Tom Sandbox: Difference between revisions

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GCN4 (PDB [[2zta]] by itself, [[1ysa]] bound to DNA) is a eukaryotic transcription factor first isolated from Saccharomyces cerevisiae, also known as Baker's Yeast. The first 'leucine zipper' model was coined by Landshulz et al. in 1988. Today, while the name has stayed the same, we no longer view the leucine binding region in an inter-collated manner, but as <scene name='Tom_Sandbox/Leu-leu_interaction/1'>Leucines</scene> meeting face to face <ref name="abc"> Oas, T. G.; McIntosh, L. P.; O'Shea, E. K.; Dahlquist, F. W.; and Kim, P. S. Biochemistry 1990 29 (12), 2891-2894 </ref>. (see heptad repeat section) GCN4 binds to promoter regions AP-1 and ATF/CREB to induce transcription via the C terminal basic residues of the two symmetric alpha helices.<ref> Hope, I. A.; Struhl,K. Cell, Volume 46, Issue 6, 12 September 1986, Pages 885-894</ref>

===Structure===

GCN4 is composed of two identical 58 residue alpha helix chains that grouped together to form a parallel coiled-coil dimer. The dimer binds through interlocking leucine amino acids and hydrophobic residues near the C terminus, while pinching in on the major groove of DNA in the N terminal end via basic residues. These two main domains are thus labled the leucine zipper dimerization domain and the basic DNA-binding domain. <ref name="ph"> Sharma, G.; Rege, K.; Budil, D. E.; Yarmush, M. L.; Mavroidis, C. Int J Nanomedicine. 2008 December; 3(4): 505–521. </ref> The basic residues are the reason the class of binding interactions is commonly referred to as bZIP or basic region leucine zipper proteins<ref name="Voet"> Voet, Donald; Voet, Judith G.; Pratt, Charlotte W. Fundamentals of Biochemistry: Life at the Molecular Level. 3rd Ed. Hoboken, NJ: Wiley, 2008. </ref>. The X-ray structure of the 33-residue polypeptide corresponding to the leucine zipper of GCN4 was determined by Peter Kim and Thomas Alber<ref>PMID:1948029</ref>

GCN4 is composed of two identical 58 residue alpha helix chains that grouped together to form a parallel coiled-coil dimer. The dimer binds through interlocking leucine amino acids and hydrophobic residues near the C terminus, while pinching in on the major groove of DNA in the N terminal end via basic residues. These two main domains are thus labled the <scene name='Tom_Sandbox/Acidic_and_basic_regions/1'>acidic leucine zipper dimerization domain and the basic DNA-binding domain</scene>. <ref name="ph"> Sharma, G.; Rege, K.; Budil, D. E.; Yarmush, M. L.; Mavroidis, C. Int J Nanomedicine. 2008 December; 3(4): 505–521. </ref> Here the acidic region is represented as Orange and the basic region in purple. The basic residues are the reason the class of binding interactions is commonly referred to as bZIP or basic region leucine zipper proteins<ref name="Voet"> Voet, Donald; Voet, Judith G.; Pratt, Charlotte W. Fundamentals of Biochemistry: Life at the Molecular Level. 3rd Ed. Hoboken, NJ: Wiley, 2008. </ref>. The X-ray structure of the 33-residue polypeptide corresponding to the leucine zipper of GCN4 was determined by Peter Kim and Thomas Alber<ref>PMID:1948029</ref>

====Heptad Repeat====

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[[Image:Coiledcoil-wheelcartoon.gif|center|300px]]

~~{{STRUCTURE_1ysa| PDB=1ysa | SCENE= }}~~

'''Image 1:A pictorial representation of the heptad repeat between the two subunits in a coiled-coil conformation. By following through the wheels alphabetically, it is clear how the leucines will stack every 7 units. The apostrophe denotes the diference between the two polypeptide subunits.'''(from Kgutwin in Wikipedia Commons http://commons.wikimedia.org/wiki/File:Coiledcoil-wheelcartoon.gif)

At every d and d' we have a Leucine, while at the a and a' locations we typically see valine. <ref name="Voet" /> In the opposite positions one tends to see more charged and polar residues. The Leucine and Valine repeats create a strongly hydrophobic region between the two alpha helices. This clearly shows the relationship between coils and shown below, we can see that for the two helices to be symmetrical, the ~~<scene name='Tom_Sandbox/Leu-leu_interaction/1'>~~Leucines~~</scene>~~ must not in fact be oriented as a zipper, but on the same levels.

At every d and d' we have a Leucine, while at the a and a' locations we typically see valine. <ref name="Voet" /> In the opposite positions one tends to see more charged and polar residues. The Leucine and Valine repeats create a strongly hydrophobic region between the two alpha helices. This clearly shows the relationship between coils and shown below, we can see that for the two helices to be symmetrical, the Leucines must not in fact be oriented as a zipper, but on the same levels.

[[Image:Asymmetric_helices.jpg|center|400px]]

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@@ Line 7: / Line 7: @@
 GCN4 (PDB [[2zta]] by itself, [[1ysa]] bound to DNA) is a eukaryotic transcription factor first isolated from Saccharomyces cerevisiae, also known as Baker's Yeast. The first 'leucine zipper' model was coined by Landshulz et al. in 1988. Today, while the name has stayed the same, we no longer view the leucine binding region in an inter-collated manner, but as <scene name='Tom_Sandbox/Leu-leu_interaction/1'>Leucines</scene> meeting face to face <ref name="abc"> Oas, T. G.;  McIntosh, L. P.;  O'Shea, E. K.;  Dahlquist, F. W.; and  Kim, P. S. Biochemistry 1990 29 (12), 2891-2894 </ref>. (see heptad repeat section) GCN4 binds to promoter regions AP-1 and ATF/CREB to induce transcription via the C terminal basic residues of the two symmetric alpha helices.<ref> Hope, I. A.; Struhl,K. Cell, Volume 46, Issue 6, 12 September 1986, Pages 885-894</ref>
+{{STRUCTURE_1ysa|  PDB=1ysa  |  SCENE=  }}
 ===Structure===
-GCN4 is composed of two identical 58 residue alpha helix chains that grouped together to form a parallel coiled-coil dimer. The dimer binds through interlocking leucine amino acids and hydrophobic residues near the C terminus, while pinching in on the major groove of DNA in the N terminal end via basic residues. These two main domains are thus labled the leucine zipper dimerization domain and the basic DNA-binding domain. <ref name="ph"> Sharma, G.; Rege, K.; Budil, D. E.; Yarmush, M. L.; Mavroidis, C. Int J Nanomedicine. 2008 December; 3(4): 505–521. </ref> The basic residues are the reason the class of binding interactions is commonly referred to as bZIP or basic region leucine zipper proteins<ref name="Voet"> Voet, Donald; Voet, Judith G.; Pratt, Charlotte W. Fundamentals of Biochemistry: Life at the Molecular Level. 3rd Ed. Hoboken, NJ: Wiley, 2008. </ref>. The X-ray structure of the 33-residue polypeptide corresponding to the leucine zipper of GCN4 was determined by Peter Kim and Thomas Alber<ref>PMID:1948029</ref>
+GCN4 is composed of two identical 58 residue alpha helix chains that grouped together to form a parallel coiled-coil dimer. The dimer binds through interlocking leucine amino acids and hydrophobic residues near the C terminus, while pinching in on the major groove of DNA in the N terminal end via basic residues. These two main domains are thus labled the <scene name='Tom_Sandbox/Acidic_and_basic_regions/1'>acidic leucine zipper dimerization domain and the basic DNA-binding domain</scene>. <ref name="ph"> Sharma, G.; Rege, K.; Budil, D. E.; Yarmush, M. L.; Mavroidis, C. Int J Nanomedicine. 2008 December; 3(4): 505–521. </ref> Here the acidic region is represented as Orange and the basic region in purple. The basic residues are the reason the class of binding interactions is commonly referred to as bZIP or basic region leucine zipper proteins<ref name="Voet"> Voet, Donald; Voet, Judith G.; Pratt, Charlotte W. Fundamentals of Biochemistry: Life at the Molecular Level. 3rd Ed. Hoboken, NJ: Wiley, 2008. </ref>. The X-ray structure of the 33-residue polypeptide corresponding to the leucine zipper of GCN4 was determined by Peter Kim and Thomas Alber<ref>PMID:1948029</ref>
 ====Heptad Repeat====
@@ Line 18: / Line 25: @@
 [[Image:Coiledcoil-wheelcartoon.gif|center|300px]]
-{{STRUCTURE_1ysa|  PDB=1ysa  |  SCENE=  }}
 '''Image 1:A pictorial representation of the heptad repeat between the two subunits in a coiled-coil conformation. By following through the wheels alphabetically, it is clear how the leucines will stack every 7 units. The apostrophe denotes the diference between the two polypeptide subunits.'''(from Kgutwin in Wikipedia Commons http://commons.wikimedia.org/wiki/File:Coiledcoil-wheelcartoon.gif)
-At every d and d' we have a Leucine, while at the a and a' locations we typically see valine. <ref name="Voet" /> In the opposite positions one tends to see more charged and polar residues. The Leucine and Valine repeats create a strongly hydrophobic region between the two alpha helices. This clearly shows the relationship between coils and shown below, we can see that for the two helices to be symmetrical, the <scene name='Tom_Sandbox/Leu-leu_interaction/1'>Leucines</scene> must not in fact be oriented as a zipper, but on the same levels.
+At every d and d' we have a Leucine, while at the a and a' locations we typically see valine. <ref name="Voet" /> In the opposite positions one tends to see more charged and polar residues. The Leucine and Valine repeats create a strongly hydrophobic region between the two alpha helices. This clearly shows the relationship between coils and shown below, we can see that for the two helices to be symmetrical, the Leucines must not in fact be oriented as a zipper, but on the same levels.
 [[Image:Asymmetric_helices.jpg|center|400px]]