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Structure of 5-hydroxymethylcytosine-specific restriction enzyme, AbaSI, in complex with DNA
, 2014
"... AbaSI, a member of the PvuRts1I-family of modification-dependent restriction endonucleases, cleaves deoxyribonucleic acid (DNA) containing 5-hydroxymethylctosine (5hmC) and glucosylated 5hmC (g5hmC), but not DNA containing unmodified cytosine. AbaSI has been used as a tool for map-ping the genomic l ..."
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AbaSI, a member of the PvuRts1I-family of modification-dependent restriction endonucleases, cleaves deoxyribonucleic acid (DNA) containing 5-hydroxymethylctosine (5hmC) and glucosylated 5hmC (g5hmC), but not DNA containing unmodified cytosine. AbaSI has been used as a tool for map-ping the genomic locations of 5hmC, an important epigenetic modification in the DNA of higher organ-isms. Here we report the crystal structures of AbaSI in the presence and absence of DNA. These struc-tures provide considerable, although incomplete, in-sight into how this enzyme acts. AbaSI appears to be mainly a homodimer in solution, but inter-acts with DNA in our structures as a homotetramer.
Molecular basis for the substrate specificity and catalytic mechanism of thymine-7-hydroxylase in fungi
, 2015
"... TET proteins play a vital role in active DNA demethy-lation in mammals and thus have important functions in many essential cellular processes. The chem-istry for the conversion of 5mC to 5hmC, 5fC and 5caC catalysed by TET proteins is similar to that of T to 5hmU, 5fU and 5caU catalysed by thymine-7 ..."
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TET proteins play a vital role in active DNA demethy-lation in mammals and thus have important functions in many essential cellular processes. The chem-istry for the conversion of 5mC to 5hmC, 5fC and 5caC catalysed by TET proteins is similar to that of T to 5hmU, 5fU and 5caU catalysed by thymine-7-hydroxylase (T7H) in the nucleotide anabolism in fungi. Here, we report the crystal structures and bio-chemical properties of Neurospora crassa T7H. T7H can bind the substrates only in the presence of co-substrate, and binding of different substrates does not induce notable conformational changes. T7H ex-hibits comparable binding affinity for T and 5hmU, but 3-fold lower affinity for 5fU. Residues Phe292, Tyr217 and Arg190 play critical roles in substrate binding and catalysis, and the interactions of the C5 modification group of substrates with the cosub-strate and enzyme contribute to the slightly varied binding affinity and activity towards different sub-strates. After the catalysis, the products are released and new cosubstrate and substrate are reloaded to conduct the next oxidation reaction. Our data reveal the molecular basis for substrate specificity and cat-alytic mechanism of T7H and provide new insights into the molecular mechanism of substrate recogni-tion and catalysis of TET proteins.
Structure of the N-glycosidase MilB in complex with
, 2014
"... hydroxymethyl CMP reveals its Arg23 specifically recognizes the substrate and controls its entry ..."
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hydroxymethyl CMP reveals its Arg23 specifically recognizes the substrate and controls its entry
recognizes the substrate
, 2014
"... Structure of the N-glycosidase MilB in complex with hydroxymethyl CMP reveals its Arg23 specifically ..."
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Structure of the N-glycosidase MilB in complex with hydroxymethyl CMP reveals its Arg23 specifically
