Oxidative DNA damage is instrumental in hyperreplication stress-induced inviability of Escherichia coli

TY - JOUR

T1 - Oxidative DNA damage is instrumental in hyperreplication stress-induced inviability of Escherichia coli

AU - Charbon, Godefroid

AU - Bjørn, Louise

AU - Mendoza-Chamizo, Belén

AU - Frimodt-Møller, Jakob

AU - Løbner-Olesen, Anders

N1 - © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

PY - 2014/12/1

Y1 - 2014/12/1

N2 - In Escherichia coli, an increase in the ATP bound form of the DnaA initiator protein results in hyperinitiation and inviability. Here, we show that such replication stress is tolerated during anaerobic growth. In hyperinitiating cells, a shift from anaerobic to aerobic growth resulted in appearance of fragmented chromosomes and a decrease in terminus concentration, leading to a dramatic increase in ori/ter ratio and cessation of cell growth. Aerobic viability was restored by reducing the level of reactive oxygen species (ROS) or by deleting mutM (Fpg glycosylase). The double-strand breaks observed in hyperinitiating cells therefore results from replication forks encountering single-stranded DNA lesions generated while removing oxidized bases, primarily 8-oxoG, from the DNA. We conclude that there is a delicate balance between chromosome replication and ROS inflicted DNA damage so the number of replication forks can only increase when ROS formation is reduced or when the pertinent repair is compromised.

AB - In Escherichia coli, an increase in the ATP bound form of the DnaA initiator protein results in hyperinitiation and inviability. Here, we show that such replication stress is tolerated during anaerobic growth. In hyperinitiating cells, a shift from anaerobic to aerobic growth resulted in appearance of fragmented chromosomes and a decrease in terminus concentration, leading to a dramatic increase in ori/ter ratio and cessation of cell growth. Aerobic viability was restored by reducing the level of reactive oxygen species (ROS) or by deleting mutM (Fpg glycosylase). The double-strand breaks observed in hyperinitiating cells therefore results from replication forks encountering single-stranded DNA lesions generated while removing oxidized bases, primarily 8-oxoG, from the DNA. We conclude that there is a delicate balance between chromosome replication and ROS inflicted DNA damage so the number of replication forks can only increase when ROS formation is reduced or when the pertinent repair is compromised.

KW - Adenosine Triphosphatases

KW - Aerobiosis

KW - Anaerobiosis

KW - Chromosomes, Bacterial

KW - DNA Breaks, Double-Stranded

KW - DNA Damage

KW - DNA Repair

KW - DNA Replication

KW - DNA, Bacterial

KW - Escherichia coli

KW - Escherichia coli Proteins

KW - Microbial Viability

KW - Mutation

KW - Oxidative Stress

U2 - 10.1093/nar/gku1149

DO - 10.1093/nar/gku1149

M3 - Journal article

C2 - 25389264

SN - 0305-1048

VL - 42

SP - 13228

EP - 13241

JO - Nucleic Acids Research

JF - Nucleic Acids Research

IS - 21

ER -