The positive and negative regulation of Tn10 transposition by IHF is mediated by structurally asymmetric transposon arms
AUTOR(ES)
Sewitz, Sven
FONTE
Oxford University Press
RESUMO
The Tn10 transpososome has symmetrical components on either side: there are two transposon ends each of which has binding sites for a monomer of transposase and an IHF heterodimer. The DNA bending activity of IHF stimulates assembly of an intermediate with tightly folded transposon ends in which transposase has additional ‘subterminal’ DNA contacts, located distal to the IHF site. These subterminal contacts are required to activate later steps in the reaction. Quantitative hydroxyl radical footprinting and gel retardation unfolding experiments show that the transpososome is fundamentally asymmetric, despite having identical components on either side. Major differences between the transposon ends define α and β sides of the complex. IHF can dissociate from the transposon arm on the β side of the complex in the absence of metal ion. However, IHF is locked onto the α side of the complex, probably by the subterminal transposase contacts, until released by a metal ion-dependent conformational change. Later in the reaction, IHF inhibits target interactions. Using a very short transposon arm, target interactions are demonstrated at a saturating IHF concentration. This suggests that inhibition of target interactions is due to steric hindrance of the target binding site by a single IHF-folded transposon arm.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=219475Documentos Relacionados
- Regulating Tn10 and Is10 Transposition
- Resistance to various tetracyclines mediated by transposon Tn10 in Escherichia coli K-12.
- Excision of Tn10 from the donor site during transposition occurs by flush double-strand cleavages at the transposon termini.
- IS10/Tn10 transposition efficiently accommodates diverse transposon end configurations.
- Determinants for hairpin formation in Tn10 transposition