TY - JOUR
T1 - The telomeric GGGTTA repeats of Trypanosoma brucei contain the hypermodified base J in both strands
AU - van Leeuwen, Fred
AU - Wijsman, Eric R.
AU - Kuyl-Yeheskiely, Esther
AU - van der Marel, Gijs A.
AU - van Boom, Jacques H.
AU - Borst, Piet
PY - 1996
Y1 - 1996
N2 - We have previously shown that nuclear DNA of bloodstream form Trypanosoma brucei contains a novel base β-glucosyl-hydroxymethyluracil, called J. Base J is enriched in minichromosome fractions but not in the minichromosome internal repeats, suggesting the association of J with telomeric DNA. To test whether J is present in the long telomeric (GGGTTA)(n) repeat arrays, which are 2-26 kb in T.brucei, we have purified these arrays both by hybrid selection and by isolating 2-26 kb fragments from DNA digested with multiple restriction enzymes. We find that in purified telomeric repeats ~ 13% of T is replaced by J, compared to 0.8% in total DNA, and we estimate that ~ 50% of the total J is in these repeats. Highly purified complementary strands of the repeats were obtained by alkaline CsCI equilibrium centrifugation, In the (TAACCC)(n) strand 14% of T was replaced by J. In the (GGGTTA)(n) strand ~ 36% of the second T was replaced by J; the first T was not detectably replaced. Modified bases have not been found in telomeric repeats before. How the bulky base J affects telomere function and structure in bloodstream form trypanosomes remains to be determined.
AB - We have previously shown that nuclear DNA of bloodstream form Trypanosoma brucei contains a novel base β-glucosyl-hydroxymethyluracil, called J. Base J is enriched in minichromosome fractions but not in the minichromosome internal repeats, suggesting the association of J with telomeric DNA. To test whether J is present in the long telomeric (GGGTTA)(n) repeat arrays, which are 2-26 kb in T.brucei, we have purified these arrays both by hybrid selection and by isolating 2-26 kb fragments from DNA digested with multiple restriction enzymes. We find that in purified telomeric repeats ~ 13% of T is replaced by J, compared to 0.8% in total DNA, and we estimate that ~ 50% of the total J is in these repeats. Highly purified complementary strands of the repeats were obtained by alkaline CsCI equilibrium centrifugation, In the (TAACCC)(n) strand 14% of T was replaced by J. In the (GGGTTA)(n) strand ~ 36% of the second T was replaced by J; the first T was not detectably replaced. Modified bases have not been found in telomeric repeats before. How the bulky base J affects telomere function and structure in bloodstream form trypanosomes remains to be determined.
UR - https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0029992188&origin=inward
UR - https://www.ncbi.nlm.nih.gov/pubmed/8692684
U2 - https://doi.org/10.1093/nar/24.13.2476
DO - https://doi.org/10.1093/nar/24.13.2476
M3 - Article
C2 - 8692684
SN - 0305-1048
VL - 24
SP - 2476
EP - 2482
JO - Nucleic Acids Research
JF - Nucleic Acids Research
IS - 13
ER -