Related Experiment Video
Updated: Aug 29, 2026

Genetic Modification of Cyanobacteria by Conjugation Using the CyanoGate Modular Cloning Toolkit
Published on: October 31, 2019
LexA-binding sequences in Gram-positive and cyanobacteria are closely related
G Mazón1, J M Lucena, S Campoy
1Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain.
Abstract:
The lexA gene of the cyanobacterium Anabaena sp. strain PCC7120 has been cloned by PCR amplification with primers designed after TBLASTN analysis of its genome sequence using the Escherichia coli LexA sequence as a probe. After over-expression in E. coli and subsequent purification, footprinting experiments demonstrated that the Anabaena LexA protein binds to the sequence TAGTACTAATGTTCTA, which is found upstream of its own coding gene. Directed mutagenesis and sequence comparison of promoters of other Anabaena genes, as well as those of several cyanobacteria, allowed us to define the motif RGTACNNNDGTWCB as the LexA box in this bacterial phylum. Substitution of a single nucleotide in this motif present in the Anabena lexA promoter is sufficient to enable it to bind the Bacillus subtilis LexA protein. These data indicate that Cyanobacteria and Gram-positive bacteria are phylogenetically closely related.
Related Concept Videos
Prokaryotic Transcriptional Activators and Repressors
Transcription of prokaryotic...
Cis-regulatory Sequences
Cooperative Binding of Transcription Regulators
Gene Regulation in Microbial Communities: Quorum Sensing
Bacterial Phylum Cyanobacteria
Bacterial RNA Polymerase
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...

