Poster abstracts

Poster number 54 submitted by Kumudie Jayalath

Pseudouridylation enzyme RsuA influence 30S ribosome assembly

Kumudie Jayalath (Chemistry & Biochemistry, Kent State University), Sanjaya Abeysirigunawardena (Chemistry & Biochemistry, Kent State University)

Abstract:
The ribosome is responsible for protein biosynthesis in all living organisms. Bacterial ribosome biogenesis is a complex process that requires synchronization of various cellular events including ribosomal RNA (rRNA) transcription, ribosome assembly, RNA processing and post-transcriptional modification of rRNA. Ribosomal RNA nucleotide modifications and their respective modification enzymes can modulate rRNA folding and ribosome assembly. The only pseudouridine modification found in E. coli 16S ribosomal RNA is located at position 516 of 16S helix 18 which forms the central pseudoknot of the 30S ribosomal subunit. Our circular dichroism spectroscopic data suggest that the helix 18 model RNA undergoes Mg2+-dependent structural changes only in the presence of the pseudouridine modification at position 516. A FRET-based RsuA binding assay developed in our lab shows thermodynamic anti-cooperativity between ribosomal protein S4 and RsuA that catalyzes pseudouridylation of U516. Our data suggest that the RsuA enzyme binds preferably to nonpseudoknoted (extended) helix 18.

Keywords: Pseudouridine, Ribosome assembly