What Factors Lead to Ribosomal Translation and Heme Synthesis?
Authors:Noelle Cea , Cathy Garcia , Jasmyn Jacinto, Izamar Santamaria
Mentor:Luiza Nogaj, Associate Professor of Biology , Mount St. Mary's College
The tetrapyrrole pathway leads to the production of heme and chlorophylls. The first steps of this pathway compete for substrates with protein synthesis. Both mechanisms rely on charged tRNAGlu as a substrate and glutamyl-tRNA synthetase (GTS) is considered necessary for both pathways. The heme pathway delivers Glu-tRNAGlu to glutamly-tRNA reductase (GTR) while the protein synthesis machinery uses EF-Tu to deliver Glu-tRNAGlu to the ribosome. Even though the interactions between GTS and EF-Tu are well understood, it is not known how GTR competes for the charged tRNA. This study examines the interactions between the first enzymes in the heme pathway and their relationship with EF-Tu. Therefore, it was hypothesized that GTR and EF-Tu compete for Glu-tRNAGlu and for interacting with GTS. It was also hypothesized that all the intermediates in this pathway are channeled without being released into the cellular environment and the proteins in the heme pathway interact with each other and form protein complexes. To test these hypotheses, the first enzymes in the tetrapyrrole pathway along with EF-Tu were cloned, overexpressed, and purified. The native gels show protein-protein interactions between enzymes in the heme pathway while further research will be necessary to establish substrate channeling and competitive interactions between the heme and protein pathways.