Figure 6.
The dehydrogenase function of SDR5C1 is not required for tRNA methylation or cleavage. Amino acid substitutions were introduced into the cofactor-binding site (S20F), and the active site (K172A) of SDR5C1 and recombinant TRMT10C–SDR5C1 complexes was purified. (A) Relative l-3-hydroxyacyl-CoA dehydrogenase activity of SDR5C1 mutants determined with acetoacetyl-CoA as substrate; mean and standard deviation of triplicates. (B and C) Methyltransferase (upper panels) and mtRNase P (lower panels) activity of recombinant enzyme preparations with mutant SDR5C1 subunits; (B) (mt)tRNAIle with 5′ extension; (C) (mt)tRNALys with 5′ extension.