Vassie Ware, Ph.D.
Professor
Department of Biological Sciences
 
 
 
 
 

Ribosomes are complex ribonucleoprotein particles, required for protein synthesis, and the growth and viability of all cells.  Hence, an evolutionarily conserved structural blueprint for the core components of the ribosome might be expected given the common functional requirement for ribosomes in translation.  Indeed, numerous studies have confirmed that a common folding pattern exists across species for each major ribosomal RNA (rRNA) component, creating a conserved rRNA core structure.  Similarly, several evolutionarily conserved ribosomal protein families also exist, particularly among the primary rRNA binding proteins. Yet, for both rRNA and ribosomal proteins, prominent structural differences often exist between lineages. 

Localized regions of primary and secondary structural variation are particularly evident in the major eukaryotic rRNAs where expansion segments are superimposed on rRNA core structure. Within evolutionarily conserved ribosomal protein families, structural variability often occurs as well between species.  In some instances, conserved proteins may carry additional domains of unknown significance, possibly contributing novel functions for ribosomal proteins in those lineages. When coincident structural variation is displayed within interacting macromolecular ribosomal components, several questions arise about the evolutionary history of the components, including (but not limited to) whether or not the structural changes have co-evolved and if so, whether or not the changes are compensatory in nature to maintain the macromolecular interaction for functional purposes. In general, structural divergence within ribosomal components may ultimately contribute to interspecific differences in ribosome assembly, ribosome function, or the regulation of protein synthesis.

My laboratory is currently studying structural variation in two ribosomal protein families (L23a and L22) and the impact of that variation on ribosome assembly and function as well as the possibility that ribosomal protein variants function in extra-ribosomal pathways in several organisms. Using molecular, genetic, and biochemical approaches, we are focusing on post-transcriptional events in ribosome maturation primarily in the fruit fly, Drosophila melanogaster, including species-specific ribosomal RNA processing mechanisms, developmental and tissue-specific regulation of ribosomal protein L23a and L22 gene expression, and 28S rRNA-ribosomal protein L23a interactions.  Our goals are to determine 1) the recognition signals and biochemical machinery involved in species-specific excision of transcribed spacers from precursor 28S rRNAs in Drosophila melanogaster, and 2) the specific components, interactions, and developmentally-regulated pathways involved in ribosomal assembly in the fly.
 

Representative Publications
Ware, V.C., Renkawitz, R., and Gerbi, S.A. 1985.  rRNA processing:  removal of only nineteen bases at the gap between 28Sa and 28Sb rRNAs in Sciara coprophila. Nucleic Acids Res. 13:3581-3597.

Khanna-Gupta, A. and Ware, V.C.  1989.  Nucleocytoplasmic transport of ribosomes in a eukaryotic system:  is there a facilitated transport mechanism?  Proc. Natl. Acad. Sci. USA. 86:1791-1795.

Dunbar, D.A., Ware, V.C., and Baserga, S.J.  1996.  The U18 snRNA is not essential for pre-rRNA processing in Xenopus laevis.  RNA 2:324-333.

Basile-Borgia, A.E., Dunbar, D.A. and Ware, V.C. (2005) Heterologous rRNA gene expression: internal fragmentation of Sciara coprophila 28S rRNA within microinjected Xenopus laevis oocytes. Insect Molecular Biology, 14, 523-536.

Ross et al. (2007) Functional conservation between structurally diverse ribosomal proteins from Drosophila melanogaster and Saccharomyces cerevisiae: fly L23a can substitute for yeast L25 in ribosome assembly and function. Nucl. Acids Res. 35, 4503-4514.