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An origin of transfer (''oriT'') is a short sequence (up to 500 bp) that is necessary for transfer of the DNA that contains it from a bacterial host to recipient during bacterial conjugation. The ''oriT'' is ''cis''-acting — it is found on the same DNA that is being transferred, and it is transferred along with the DNA. The origin of transfer consists of three functionally defined domains: a nicking domain, a transfer domain, and a termination domain. At the beginning of conjugation of plasmids, a multi-protein complex called the relaxosome assembles around the ''oriT'', with each individual protein binding at specific sites on the ''oriT''. A relaxase (one of the proteins of the relaxosome) nicks the plasmid at the ''nic'' site of the ''oriT'', catalyzing a trans-esterification reaction that transfers the 5' end of the DNA at the ''nic'' site to a tyrosine residue on the relaxase. Relaxase then moves in the 5' to 3' direction on the plasmid, unwinding the DNA in a helicase-like fashion, until it comes a full circle back to the ''oriT'' where the relaxase recognizes a termination domain that causes it to dissociate from the DNA. == References == *Byrd D. R., Matson S. W., 1997. "Nicking by Transesterification: The Reaction Catalysed by a Relaxase." ''Molecular Microbiology'' 25:6, 1011-1022 *Fu Y. H. F., Tsai M. M., Luo Y., Deonier R. C., 1991. "Deletion Analysis of the F Plasmid ori-T Locus." ''Journal of Bacteriology'' 173:3, 1012-1020 *Guasch, et al., 2003. "Recognition and processing of the origin of transfer DNA by conjugative relaxase TrwC." ''Nature Structural Biology'' Vol. 10 No. 12, 1002-1010. *Howard M. T., Nelson W. C., Matson S. W., 1995. "Stepwise Assembly of a Relaxosome at the F Plasmid Origin of Transfer." ''Journal of Biological Chemistry'' 270:47, 28381-28386 *Lanka E., Wilkins B. M., 1995. "DNA Processing Reactions in Bacterial Conjugation." ''Annual Reviews in Biochemistry'' 64:141-169 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「origin of transfer」の詳細全文を読む スポンサード リンク
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