User:Nathan Harris/Tus: Difference between revisions
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'''Tus''' is a DNA binding protein involved in the termination of bi-directional replication in ''Escherichia coli''. Tus binds specifically to ''Ter'' sequences within the ''E. Coli'' genome forming a Tus- ''Ter'' complex which functions to trap replication forks. Tus binds to ''Ter'' sites as an asymmetric monomer creating a permissive and non-permissive face to allow for polar fork arrest <ref name = "Neylon"> | '''Tus''' is a DNA binding protein involved in the termination of bi-directional replication in ''Escherichia coli''. Tus binds specifically to ''Ter'' sequences within the ''E. Coli'' genome forming a Tus- ''Ter'' complex which functions to trap replication forks. Tus binds to ''Ter'' sites as an asymmetric monomer creating a permissive and non-permissive face to allow for polar fork arrest <ref name = "Neylon"> Neylon, C., Kralicek, A. V., Hill, T.M. and Dixon, N.E. (2005) Replication Termination in Escherichia coli: Structure and Antihelicase Activity of the Tus-Ter Complex. Microbiology and Molecular Biology, 69 (3): 501-526. | ||
</ref>. | </ref>. | ||
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=='''Structure of Tus protein and binding interactions with TerA'''== | =='''Structure of Tus protein and binding interactions with TerA'''== | ||
{{STRUCTURE_1ecr| PDB=1ecr | SCENE=User:Nathan_Harris/Tus/Opening_scene/1}} | {{STRUCTURE_1ecr| PDB=1ecr | SCENE=User:Nathan_Harris/Tus/Opening_scene/1}} | ||
Tus constitutes 308 amino acids and a mass of approximately 36 kDa. The structural components of Tus have been elucidated through crystal structures of Tus bound to <scene name='User:Nathan_Harris/Tus/Ter/1'>TerA</scene> <ref name = "Kamada" />. Tus exhibits a unique binding motif to Ter sites previously undescribed from any known protein-DNA interactions. | |||
Tus constitutes 308 amino acids and a mass of approximately 36 kDa. The structural components of Tus have been elucidated through crystal structures of Tus bound to <scene name='User:Nathan_Harris/Tus/Ter/1'>TerA</scene>. Tus exhibits a unique binding motif to Ter sites previously undescribed from any known protein-DNA interactions. | |||
Tus is divided into an <scene name='User:Nathan_Harris/Tus/Amino_domian/1'>amino domain</scene> and <scene name='User:Nathan_Harris/Tus/Carboxy_domain/1'>carboxy domain</scene> distinguished by two alpha helical regions and central β sheets combining to encompass a large central basic cleft. The <scene name='User:Nathan_Harris/Tus/Interdomain/2'>interdomain region</scene> consists of anti-parallel β strands and an <scene name='User:Nathan_Harris/Tus/L4/1'>extended L4 loop</scene> which connect the amino and carboxy domains. Within this interdomain region, the <scene name='User:Nathan_Harris/Tus/Bf/1'>βF</scene>, <scene name='User:Nathan_Harris/Tus/Bg/1'>βG</scene>, <scene name='User:Nathan_Harris/Tus/Bh/1'>βH</scene> and <scene name='User:Nathan_Harris/Tus/Bi/1'>βI</scene> strands are responsible for specific and non-specific recognition of ''Ter''. | Tus is divided into an <scene name='User:Nathan_Harris/Tus/Amino_domian/1'>amino domain</scene> and <scene name='User:Nathan_Harris/Tus/Carboxy_domain/1'>carboxy domain</scene> distinguished by two alpha helical regions and central β sheets combining to encompass a large central basic cleft. The <scene name='User:Nathan_Harris/Tus/Interdomain/2'>interdomain region</scene> consists of anti-parallel β strands and an <scene name='User:Nathan_Harris/Tus/L4/1'>extended L4 loop</scene> which connect the amino and carboxy domains. Within this interdomain region, the <scene name='User:Nathan_Harris/Tus/Bf/1'>βF</scene>, <scene name='User:Nathan_Harris/Tus/Bg/1'>βG</scene>, <scene name='User:Nathan_Harris/Tus/Bh/1'>βH</scene> and <scene name='User:Nathan_Harris/Tus/Bi/1'>βI</scene> strands are responsible for specific and non-specific recognition of ''Ter''. | ||
The amino domain consists of three amphipathic alpha helices forming an anti-parallel bundle roughly parallel to ''Ter'', a sandwich of anti-parallel β sheets and three loops. The major groove and minor groove are clamped by two alpha helices (<scene name='User:Nathan_Harris/Tus/A4/1'>αIV</scene> and <scene name='User:Nathan_Harris/Tus/A5/1'>αV</scene>) which also contribute to the hydrophobic core of the protein. Within the β sandwich, <scene name='User:Nathan_Harris/Tus/Bcadke/1'>βCADKE</scene> contacts the alpha helical region, whereas <scene name='User:Nathan_Harris/Tus/Blfij/1'>βLFIJ</scene> is associated with DNA binding. Furthermore, the extended L4 loop is also involved in contacts to the minor groove. | The amino domain consists of three amphipathic alpha helices forming an anti-parallel bundle roughly parallel to ''Ter'', a sandwich of anti-parallel β sheets and three loops. The major groove and minor groove are clamped by two alpha helices (<scene name='User:Nathan_Harris/Tus/A4/1'>αIV</scene> and <scene name='User:Nathan_Harris/Tus/A5/1'>αV</scene>) which also contribute to the hydrophobic core of the protein. Within the β sandwich, <scene name='User:Nathan_Harris/Tus/Bcadke/1'>βCADKE</scene> contacts the alpha helical region, whereas <scene name='User:Nathan_Harris/Tus/Blfij/1'>βLFIJ</scene> is associated with DNA binding. Furthermore, the extended L4 loop is also involved in contacts to the minor groove. | ||
The carboxy domain consists of a hydrophobic core stabilised by alpha helices and β strands (βGHNO). The <scene name='User:Nathan_Harris/Tus/L3/1'>L3 loop</scene> is responsible for connecting helices <scene name='User:Nathan_Harris/Tus/A6/1'>αVI</scene> and <scene name='User:Nathan_Harris/Tus/A7/1'>αVII</scene> and also contacts the minor groove of DNA. | The carboxy domain consists of a hydrophobic core stabilised by alpha helices and β strands (βGHNO). The <scene name='User:Nathan_Harris/Tus/L3/1'>L3 loop</scene> is responsible for connecting helices <scene name='User:Nathan_Harris/Tus/A6/1'>αVI</scene> and <scene name='User:Nathan_Harris/Tus/A7/1'>αVII</scene> and also contacts the minor groove of DNA <ref name = "Kamada" /> <ref name = "Neylon />. | ||