Poster abstracts
Poster number 48 submitted by Benjamin Warner
A crucial role for the leader-trailer helix and minor role of the antitermination complex in biogenesis of the 30S ribosomal subunit.
Benjamin Warner (Department of Microbiology, Center for RNA Biology), Ralf Bundschuh (Center for RNA Biology, Department of Physics, Department of Chemistry and Biochemistry, Division of Hematology)
Abstract:
Ribosome biogenesis occurs co-transcriptionally and entails rRNA folding, ribosomal protein binding, rRNA processing, and rRNA modification. In most bacteria, rRNAs are transcribed with tRNAs, and the primary transcript contains leader, trailer, and spacer sequences. Transcription of these long operons involves a modified RNAP, called the antitermination complex, which is recruited by cis-acting RNA elements (boxB, boxA, boxC) in the leader and spacer regions of the operon. Flanking sequences of the rRNAs are complementary, forming long helices known as leader-trailer helices. In this work, we interrogate the functional roles of these RNA elements in 30S subunit biogenesis. We find that the leader-trailer helix structure is absolutely critical, although its primary sequence can vary. By contrast, loss of the boxA only modestly impacts 30S production, indicating a minor role for the antitermination complex. The leader helices, termed here hA and hB, are also largely dispensable, consistent with the variable presence of these elements across the Enterobacteriaceae. The fact that the leader-trailer helix is crucial for 30S biogenesis in vivo but unnecessary for efficient reconstitution of the 30S subunits in vitro implies an important difference between the two processes.
Keywords: ribosome biogenesis, RNA structure, precursor RNA