5n8o

Structural highlights

Function

TRAI1_ECOLI Conjugative DNA transfer (CDT) is the unidirectional transfer of ssDNA plasmid from a donor to a recipient cell. It is the central mechanism by which antibiotic resistance and virulence factors are propagated in bacterial populations. Part of the relaxosome, which facilitates a site- and strand-specific cut in the origin of transfer by TraI, at the nic site. Relaxosome formation requires binding of IHF and TraY to the oriT region, which then faciliates binding of TraI relaxase. TraI forms a covalent 5'-phosphotyrosine intermediate linkage to the ssDNA. The transesterified T-strand moves from the donor cell to the recipient cell in a 5'to 3' direction, with the DNA helicase activity of TraI unwinding the DNA. DNA transfer occurs via the conjugative pore (transferosome) an intercellular junction mediated by a type IV secretion system, with TraD providing the means to link the relaxosome to the conjugative pore. The relaxase completes DNA transfer by reversing the covalent phosphotyrosine linkage and releasing the T-strand.^{[1] [2] [3] [4] [5]} TraI has also been identified as DNA helicase I. DNA. helicase I is a potent, highly processive DNA-dependent ATPase, able to unwind about 1.1 kb dsDNA per second in a 5' to 3' manner.^{[6] [7] [8] [9] [10]}

See Also

• Helicase 3D structures

References

1. ↑ Street LM, Harley MJ, Stern JC, Larkin C, Williams SL, Miller DL, Dohm JA, Rodgers ME, Schildbach JF. Subdomain organization and catalytic residues of the F factor TraI relaxase domain. Biochim Biophys Acta. 2003 Mar 21;1646(1-2):86-99. PMID:12637015
2. ↑ Abdel-Monem M, Taucher-Scholz G, Klinkert MQ. Identification of Escherichia coli DNA helicase I as the traI gene product of the F sex factor. Proc Natl Acad Sci U S A. 1983 Aug;80(15):4659-63. PMID:6308637
3. ↑ Matson SW, Nelson WC, Morton BS. Characterization of the reaction product of the oriT nicking reaction catalyzed by Escherichia coli DNA helicase I. J Bacteriol. 1993 May;175(9):2599-606. PMID:8386720
4. ↑ Nelson WC, Howard MT, Sherman JA, Matson SW. The traY gene product and integration host factor stimulate Escherichia coli DNA helicase I-catalyzed nicking at the F plasmid oriT. J Biol Chem. 1995 Nov 24;270(47):28374-80. PMID:7499339
5. ↑ Stern JC, Schildbach JF. DNA recognition by F factor TraI36: highly sequence-specific binding of single-stranded DNA. Biochemistry. 2001 Sep 25;40(38):11586-95. PMID:11560509
6. ↑ Street LM, Harley MJ, Stern JC, Larkin C, Williams SL, Miller DL, Dohm JA, Rodgers ME, Schildbach JF. Subdomain organization and catalytic residues of the F factor TraI relaxase domain. Biochim Biophys Acta. 2003 Mar 21;1646(1-2):86-99. PMID:12637015
7. ↑ Abdel-Monem M, Taucher-Scholz G, Klinkert MQ. Identification of Escherichia coli DNA helicase I as the traI gene product of the F sex factor. Proc Natl Acad Sci U S A. 1983 Aug;80(15):4659-63. PMID:6308637
8. ↑ Matson SW, Nelson WC, Morton BS. Characterization of the reaction product of the oriT nicking reaction catalyzed by Escherichia coli DNA helicase I. J Bacteriol. 1993 May;175(9):2599-606. PMID:8386720
9. ↑ Nelson WC, Howard MT, Sherman JA, Matson SW. The traY gene product and integration host factor stimulate Escherichia coli DNA helicase I-catalyzed nicking at the F plasmid oriT. J Biol Chem. 1995 Nov 24;270(47):28374-80. PMID:7499339
10. ↑ Stern JC, Schildbach JF. DNA recognition by F factor TraI36: highly sequence-specific binding of single-stranded DNA. Biochemistry. 2001 Sep 25;40(38):11586-95. PMID:11560509
11. ↑ Ilangovan A, Kay CWM, Roier S, El Mkami H, Salvadori E, Zechner EL, Zanetti G, Waksman G. Cryo-EM Structure of a Relaxase Reveals the Molecular Basis of DNA Unwinding during Bacterial Conjugation. Cell. 2017 May 4;169(4):708-721.e12. doi: 10.1016/j.cell.2017.04.010. Epub 2017, Apr 27. PMID:28457609 doi:http://dx.doi.org/10.1016/j.cell.2017.04.010