ATP hydrolysis during SOS induction in Escherichia coli

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• The SOS response is a global DNA damage response in bacteria.
• RecA and LexA proteins are key regulators of the SOS response.
• Cellular energy status, particularly ATP concentration, may influence DNA repair pathways.

Purpose of the Study:

• To investigate the dynamic changes in cellular ATP concentration during SOS induction in Escherichia coli.
• To determine the role of RecA and LexA proteins in ATP level fluctuations during DNA repair.
• To elucidate the relationship between LexA repressor cleavage and ATP consumption.

Main Methods:

• Studying ATP concentration changes in various Escherichia coli strains with differing RecA and LexA protein levels.
• Utilizing UV irradiation as a trigger for SOS induction.
• Comparing ATP levels in wild-type strains, RecA-deficient mutants, and strains with modified LexA repressors.

Main Results:

• UV irradiation caused a transient twofold increase in ATP concentration in wild-type strains, followed by a decrease.
• Mutants lacking functional RecA protein or with cleavage-resistant LexA did not exhibit the ATP decrease, indicating LexA hydrolysis is responsible.
• Constitutive RecA synthesis or defective LexA binding (LexA(Def)) did not alter the observed ATP dynamics compared to wild-type.

Conclusions:

• LexA repressor hydrolysis during SOS induction is directly linked to ATP consumption in Escherichia coli.
• The observed ATP decrease is a consequence of the energy-dependent cleavage of the LexA repressor.
• Understanding ATP dynamics provides insights into the energetic requirements of bacterial DNA repair mechanisms.