Department of Applied Biological Chemistry, University of Tokyo
○Min Ze Jia Jun Otsuka Woo Cheol Lee Koji Nagata Masaru Tanokura

The eukaryotic rRNA processing factor Dim2p is required for the cleavage of rRNA precursors at processing sites A₂ to generate the pre-20S rRNA. Its homologs are distributed from archaea to metazoa. In this study, we have solved the crystal structure of PH-Dim2p (Dim2p from Pyrococcus horikoshii OT3) at 2.0-Å resolution. The PH-Dim2p molecule contains two KH domains, KH-1 and KH-2, which have dissimilar molecular surfaces in terms of electrostatic potentials. Binding assays have shown that PH-Dim2p shows no sequence preference in target rRNA molecules and that only KH-1 binds 16S rRNA while KH-2 does not. Based on the crystal structure of PH-Dim2p and the binding assay data, we have constructed a putative model of the PH-Dim2p and ribosomal RNA complex.