The ultimate goal of this project is to provide insight into the functioning of cellular machines composed of RNA and protein subunits. As a model system, we are studying the introns of the yeast mitochondrial cytochrome b pre-mRNA and the proteins that assist in their splicing. In these simple systems, the RNA components contain the active site for the splicing reaction while the protein components enhance the rate of splicing by holding the RNA in its active conformation. As a first step toward understanding the functioning of this system, we have determined the crystal structure of the bI3 maturase, an intron-encoded protein that facilitates splicing of the intron that encodes it. This crystal structure revealed a conserved nucleic acid binding surface with other members of the LAGLIDADG endonuclease family. Furthermore it revealed how this protein has been inactivated as a functioning DNA endonuclease while maintaining the core structure. Biochemical experiments performed in our collaborator's laboratory showed that this protein binds to the folded self-splicing RNA intron in a peripheral region distant from the splicing active site. Thus, the protein acts at a distance to facilitate folding of the self-splicing RNA. The protein also was shown to bind to the minor groove of the RNA versus typical binding of the LAGLIDADG endonucleases to the major groove of DNA substrates. This suggests that the protein is not changed structurally from DNA-binding homologues, but instead takes advantage of the RNA's wider and more accessible minor groove.
| Harris, Gregory S; Lust, Robert M; Katwa, Laxmansa C et al. (2010) Urotensin II alters vascular reactivity in animals subjected to volume overload. Peptides 31:2075-82 |
| Hazarika, Surovi; Van Scott, Michael R; Lust, Robert M et al. (2010) Pulmonary allergic reactions impair systemic vascular relaxation in ragweed sensitive mice. Vascul Pharmacol 53:258-63 |
| Longo, Antonella; Leonard, Christopher W; Bassi, Gurminder S et al. (2005) Evolution from DNA to RNA recognition by the bI3 LAGLIDADG maturase. Nat Struct Mol Biol 12:779-87 |
