Integration site selection by the Bacteroides conjugative transposon CTnBST
Bo Song1, Nadja B Shoemaker, Jeffrey F Gardner
1Department of Microbiology, 601 S. Goodwin Ave., Rm B103, University of Illinois, Urbana, IL 61801, USA. bosong2@uiuc.edu
Journal of Bacteriology
|July 10, 2007
Summary
A new Bacteroides conjugative transposon (CTn), CTnBST, shows unique integration site specificity. Its integrase, IntBST, differs from other tyrosine recombinases, requiring specific amino acids for integration and showing altered sequence homology needs.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Conjugative transposons (CTns) are mobile genetic elements mediating horizontal gene transfer.
- Bacteroides CTns, like CTnDOT, and enterococcal CTn Tn916 are well-studied.
- Site-specific integration is a key feature of many CTns, mediated by integrases.
Purpose of the Study:
- To characterize the integration mechanism of a newly discovered Bacteroides conjugative transposon, CTnBST.
- To compare the site specificity and integrase function of CTnBST with other known CTns.
- To elucidate the sequence requirements for CTnBST integration.
Main Methods:
- Site-directed mutagenesis of the CTnBST integrase (IntBST) and analysis of integration frequency.
- Determination of DNA sequence requirements for CTnBST integration at preferred and secondary sites.
- Comparative analysis of IntBST with other tyrosine recombinases.
Main Results:
- CTnBST exhibits higher site specificity compared to CTnDOT and Tn916.
- IntBST, a tyrosine recombinase family member, shows altered catalytic site requirements, with specific amino acid changes drastically reducing integration.
- CTnBST integration requires homology at one end of a 7-bp crossover region, unlike other site-specific recombinases requiring homology throughout.
Conclusions:
- CTnBST represents a novel type of conjugative transposon with distinct integration properties.
- The IntBST integrase possesses unique catalytic features within the tyrosine recombinase family.
- CTnBST integration mechanism offers insights into the evolution and diversity of mobile genetic elements.
More Related Videos
Related Concept Videos
01:19Mechanism of Conjugation
Bacterial conjugation is a mechanism of horizontal gene transfer that enables the exchange of genetic material between bacterial cells through direct contact. This process is facilitated by a donor cell carrying a conjugative plasmid, which encodes genes necessary for pilus formation, DNA replication, and transfer. The conjugative plasmid plays a central role in initiating and executing the transfer of genetic material.The tra region of the conjugative plasmid encodes proteins responsible for...
01:19Conjugation
Conjugation is a form of horizontal gene transfer that primarily occurs in bacteria and some archaea, promoting genetic diversity and adaptation. Bacteria can acquire resistance genes through conjugative plasmids, allowing them to survive antibiotic treatments that would otherwise be lethal. This process involves direct contact between cells through specialized structures such as the sex pilus and is mediated by conjugative plasmids, including the F (fertility) factor.Conjugation requires...
01:24Transposons
Transposons, or "jumping genes," are small mobile genetic elements (MGEs) that range from 700 to 40,000 base pairs in length. They are found in all organisms and can move within the same chromosome or transfer to different chromosomes. In some cases, transposons can also jump between different host DNA molecules, such as plasmids or viruses, contributing to genetic variability.Barbara McClintock first discovered these mobile genetic elements in the 1940s while studying maize genetics, and she...
00:57Antibiotic Selection
Overview
02:57DNA-only Transposons
DNA-only transposons are called autonomous transposons since they code for the enzyme transposase that is required for the transposition mechanism. Insertion of transposons can alter gene functions in multiple ways. They can mutate the gene, alter gene expression by introducing a novel promoter or insulator sequence, introduce new splice sites, and change the mRNA transcripts produced, or remodel chromatin structure.
The donor site from where the transposon is excised is either degraded or...
The donor site from where the transposon is excised is either degraded or...
02:53Conservative Site-specific Recombination and Phase Variation
Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The recognition sites for Cre recombinase called LoxP...