beta-D-glucosyl-hydroxymethyluracil, a novel base in African trypanosomes and other Kinetoplastida.
A novel base, beta-D-glucosyl-hydroxymethyluracil or J for short, was recently discovered in DNA of bloodstream form Trypanosoma brucei. The base is predominantly found in the hexameric repeat arrays of chromosome telomeres and in adjacent repetitive sub-telomeric DNA, and it is made by modification of specific thymines in DNA. J is present in inactive telomeric variant surface glycoprotein (VSG) genes, but not in active ones, suggesting a link between the presence of J and repression of the telomeric expression sites for VSG genes. The presence of J in DNA is specific for bloodstream form trypanosomes, as J is absent in insect form (procyclic) T. brucei. In addition to African trypanosomes, J has been found in DNA from other Kinetoplastida that do not undergo antigenic variation, such as Leishmania and Crithidia. The biological function of J remains to be deciphered.
Borst
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The Netherlands Cancer Institute, Division of Molecular Biology, Amsterdam.
van Leeuwen
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D000818:Animals; D004262:DNA Restriction Enzymes / Q000378:metabolism; D016054:DNA, Protozoan / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D017125:Genes, Protozoan; D005960:Glucosides / Q000032:analysis* / Q000096:biosynthesis; D016830:Kinetoplastida / Q000737:chemistry* / Q000235:genetics; D008957:Models, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D014345:Trypanosoma / Q000737:chemistry* / Q000235:genetics; D014346:Trypanosoma brucei brucei / Q000737:chemistry* / Q000235:genetics; D014498:Uracil / Q000031:analogs & derivatives* / Q000032:analysis / Q000096:biosynthesis
D016054:DNA, Protozoan; D005960:Glucosides; C084880:5-((glucopyranosyloxy)methyl)uracil; D014498:Uracil; D004262:DNA Restriction Enzymes