Push and pull of base flipping

Article Abstract:

The human uracil-DNA glycosylase (UDG) removes uracil residues from DNA by pushing the target uracil base out of the DNA helix and pulling it into its active site where the uracil is excised. The crystal structure of the enzyme linked to a ten-base-pair DNA duplex with a U-G mismatch reveals that UDG uses some amino acids to compress the DNA backbone flanking the uracil residue. The uracil, deoxyribose and 5' phosphate are pulled out into the major groove. The interaction of the uracil with certain amino acid of UDG stabilize it, and it is subsequently excised.

Analysis, Reports, Observations, Enzymes, Molecular structure

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OGG1 initiates age-dependent CAG trinucleotide expansion in somatic cells

Article Abstract:

The age-dependent somatic mutation associated with Huntington's disease has occurred in the process of removing oxidized base lesions and it is dependent on a single base excision repair enzyme, 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1). The results have supported a 'toxic oxidation' model in which OGG1 has initiated an escalating oxidation-excision cycle leading to progressive age-dependent expansion.

Science & research, Causes of, Physiological aspects, Genetic aspects, Huntington's chorea, Huntington's disease, Somatic cells

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The lyase activity of the DNA repair protein beta-polymerase protects from DNA-damage-induced cytotoxicity

Article Abstract:

A new study seeks to show that methylating agent hypersensitivity in beta-polymerase null cells is reversed only by the drP lyase activity of beta-polymerase.

Cell death, DNA polymerases

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