A green nonsulfur bacterium, Dehalococcoides ethenogenes, with the LexA binding sequence found in gram-positive...

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Dehalococcoides ethenogenes belongs to the green nonsulfur bacteria division.
• LexA protein regulates gene expression in response to DNA damage.
• Understanding LexA binding in diverse bacteria is crucial for comprehending DNA repair mechanisms.

Purpose of the Study:

• To identify, clone, express, and purify the lexA gene and its protein from Dehalococcoides ethenogenes.
• To investigate the DNA binding specificity of the D. ethenogenes LexA protein.
• To compare the LexA binding site with those found in other bacterial species.

Main Methods:

• TBLASTN search for lexA gene identification.
• Gene cloning, expression, and protein purification.
• Electrophoretic mobility shift assays (EMSA) to determine DNA-protein interactions.

Main Results:

• The D. ethenogenes lexA gene and protein were successfully characterized.
• The D. ethenogenes LexA protein specifically binds to its own promoter and the uvrA promoter, but not the recA promoter.
• The identified LexA binding site sequence is GAACN(4)GTTC, identical to that in gram-positive bacteria.
• Bacillus subtilis DinR protein demonstrated specific binding to the D. ethenogenes LexA operator.

Conclusions:

• Dehalococcoides ethenogenes possesses a LexA binding site conserved in gram-positive bacteria.
• This finding indicates a shared regulatory mechanism for DNA repair across different bacterial phyla.
• This is the first report of such conserved LexA binding in a non-gram-positive bacterium.