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Covalent association of the traI gene product of plasmid RP4 with the 5'-terminal nucleotide at the relaxation nick site
- Source :
- Journal of Biological Chemistry. 265:10637-10644
- Publication Year :
- 1990
- Publisher :
- Elsevier BV, 1990.
-
Abstract
- Formation of relaxosomes is the first step in the initiation of transfer DNA replication during bacterial conjugation. This nucleoprotein complex contains all components capable of introducing a site- and strand-specific nick at a cognate transfer origin (oriT) on supercoiled plasmid DNA, thus providing the substrate for generation of the strand to be transferred. Characterization of the terminal nucleotides at the oriT nick site revealed that relaxation occurs by hydrolysis of a single phosphodiester bond between a 2'-deoxyguanosyl and a 2'-deoxycytidyl residue. The relaxation nick site and a 19-base pair invert repeat sequence that is recognized by asymmetric binding of the RP4 TraJ protein are interspaced by 8 base pairs. The nicking reaction results in covalent attachment of the RP4 TraI protein to the 5'-terminal 2'-deoxycytidyl residue of the cleaved strand. The arrangement of the TraJ binding site and the relaxation nick site on the same side of the DNA double helix suggests that protein-protein interactions between TraJ and TraI are a prerequisite for oriT specific nicking. In accordance with the current model of transfer DNA replication, the 3' end remains accessible for primer extension by DNA polymerase I, enabling replacement strand synthesis in the donor cell by a rolling circle-type mechanism.
- Subjects :
- DNA Replication
DNA, Bacterial
Models, Molecular
Base pair
Stereochemistry
Molecular Sequence Data
Restriction Mapping
Biology
Biochemistry
chemistry.chemical_compound
Bacterial Proteins
Escherichia coli
Cloning, Molecular
Binding site
Molecular Biology
Binding Sites
Base Sequence
Bacterial conjugation
Cell Biology
Nicking enzyme
Relaxosome
chemistry
Genes, Bacterial
Replication Initiation
Conjugation, Genetic
biology.protein
Nucleic Acid Conformation
DNA polymerase I
DNA
Plasmids
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 265
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....8d17de265020a4d142d1b89697012086