FIG. 1.

HPLC chromatograms of tRNA hydrolysates from the wild-type (A) and iscS51 mutant (B) strains. The nucleosides were monitored at 295 nm to maximize the detection of all thiolated nucleosides. mnm⁵s²U, cmnm⁵s²U, s²C, ms²io⁶A, s⁴U, ms²i⁶A, pseudouridine (Ψ), and N-6-isopentenyladenosine (i⁶A) were identified by comparing UV spectra with published spectra (13). For s²C, the molecular weight of the protonated form was determined by mass spectrometry (Jäger et al., unpublished data). AU, absorbance units.