Light absorbed by colored intermediates of chlorophyll biosynthesis is not utilized in photosynthesis; instead, it is transferred to molecular oxygen, generating singlet oxygen ((1)O(2)). As there is no enzymatic detoxification mechanism available in plants to destroy (1)O(2), its generation should be minimized. We manipulated the concentration of a major chlorophyll biosynthetic intermediate i...

We describe an assay for 5-aminolevulinic acid dehydratase (EC4.2.1.24) activity. Radioactive [14Cjporphobilinogen, formed by action of this enzyme on [14CJo-aminolevulinic acid, is purified by passage through an ion-exchange chromatographic column before measurement with a liquid scintillation counter. The radioactive substance in the final solution was identified as solely [14C]porphobilinoge...

We investigated systematically the effects of Tet-induced oxidation products of 5-methylcytosine on Dnmt1- and DNMT3a-mediated cytosine methylation in synthetic duplex DNA. We found that the replacement of 5-methylcytosine at a CpG site with a 5-hydroxymethylcytosine, 5-formylcytosine, 5-carboxylcytosine or 5-hydroxymethyluracil resulted in altered methylation of cytosine at both the opposite a...

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Nucleotide variants, especially those related to epigenetic functions, provide critical regulatory information beyond simple genomic sequence, and they define cell status in higher organisms. 5-Methylcytosine, which is found in DNA, was until recently the only nucleotide variant studied in terms of epigenetics in eukaryotes. However, 5-methylcytosine has turned out to be just one component of a...

Cytosine can undergo modifications, forming 5-methylcytosine (5-mC) and its oxidized products 5-hydroxymethylcytosine (5-hmC), 5-formylcytosine (5-fC) and 5-carboxylcytosine (5-caC). Despite their importance as epigenetic markers and as central players in cellular processes, it is not well understood how these modifications influence physical properties of DNA and chromatin. Here we report a co...