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JBP1 and JBP2 are two distinct thymidine hydroxylases involved in J biosynthesis in genomic DNA of African trypanosomes
被引:65
作者:
Cliffe, Laura J.
[1
]
Kieft, Rudo
[1
]
Southern, Timothy
[1
]
Birkeland, Shanda R.
[1
]
Marshall, Marion
[1
]
Sweeney, Kate
[1
]
Sabatini, Robert
[1
]
机构:
[1] Univ Georgia, Dept Biochem & Mol Biol, Athens, GA 30602 USA
基金:
美国国家卫生研究院;
关键词:
D-GLUCOSYL-HYDROXYMETHYLURACIL;
J-BINDING PROTEIN;
MODIFIED BASE J;
KINETOPLASTID PROTOZOANS;
SWI2/SNF2-LIKE PROTEIN;
RHODOTORULA-GLUTINIS;
THYMINE HYDROXYLASE;
GENE-EXPRESSION;
BRUCEI;
GLYCOSYLATION;
D O I:
10.1093/nar/gkn1067
中图分类号:
Q5 [生物化学];
Q7 [分子生物学];
学科分类号:
071010 ;
081704 ;
摘要:
Genomic DNA of African trypanosomes contains a hypermodified thymidine residue termed base J (-d-glucosyl-HOMedU). This modified base is localized primarily to repetitive DNA, namely the telomeres, and is implicated in the regulation of antigenic variation. The base is synthesized in a two-step pathway. Initially, a thymidine residue in DNA is hydroxylated by a thymidine hydroxylase (TH). This intermediate (HOMedU) is then glucosylated to form base J. Two proteins involved in J synthesis, JBP1 (J binding protein 1) and JBP2, contain a putative TH domain related to the family of Fe-2/2-oxoglutarate-dependent hydroxylases. We have previously shown that mutations in the TH domain of JBP1 kill its ability to stimulate J synthesis. Here we show that mutation of key residues in the TH domain of JBP2 ablate its ability to induce de novo J synthesis. While the individual JBP1 null and JBP2 null trypanosomes have reduced J levels, the deletion of both JBP1 and JBP2 generates a cell line that completely lacks base J but still contains glucosyl-transferase activity. Reintroduction of JBP2 in the J-null trypanosome stimulates HOMedU formation and site-specific synthesis of base J. We conclude that JBP2 and JBP1 are the TH enzymes involved in J biosynthesis.
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页码:1452 / 1462
页数:11
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