PRELIMINARY-X-RAY DIFFRACTION STUDIES OF AN RNA PSEUDOKNOT THAT INHIBITS HIV-1 REVERSE-TRANSCRIPTASE

Crystals of a 26-nucleotide pseudoknot RNA, PK26, have been grown. The RNA was produced using phosphoramidite chemistry and was purified by denaturing polyacrylamide electrophoresis. The crystallization was rob ust with respect to changes in the number of nucleotides and to the sa lt used as precipitant. The crystals belong to space group P4(1)22 or P4(3)22 with unit-cell dimensions a=b=61.6, c=98.9 Angstrom. The best crystals diffract X-rays to 2.9 Angstrom. Three different sequences in corporating a single 5-bromo-deoxyuridine or 5-bromo-uridine nucleotid e were also crystallized. True of these derivatives are being used to determine the structure by multiple isomorphous replacement.