tRNA binding capacities of ribosomal subunits from the archaebacterium Halobacterium halobium.

tRNA saturation experiments were performed with ribosomal subunits from the extreme halophilic archaebacterium Halobacterium halobium. In the presence of poly(U) the 30S subunit could bind equally well one AcPhe-tRNAPhe, Phe-tRNAPhe, or deacylated tRNAPhe molecule, respectively. Binding experiments with a mixture of two differently labeled tRNA species revealed that all three kinds of tRNA bound to one and the same binding site on the 30S subunit. Poly(U) dependent binding to the 50S subunit was insignificant for AcPhe-tRNA and Phe-tRNA. In the absence of poly(U) both AcPhe-tRNAPhe and Phe-tRNAPhe showed no significant binding to either subunit, whereas the binding of deacylated tRNAPhe could not be clearly determined. These results are in good agreement with those obtained from ribosomal subunits of the eubacterium Escherichia coli.