T4 endonuclease V: Perspectives on catalysis
- Univ. of Texas Medical Branch, Galveston, TX (United States)
Bacteriophage T4 displays enhanced ultraviolet light (UV) resistance over other T-even bacteriophages. This enhanced resistance was initially ascribed to the v gene, now known as denV. The product of the denV gene, endonuclease V, has been shown to be responsible for initiating the removal of pyrimidine dimers from DNA. Initial characterization of purified endonuclease V revealed that the enzyme produces single-strand breaks in DNA at the site of UV-induced pyrimidine dimers, yet shows no activity towards unirradiated or heat-denatured DNA. The enzyme seems almost completely specific for cis-syn cyclobutane pyrimidine dimers, although recently it has been demonstrated to react with trans-syn dimers at approximately 1/100th the rate of the cis-syn dimer. DenV has been cloned and sequenced, allowing for expression of endonuclease V within Escherichia coli. The gene encodes a 138-amino acid protein with a predicted molecular mass of 16 kDa. Extensive biochemical and genetic studies have shown endonuclease V to possess four distinct activities: (1) a salt-dependent scanning or looping mechanism allowing for nontarget double-stranded DNA interactions; (2) a pyrimidine dimer-specific binding activity; (3) a pyrimidine dimer-specific DNA glycosylase activity; and (4) an apurinic/apyrimidinic (AP) lyase activity.
- Research Organization:
- New York Academy of Sciences, New York, NY (United States)
- OSTI ID:
- 134848
- Report Number(s):
- CONF-9307221--; CNN: Grant ES04091
- Country of Publication:
- United States
- Language:
- English
Similar Records
Physical association of pyrimidine dimer DNA glycosylase and apurinic/apyrimidinic DNA endonuclease essential for repair of ultraviolet-damaged DNA
Selective inhibition by methoxyamine of the apurinic/apyrimidinic endonuclease activity associated with pyrimidine dimer-DNA glycosylases from Micrococcus luteus and bacteriophage T4