Staggering in the cleavage pattern of E. coli ABC-excinuclease
E. coli ABC excinuclease is a complex of three proteins encoded by the uvrA, uvrB, and uvrC genes. The enzyme repairs DNA mono and diadducts by the single strand cleavage of DNA eight phosphodiester bond 5' and four or five phosphodiester bonds 3' to a DNA lesion and facilitates the removal of the resulting twelve or thirteen nucleotide fragment. In this study, the authors have investigated the excision pattern for ultraviolet (UV) induced diadducts, i.e. cyclobutane pyrimidine dimers and pyrimidine-pyrimidone (6-4) photoproducts. Terminally (5' or 3') labeled DNA was irradiated with 254nm UV and treated with ABC excinuclease before and after photoreactivation of cyclobutane dimers by E. coli DNA photolyase. In this way, the authors were able to differentiate between the cleavage pattern of pyrimidine dimers and of (6-4) photoproducts. Their results show that certain TT cyclobutane dimers and rare TT (6-4) photoproducts are excised by cleavage seven and, less frequently, six phosphodiester bonds to the 5' side of the DNA lesion in addition to the primary cutting site at the eight 5' phosphodiester bond. The 3' cleavage sites are maintained at the fourth and fifth phosphodiester bonds for the these UV induced lesions. These data indicate that the cleavage pattern of the ABC excinuclease may be dependent upon both the type of DNA lesion as well as it surrounding nucleotide sequence. In addition, the authors analysis shows that (6-4) photoproducts are much better substrates for ABC excinuclease than are pyrimidine dimers.
- Research Organization:
- Univ. of North Carolina, Chapel Hill
- OSTI ID:
- 5120798
- Report Number(s):
- CONF-8606151-; TRN: 86-035037
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DNA
GENETIC RADIATION EFFECTS
NUCLEASES
ENZYME ACTIVITY
CLEAVAGE
DNA ADDUCTS
DNA REPAIR
ESCHERICHIA COLI
GENES
PHOTOREACTIVATION
PYRIMIDINE DIMERS
ULTRAVIOLET RADIATION
ADDUCTS
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CRYSTAL STRUCTURE
ELECTROMAGNETIC RADIATION
ENZYMES
ESTERASES
GENETIC EFFECTS
HYDROLASES
MICROORGANISMS
MICROSTRUCTURE
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PHOSPHODIESTERASES
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
560111* - Radiation Effects on Biochemicals- In Vitro- (-1987)