Ribosomes are the universal machines for translating the genetic code into protein. The basic organization and function of ribosomes is preserved in all organisms. Since the major macromolecular constituent of all cells is protein, cells require large numbers of ribosomes, especially during periods of rapid growth.

The major focus of our work are two aspects of ribosome biogenesis. First, we are studying how mature rRNA molecules are formed from the primary precursor transcript in Saccharomyces cerevisiae, a process which requires many nucleolar RNA and protein components. In particular we investigate the structure and function of RNase MRP, an RNA protein particle which cleaves the precursor rRNA. The RNA subunit of RNase MRP has many similarities with the RNA subunit of RNase P, an enzyme involved in processing of precursor tRNA. In addition the two RNA containing enzymes share eight of their nine protein subunits. We are pursuing comparative studies of these two RNA-protein enzymes to understand structure and function of the class of processing enzymes.

Second, we investigate transcription and translation regulation of ribosomal protein genes in bacteria. Encoded by the third gene of the eleven gene S10 operon in Escherichia coli, protein L4 is both a regulatory protein and a ribosomal protein. Recently, genetic studies in our lab and crystallography by other groups have pinpointed several sites in L4 for RNA protein interaction that are key determinants in regulation of the S10 operon, assembly of ribosomes and possibly ribosome function. Current work focuses on dissecting the role of the different domains of L4 and the evolution of the regulatory mechanisms for regulation of ribosomal protein synthesis.