RTP and Tus: Difference between revisions
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The structure of Tus is unusual for a DNA-binding protein. It binds ''Ter'' DNA as an asymmetrical monomer, which establishes the basis for its polar arrest of the replication fork. Tus has three distinct regions: two α-helical regions and central β-strands which jointly form a large, positively-charged central cleft (Kamada, 1996). The core β-structures embrace 13 base pairs of duplex DNA by partial insertion into the major groove, and at least 30 other residues make nonspecific contacts with the DNA backbone. | The structure of Tus is unusual for a DNA-binding protein. It binds ''Ter'' DNA as an asymmetrical monomer, which establishes the basis for its polar arrest of the replication fork. Tus has three distinct regions: two α-helical regions and central β-strands which jointly form a large, positively-charged central cleft (Kamada, 1996). The core β-structures embrace 13 base pairs of duplex DNA by partial insertion into the major groove, and at least 30 other residues make nonspecific contacts with the DNA backbone. | ||
The positioning of α-helices in the Tus protein is particularly interesting. Two protrude from both the amino and carboxy domains to clasp the DNA duplex, thereby shielding the interdomain β structures from direct contacts with other proteins (such as the DnaB helicase). The concentration of α-helices on the non-permissive face of Tus is absolutely cruical to the protein's ability to form a locked complex with the ''Ter'' site. More about this later! | The positioning of α-helices in the Tus protein is particularly interesting. Two protrude from both the amino and carboxy domains to clasp the DNA duplex, thereby shielding the interdomain β structures from direct contacts with other proteins (such as the DnaB helicase). The concentration of α-helices on the non-permissive face of Tus is absolutely cruical to the protein's ability to form a locked complex with the ''Ter'' site. More about this later! | ||
'''So how does Tus actually stop the replication fork? And why is it a polar arrest mechanism?''' | '''So how does Tus actually stop the replication fork? And why is it a polar arrest mechanism?''' | ||
