RNA interference (RNAi) is an evolutionarily conserved
post-transcriptional gene silencing mechanism, which uses
small double-stranded RNAs that target cognate mRNAs in a
sequence-specific manner. Understanding the structure and
function of the RNAi machinery is crucial for developing
tools for gene-function analysis and therapeutic agents for
a variety of human diseases. One of the chief components
of the RNAi machinery is the RNAse III family protein Dicer,
which generates small interfering RNAs (siRNAs) or microRNAs
(miRNAs) from long double stranded RNAs and genome encoded
precursor hairpin miRNAs respectively. Dicer generally has two
RNAse III domains, and in addition has an N-terminal helicase
domain, a PAZ domain, and a dsRNA-binding domain. It is also
known to interact with several other proteins involved in RNAi,
one of which is the dsRBP (dsRNA binding protein) TRBP (TAR RNA
binding protein). A comprehensive study of the relationship
between the structure and function of Dicer is important
to understanding its contribution in the RNAi machinery.
Towards this end we will use biochemical, biophysical, and
genetic assays to functionally characterize Dicer. We will also
determine the crystal structure of Dicer alone and in complex
with RNA substrate and binding partners such as TRBP.
