Telomeric localization of the modified DNA base J in the genome of the protozoan parasite Leishmania.
Base J or beta-d-glucosylhydroxymethyluracil is a DNA modification replacing a fraction of thymine in the nuclear DNA of kinetoplastid parasites and of Euglena. J is located in the telomeric sequences of Trypanosoma brucei and in other simple repeat DNA sequences. In addition, J was found in the inactive variant surface glycoprotein (VSG) expression sites, but not in the active expression site of T. brucei, suggesting that J could play a role in transcription silencing in T. brucei. We have now looked at the distribution of J in the genomes of other kinetoplastid parasites. First, we analyzed the DNA sequences immunoprecipitated with a J-antiserum in Leishmania major Friedlin. Second, we investigated the co-migration of J- and telomeric repeat-containing DNA sequences of various kinetoplastids using J-immunoblots and Southern blots of fragmented DNA. We find only approximately 1% of J outside the telomeric repeat sequences of Leishmania sp. and Crithidia fasciculata, in contrast to the substantial fraction of non-telomeric J found in T. brucei, Trypanosoma equiperdum and Trypanoplasma borreli. Our results suggest that J is a telomeric base modification, recruited for other (unknown) functions in some kinetoplastids and Euglena.
Genest
Paul-André
PA
Division of Molecular Biology and Centre of Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Ter Riet
Bas
B
Cijsouw
Tony
T
van Luenen
Henri G A M
HG
Borst
Piet
P
D000818:Animals; D002847:Chromatography, Agarose; D016831:Crithidia fasciculata / Q000235:genetics; D016054:DNA, Protozoan / Q000737:chemistry; D018503:Genome, Protozoan; D005960:Glucosides / Q000032:analysis*; D015151:Immunoblotting; D047468:Immunoprecipitation; D007891:Leishmania / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D016615:Telomere / Q000737:chemistry*; D014349:Trypanosoma cruzi / Q000235:genetics; D014498:Uracil / Q000031:analogs & derivatives* / Q000032:analysis
D016054:DNA, Protozoan; D005960:Glucosides; C084880:5-((glucopyranosyloxy)methyl)uracil; D014498:Uracil