Related Experiment Video
Updated: Aug 9, 2026

Substrate Generation for Endonucleases of CRISPR/Cas Systems
Published on: September 8, 2012
Sequence-directed DNA bending upstream of the streptokinase promoter
Abstract:
A 450-base pair (bp) HinfI restriction fragment from the chromosome of Streptococcus equisimilis H46A contains the early coding region of the streptokinase gene (skc), the skc promoter, and a stretch of DNA 5' to the--35 region of the skc promoter. Two-dimensional polyacrylamide (PA) gel electrophoresis at two different temperatures showed that this fragment migrates anomalously slowly on PA gels, suggesting the existence of a bent DNA conformation. Inspection of the nucleotide sequence confirmed this suggestion by revealing numerous oligomeric dA.dT tracts, some of which are in phase with the helix screw. Computer analysis of the sequence predicted the existence of two bending loci, one of which is located upstream of the skc promoter. In addition to showing DNA bending, the 450-bp HinfI fragment contains multiple 13-bp sequences homologous to the Escherichia coli integration host factor DNA-binding consensus sequence. Insertion of IS1 into a site immediately upstream of the--35 region decreased the expression level of skc in E. coli, suggesting that DNA conformation upstream of the promoter has a role in skc expression.
Related Concept Videos
DNA Topoisomerases
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
Translesion DNA Polymerases
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
Conservative Site-specific Recombination and Phase Variation
The recognition sites for Cre recombinase called LoxP...
Single-Strand DNA Binding Proteins
Bacterial Transcription
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
Restriction Enzymes
The host bacteria protect their own genomic DNA from these enzymes by methylating these sites. Some...

