PURIFICATION, CRYSTALLIZATION, AND PRELIMINARY-X-RAY DIFFRACTION STUDIES OF TRANSFER-RNA-GUANINE TRANSGLYCOSYLASE FROM ZYMOMONAS-MOBILIS

The tRNA modifying enzyme tRNA-guanine transglycosylase (Tgt) catalyze s the exchange of guanine in the first position of the anticodon with the queuine precursor 7-aminomethyl-7-deazaguanine. Tgt from Zymomonas mobilis has been purified by crystallization and further recrystalliz ed to obtain single crystals suitable for X-ray diffraction studies, C rystals were grown by vapor diffusion/gel crystallization methods usin g PEG 8,000 as precipitant, Macroseeding techniques were employed to p roduce large single crystals, The crystals of Tgt belong to the monocl inic space group C2 with cell constants a = 92.1 Angstrom, b = 65.1 An gstrom, c = 71.9 Angstrom, and beta = 97.5 degrees, and contain one mo lecule per asymmetric unit, A complete diffraction data set from one n ative crystal has been obtained at 1.85 Angstrom resolution. (C) 1996 Wiley-Liss, Inc.