User:David McDonald/Replication Termination Protein

As with most bacteria, DNA replication of the circular chromosome of B. Subtilis occurs in a bi-directional fashion, starting from a common origin of replication (ori) and ending in the termination region, approximately 180o from the ori. The two replication forks are forced to meet in the termination region by replication termination proteins (RTPs) complexed to specific, unidirectional DNA termination sits (Ter sequences) termination region and arrest the action of the replication fork in a directional manner. That is, there are RTP:Ter complexes which stop replication in the clockwise and in the anti-clockwise direction. The clockwise replication fork is unaffected by the RTP:Ter complexes for the anti-clockwise fork and vice versa.

Structure

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RTP contains 122 amino acid residues and is an example of a winged helix structure, in the α+β protein folding family, containing four α-helices and two β-strands (1). In a cell, RTP exists as a homodimer, where the monomer subunits are tightly associated through antiparallel coiled-coil interactions between the C-terminal α-helices.

DNA Binding

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Asymmetric

Symmetric

one end

The other

Works Cited

1. Crystal structure of replication terminator protein of B. subtilis at 2.6 Å. Bussiere, DE, Bastia, D and White, SW. 80, 1995, Cell, pp. 651-660.

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David McDonald