8 respectively):''' Interact with Chains A2 and B2
The 5’ phosphate of T7 hydrogen bonds with K94 of chain A and R132 of chain A. T7 forms pi-pi interactions with W66 of chain B and forms a hydrogen bond with K96. T8 is stabilized by a hydrophobic patch on the B6’-B7’ hairpin (V90 chain A. Phosphate groups of T8 stabilized through hydrogen bonding with A81, H80, and G106. <ref>PMID: 23975200 </ref>
The 5’ phosphate of T7 hydrogen bonds with K94 of chain A and R132 of chain A. T7 forms pi-pi interactions with W66 of chain B and forms a hydrogen bond with K96. T8 is stabilized by a hydrophobic patch on the B6’-B7’ hairpin (V90 chain A. Phosphate groups of T8 stabilized through hydrogen bonding with A81, H80, and G106. <ref>PMID: 23975200 </ref>
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==Related Proteins==
==Related Proteins==
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[[Image:Alignment.jpg|300px|left|thumb| Alignment of the crystal structures of Deinococcus radiodurans and Deinococcus geothermalis. (A.) Alignment of chains c, (B.) Alignment of Chains a with DNA, (C.) Alignment of the pentamer. (PDB: [[4EXW]] and [[4HQB]]) This figure was generated using Pymol.]]
DdrB is unique to the genus Deinococcus and shares very few similarities with other ssDNA binding proteins. As mentioned above, many ssDNA binding proteins function through an OB fold. However, this fold is missing in DdrB and Ddrb present a novel ssDNA binding mechanism.
DdrB is unique to the genus Deinococcus and shares very few similarities with other ssDNA binding proteins. As mentioned above, many ssDNA binding proteins function through an OB fold. However, this fold is missing in DdrB and Ddrb present a novel ssDNA binding mechanism.
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Within the Deinococcus genus, DdrB is relatively conserved between species. The crystal structures of Deinococcus radiodurans and Deinococcus geothermalis are quite similar. However, there are some differences in the regions connecting B6-B7 and B7-B8. This difference may be due to difference in stability, the DNA present in the Deinococcus radiodurans structure may provide stabilize this part of the structure leading to the discrepancy.<ref>PMID: 23975200 </ref> [[Image:Alignment.jpg|300px|left|thumb| Alignment of the crystal structures of Deinococcus radiodurans and Deinococcus geothermalis. (A.) Alignment of chains c, (B.) Alignment of Chains a with DNA, (C.) Alignment of the pentamer. (PDB: [[4EXW]] and [[4HQB]]) This figure was generated using Pymol.]]
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Within the Deinococcus genus, DdrB is relatively conserved between species. The crystal structures of Deinococcus radiodurans and Deinococcus geothermalis are quite similar. However, there are some differences in the regions connecting B6-B7 and B7-B8. This difference may be due to difference in stability, the DNA present in the Deinococcus radiodurans structure may provide stabilize this part of the structure leading to the discrepancy.<ref>PMID: 23975200 </ref>
there may also be similarities between DdrB and another Deinococcus DNA binding protein DdrA - however, more research is needed on the latter protein before any conclusions can be made. <ref>PMID: 23975200 </ref>
there may also be similarities between DdrB and another Deinococcus DNA binding protein DdrA - however, more research is needed on the latter protein before any conclusions can be made. <ref>PMID: 23975200 </ref>

Revision as of 12:13, 30 April 2014

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