Poster abstracts

Poster number 73 submitted by Reuben Kern

Potential Functional Roles of Self-cleaving Ribozymes in Oryza sativa (Rice)

Reuben G. Kern (Department of Biochemistry and Molecular Biology, Pennsylvania State University), Lauren N. McKinley (Department of Chemistry, Pennsylvania State University), Sarah M. Assmann (Department of Biology, Pennsylvania State University), Philip C. Bevilacqua (Department of Chemistry, Department of Biochemistry and Molecular Biology, Pennsylvania State University)

Abstract:
Twister ribozymes are a class of small self-cleaving RNA enzymes that fold into a complex tertiary structure and self-cleave their sugar-phosphate backbone at a specific site. They have been found in a wide range of species, including bacteria, plants, fungi, and vertebrates, and their structure is highly conserved, suggesting an important in vivo function.1 Despite their abundance in nature, the biological functions of twister ribozymes are generally not understood. A first step in determining twister ribozyme biological function is to characterize their abundance and activity in vivo. Eight different twister ribozymes have been reported in the staple crop Oryza sativa,1 and three more have been found by our lab. Rice is responsible for feeding over half the world’s population, and as such is an important system to study twister ribozyme function in vivo. Using published rice RNA-seq datasets as well as qRT-PCR, we have found that all ribozymes expressed in rice self-cleave. Interestingly, there is a divergence in the abundance of the upstream and downstream cleavage fragments following self-cleavage, suggesting that the self-cleavage fragments are independently regulated. In three of the six expressed transcripts, the upstream fragment is abundant while the downstream fragment is essentially absent and presumably degraded, suggesting the presence of a novel protective element at the nascent 3’ end of the ribozyme-upstream fragment. Such a mechanism could regulate the half-life of the upstream fragment independently of canonical polyadenylated transcript regulation.

References:
Roth, A., Weinberg, Z., Chen, A.G.Y., Kim, P.B., Ames, T.D., Breaker, R.R. (2014). Nature Chemical Biology 10, 56–60.

Keywords: Ribozymes, self-cleavage activity, Oryza sativa