Human telomere DNA (Htelo) and telomeric repeat-containing RNA (TERRA) are integral telomere components containing the short DNA repeats d(TTAGGG) and RNA repeats r(UUAGGG), respectively. Htelo and TERRA form G-quadruplexes, but the biological significance of their G-quadruplex formation in telomeres is unknown. Compounds that selectively bind G-quadruplex DNA and RNA are useful for understanding the functions of each G-quadruplex. Here we report that engineered Arg-Gly-Gly repeat (RGG) domains of translocated in liposarcoma containing only Phe (RGGF) and Tyr (RGGY) specifically bind and stabilize the G-quadruplexes of Htelo and TERRA, respectively. Moreover, RGGF inhibits trimethylation of both histone H4 at lysine 20 and histone H3 at lysine 9 at telomeres, while RGGY inhibits only H3 trimethylation in living cells. These findings indicate that G-quadruplexes of Htelo and TERRA have distinct functions in telomere histone methylation.

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A New Non-Azole Inhibitor of ABA 8'-Hydroxylase: Effect of the Hydroxyl Group Substituted for Geminal Methyl Groups in the Six-Membered Ring. -Design and synthesis of inhibitor (I) are described. The (+)-enantiomer competitively inhibits 8'-hydroxylation of abscisic acid by recombinant CYP707A3. -(ARAKI, Y.; MIYAWAKI, A.; MIYASHITA, T.; MIZUTANI, M.; HIRAI, N.; TODOROKI*, Y.; Bioorg.