The relaxosome is the complex of proteins that facilitates

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria and ...

transfer during

bacterial conjugation Bacterial conjugation is the transfer of genetic material between Bacteria, bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. This takes place through a pilus. It is a parasexual cycle, parasexual mode ...

. The proteins are encoded by the tra operon on a fertility plasmid in the region near the origin of transfer,

oriT Orit () is a Hebrew language feminine given name. Notable people with this given name include: * Orit Gadiesh * Orit Noked * Orit Strook * Orit Wolf * Orit Adato *Orit Rozin Orit Rozin (Hebrew: אורית רוזין) is an Israeli historian. She ...

. The most important of these proteins is relaxase, which is responsible for beginning the conjugation process by cutting at the ''nic'' site via

transesterification Transesterification is the process of exchanging the organic functional group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. Strong acids catalyze the r ...

. This nicking results in a

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

Protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

complex with the relaxosome bound to a single strand of the plasmid DNA and an exposed 3' hydroxyl group. Relaxase also unwinds the plasmid being conjugated with its

helicase Helicases are a class of enzymes that are vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic double helix, separating the two hybridized ...

properties. The relaxosome interacts with integration host factors within the oriT. Other genes that code for relaxosome components include TraH, which stabilizes the relaxosome's structural formation, TraI, which encodes for the relaxase protein, TraJ, which recruits the complex to the oriT site, TraK, which increases the 'nicked' state of the target plasmid, and TraY, which imparts single-stranded DNA character on the oriT site. TraM plays a particularly important role in relaxase interaction by stimulating 'relaxed' DNA formation.

References

* Molecular biology {{Genetics-stub