Crystal Structure of the tRNA Processing Enzyme RNase PH fromAquifex aeolicus

Ryohei Ishii, Osamu Nureki, Shigeyuki Yokoyama
2003 Journal of Biological Chemistry  
RNase PH is one of the exoribonucleases that catalyze the 3 end processing of tRNA in bacteria. RNase PH removes nucleotides following the CCA sequence of tRNA precursors by phosphorolysis and generates mature tRNAs with amino acid acceptor activity. In this study, we determined the crystal structure of Aquifex aeolicus RNase PH bound with a phosphate, a co-substrate, in the active site at 2.3-Å resolution. RNase PH has the typical ␣/␤ fold, which forms a hexameric ring structure as a trimer of
more » ... ture as a trimer of dimers. This ring structure resembles that of the polynucleotide phosphorylase core domain homotrimer, another phosphorolytic exoribonuclease. Four amino acid residues, Arg-86, Gly-124, Thr-125, and Arg-126, of RNase PH are involved in the phosphate-binding site. Mutational analyses of these residues showed their importance in the phosphorolysis reaction. A docking model with the tRNA acceptor stem suggests how RNase PH accommodates substrate RNAs.
doi:10.1074/jbc.m300639200 pmid:12746447 fatcat:tn5jb7bpmbhgfomndktcxibwr4