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Susan Martinis

Department of Biochemistry, College of Liberal Arts and Sciences
Interim Director, Biomedical Sciences and Engineering, Carle Illinois College of Medicine
Interim Vice Chancellor for Research
University of Illinois at Urbana-Champaign

Professor Martinis is an internationally respected scholar in the field of RNA-protein interactions and aminoacyl-tRNA synthetases whose work is most currently supported by the National Institutes of Health, National Science Foundation, and the W.M. Keck Foundation. She was a founding member of the National Institutes of Health Molecular Genetics A study section and is known for high-quality teaching and mentorship. After graduating with a PhD (’90) from Illinois in Biochemistry, Dr. Martinis joined Paul Schimmel's laboratory at MIT as an American Cancer Society Postdoctoral Fellow. Dr. Schimmel is the founder of multiple successful biotech startups and recruited Martinis as one of the initial members of Cubist Pharmaceuticals. Martinis left Cambridge in 1995 for the University of Houston and was recruited back to a tenured position at Illinois in 2005. Martinis has been Head of the Department of Biochemistry and served for one year as interim Associate Dean for the Sciences in the College of Liberal Arts and Sciences, and is currently the Interim Vice Chancellor for Research.

 

"Re-purposing of Ancient Protein Synthesis Enzymes and RNAs for Cell Signaling"

In the first step of translation, aminoacyl-tRNA synthetases (aaRSs) set the genetic code by charging tRNA adaptor molecules with a specific amino acid.  Nature has capitalized upon this ancient family of essential enzymes throughout evolution in all three kingdoms of life to repurpose them for alternate functions that are entirely distinct from protein synthesis.  In human cells, association of multiple aaRSs in a protein complex sequesters many aaRSs’ non-canonical functions.  Alternate functions can also be unleashed by proteolytic cleavage, a splice variant, modifications, or when the aaRS is re-directed from the cytoplasm where protein synthesis occurs to another cellular compartment. Sub-fractionated E. coli cells identified leucyl-tRNA synthetase (LeuRS) that is re-distributed to the periplasmic space.  Under nutritional stresses, periplasmic LeuRS is fragmented, while small amounts of full-length LeuRS and tRNALeu are secreted to the media.  It is hypothesized that E. coli LeuRS plays a non-canonical role as a leucine sensor for cell signaling akin to yeast and mammalian cell LeuRSs.  In addition, extracellular E. coli tRNALeu triggers human cell mobility and socialization suggesting that it might serve as a molecular signal to modulate host-microbe interactions.

 

Susan Martinis