Search results for "Palindromic sequence"
showing 3 items of 3 documents
Restriction analysis of lambda EMBL3 background recombinants: occurrence of lambda phages carrying a head to tail oriented left arm DNA sequence.
1989
Eight representative recombinant background clones of lambda EMBL3 were analysed using KpnI, BamHI, SalI, EcoRI and HindIII digestion. We found that lambda EMBL3 carries its own left arm in the BamHI cloning site. In the way, recombinant molecules were found to be generated which can grow on Escherichia coli strain NM539. In all cases analysed, the left arm DNA was inserted in a head to tail orientation. Seven clones carried a restored BamHI site at the cos site-BamHI site connection. In the region where the inserted left arm and the right arm were ligated, BamHI cloning produces a large palindromic sequence consisting of two polylinkers. This BamHI site was incompletely cleaved in all case…
Efficient Control of raf Gene Expression by CAP and Two Raf Repressors that Bend DNA in Opposite Directions
1999
The plasmid-borne raf operon of Escherichia coli encodes proteins involved in the uptake and utilisation of the trisaccharide raffinose. The operon is subject to dual regulation; to negative control by the binding of RafR repressor to twin operators, O1 and O2, and to positive control by the cAMP-binding protein, CAP. We have identified the CAP binding site (CBS) as a 22 bp palindromic sequence with incomplete dyad symmetry by deletion analysis, DNasel footprinting and electrophoretic mobility shift assays (EMSA) of CAP-DNA complexes. The CBS is centred 60.5 bp upstream of the transcription start point and partially overlaps O1. In vivo, CAP increases rafA (alpha-galactosidase) gene express…
A natural A/T-rich sequence from the yeast FBP1 gene exists as a cruciform in Escherichia coli cells.
1993
Abstract Palindromic or semipalindromic sequences can adopt cruciform structures in DNA in vitro. It has been demonstrated in some cases that A/T-rich cruciforms exist also in vivo in Escherichia coli. The biological function of those structures is not understood although putative cruciforms have been found in interesting locations on replication origins, operators, or transcriptional termination regions. Here we show by means of the use of structure-dependent nucleases that the 3′ end of the yeast FBP1 gene contains a stable cruciform both in vitro and in E. coli cells and that in both cases, its extrusion depends on the DNA supercoiling state.