Abstract
DNA from Kinetoplastida contains the unusual modified base beta-D-glucosyl(hydroxymethyl)uracil, called J. Base J is found predominantly in repetitive DNA and correlates with epigenetic silencing of telomeric variant surface glycoprotein genes in Trypanosoma brucei. We have now identified a protein in nuclear extracts of bloodstream stage T.brucei that binds specifically to J-containing duplex DNA. J-specific DNA binding was also observed with extracts from the kinetoplastids Crithidia fasciculata and Leishmania tarentolae. We purified the 90 kDa C.fasciculata J-binding protein 50 000-fold and cloned the corresponding gene from C.fasciculata, T.brucei and L.tarentolae. Recombinant proteins expressed in Escherichia coli demonstrated J-specific DNA binding. The J-binding proteins show 43-63% identity and are unlike any known protein. The discovery of a J-binding protein suggests that J, like methylated cytosine in higher eukaryotes, functions via a protein intermediate.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Cell Nucleus / metabolism
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Crithidia fasciculata / genetics
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DNA, Protozoan / genetics
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DNA, Protozoan / metabolism*
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / metabolism*
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Gene Silencing
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Glucosides / metabolism*
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Kinetoplastida / genetics
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Kinetoplastida / metabolism*
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Leishmania / genetics
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Molecular Sequence Data
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Protozoan Proteins / chemistry
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Protozoan Proteins / genetics
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Protozoan Proteins / metabolism
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Recombinant Proteins / chemistry
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Recombinant Proteins / metabolism
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Sequence Alignment
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Sequence Homology, Amino Acid
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Trypanosoma brucei brucei / genetics
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Uracil / analogs & derivatives*
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Uracil / metabolism
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Variant Surface Glycoproteins, Trypanosoma / genetics*
Substances
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DNA, Protozoan
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DNA-Binding Proteins
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Glucosides
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J-specific DNA-binding protein, protozoa
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Protozoan Proteins
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Recombinant Proteins
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Variant Surface Glycoproteins, Trypanosoma
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5-((glucopyranosyloxy)methyl)uracil
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Uracil
Associated data
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GENBANK/AF182399
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GENBANK/AF182400
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GENBANK/AF182401