Crystal structure of T4 endonuclease V: An excision repair enzyme for a pyrimidine dimer

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:134849

Morikawa, K; Ariyoshi, M; Vassylyev, D ^[1]

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1. Protein Engineering Research Institute, Osaka (Japan); and others

Ultraviolet (UV) light induces the formation of pyrimidine dimers, which are the most prevalent DNA lesion. In bacteriophage T4-infected Escherichia coli, T4 endonuclease V (T4 endV), encoded by the denV gene of bacteriophage T4, is responsible for the first step of the excision repair pathway. Although T4 endV is a very small protein, consisting of 138 amino acids, it catalyzes two distinct reactions, at least in vitro: the cleavage of the glycosyl bond of the 5{prime}-pyrimidine of the cis-syn cyclobutane pyrimidine dimer (pyrimidine dimer glycosylase) and the incision of the phosphodiester bond at the resulting abasic site, producing an {alpha},{beta}-unsaturated aldehyde and a 5{prime}-terminal phosphomonoester. This enzyme is also known to cleave the 3{prime}-phosphodiester bond at an abasic site by {beta}-elimination. It has been also suggested from the salt concentration dependence of the catalytic activity in vitro that the excision-repair involves two distinct steps, in terms of the interaction between the enzyme and DNA. Prior to making specific interaction with a pyrimidine dimer, T4 endV can be nonspecifically bound to DNA duplexes by electrostatic forces and slides on them. Once the enzyme has been specifically bound to a pyrimidine dimer, the glycosylation occurs at the 5{prime}-glycosyl bond in the dimer. It still remains obscure whether or not the same enzyme subsequently acts on the scission of the phosphodiester bond. In this report, we describe the three-dimensional (3D) structure of the T4 endV determined at atomic resolution by x-ray crystallography, and discuss the functional implications of the enzyme. The examination of structural features, including atomic resolution crystal structures of three different mutants, allows the identification of residues that participate in the substrate binding and the catalytic reaction of glycosylase.

• Research Organization: New York Academy of Sciences, New York, NY (United States)
• OSTI ID: 134849
• Report Number(s): CONF-9307221--
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
AMINO ACIDS
BACTERIOPHAGES
CATALYSIS
CRYSTAL STRUCTURE
DNA
DNA REPAIR
ENDONUCLEASES
ENZYME ACTIVITY
ESCHERICHIA COLI
GENES
GENETIC RADIATION EFFECTS
MOLECULAR STRUCTURE
MUTATIONS
PROTEINS
PYRIMIDINE DIMERS
SIZE
ULTRAVIOLET RADIATION