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The structural basis for recognition of J-base containing DNA by a novel DNA-binding domain in JBP1
Structural highlights
FunctionJBP1_LEITA Dioxygenase that catalyzes the first step of DNA base J (beta-d-glucosyl-HOMedU) biosynthesis by converting thymine to 5-hydroxymethyluracil (HOMedU). DNA base J is a hypermodified thymidine residue found in the genome of kinetoplastid parasites, which is localized primarily to repetitive DNA, namely the telomeres, and is implicated in the regulation of antigenic variation. Also specifically binds to base J-containing DNA (J-DNA). Involved in propagation and maintenance of DNA base J synthesis initiated by JBP2 by specifically binding already synthesized DNA base J and propagating J synthesis. Thymine dioxygenase activity and J-DNA-binding are independent functions.[1] Publication Abstract from PubMedThe J-binding protein 1 (JBP1) is essential for biosynthesis and maintenance of DNA base-J (beta-d-glucosyl-hydroxymethyluracil). Base-J and JBP1 are confined to some pathogenic protozoa and are absent from higher eukaryotes, prokaryotes and viruses. We show that JBP1 recognizes J-containing DNA (J-DNA) through a 160-residue domain, DB-JBP1, with 10 000-fold preference over normal DNA. The crystal structure of DB-JBP1 revealed a helix-turn-helix variant fold, a 'helical bouquet' with a 'ribbon' helix encompassing the amino acids responsible for DNA binding. Mutation of a single residue (Asp525) in the ribbon helix abrogates specificity toward J-DNA. The same mutation renders JBP1 unable to rescue the targeted deletion of endogenous JBP1 genes in Leishmania and changes its distribution in the nucleus. Based on mutational analysis and hydrogen/deuterium-exchange mass-spectrometry data, a model of JBP1 bound to J-DNA was constructed and validated by small-angle X-ray scattering data. Our results open new possibilities for targeted prevention of J-DNA recognition as a therapeutic intervention for parasitic diseases. The structural basis for recognition of base J containing DNA by a novel DNA binding domain in JBP1.,Heidebrecht T, Christodoulou E, Chalmers MJ, Jan S, Ter Riet B, Grover RK, Joosten RP, Littler D, van Luenen H, Griffin PR, Wentworth P Jr, Borst P, Perrakis A Nucleic Acids Res. 2011 Mar 16. PMID:21415010[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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