The replication terminator protein (RTP) is a DNA-binding protein that helps terminate

DNA replication In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all life, living organisms, acting as the most essential part of heredity, biolog ...

in ''

Bacillus ''Bacillus'', from Latin "bacillus", meaning "little staff, wand", is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-sh ...

''. It has a winged-helix structure and forms a

homodimer In biochemistry, a protein dimer is a macromolecular complex or protein multimer, multimer formed by two protein monomers, or single proteins, which are usually Non-covalent interaction, non-covalently bound. Many macromolecules, such as proteins ...

via hydrogen bonds. The dimer is symmetric when it is not bound to DNA, but becomes asymmetrical when it is bound. Its termination activity is polar: it stops the replication fork from continuing in one direction, but a fork going the other direction is allowed to proceed.

Binding site

Each RTP dimer binds to a binding site 20 bp long. A ''ter'' site on the actual bacterial chromosome consists of two dimer-binding sites "A" and "B", with 3 bp of overlap. The "A" site matches the preference of RTP better and hence has higher affinity. Binding of the "A" site with an RTP dimer changes the shape of the "B" site such that it is easier to bind to another RTP dimer.

Mechanism

Before 2006, it was assumed that RTP simply terminates DNA replication by clamping onto the DNA and physically blocking the

replication fork In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms, acting as the most essential part of biological inheritanc ...

. In 2006, a study found that the contact between RTP and the DNA replication machinery likely also plays a role.

References

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External links

Replication Termination Protein
on Proteopedia DNA-binding proteins