The enzyme exodeoxyribonuclease VII (EC 3.1.11.6, ''Escherichia coli'' exonuclease VII, ''E. coli'' exonuclease VII, endodeoxyribonuclease VII, exodeoxyribonuclease VII) is a
bacterial exonuclease enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
. It is composed of two nonidentical subunits; one large subunit and 4 small ones.
that
catalyses exonucleolytic cleavage in either 5′- to 3′- or 3′- to 5′-direction to yield nucleoside 5′-phosphates. The large subunit also contains an
''N''-terminal OB-fold domain that binds to
nucleic acid
Nucleic acids are large biomolecules that are crucial in all cells and viruses. They are composed of nucleotides, which are the monomer components: a pentose, 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nuclei ...
s.
The widely used
quinolone antibiotic
Quinolone antibiotics constitute a large group of broad-spectrum bacteriocidals that share a bicyclic core structure related to the substance 4-quinolone. They are used in human and veterinary medicine to treat bacterial infections, as wel ...
s induce
DNA damage in bacterial cells by trapping
DNA gyrase (an essential
type II topoisomerase), leading to blocked gyrase cleavage complexes.
Exonuclease VII participates in
repairing such DNA damage by resolving the trapped cleavage complexes.
[
When '']Escherichia coli
''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...
'' bacteria '' recA'' mutants are UV-irradiated, “reckless” DNA degradation occurs that involves exonuclease VII.
References
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Protein families
EC 3.1.11