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PhD Exit Seminar – Stephanie Marie Prezioso (Christendat lab)

May 2, 2017 @ 2:00 pm - 3:00 pm

PhD Exit Seminar

Tuesday May 2nd, 2:10 pm – Ramsay Wright Building, Rm. 432


Stephanie Marie Prezioso (Christendat lab)


“Identifying the Functions and Regulatory Mechanisms of Shikimate Dehydrogenase Homologs in Bacteria”




The shikimate pathway is required for synthesis of the aromatic amino acids as well as other aromatic compounds in bacteria. The prototypical member of the shikimate dehydrogenase (SDH) enzyme family, AroE, catalyzes the fifth step in this pathway; the reduction of dehydroshikimate to shikimate. In addition to AroE, four other SDH family members have been identified: YdiB, Ael1, RifI, and SdhL. However, the metabolic functions of Ael1, RifI, and SdhL are poorly characterized, and few studies focus on the regulation of SDH enzymes. This thesis investigates the biological functions of the SDH family of enzymes, and explores the systems that govern their expression in bacteria.


We use Pseudomonas putida to investigate the functions of the SDH family of enzymes, as it has one representative homolog of each family member. The differences in expression profiles observed among these SDH homologs in P. putida, along with existing kinetic data, suggest that each homolog performs a distinct biological role related to the shikimate pathway. Additionally, we identified multiple novel metabolic disturbances due to SDH disruptions in P. putida that allow us to propose putative roles for the SDH enzymes in bacterial metabolism.


The quinate utilization operons in Listeria monocytogenes encode two SDH proteins among other enzymes that act in the quinate/shikimate utilization metabolic pathway. These operons are activated by a LysR Type Transcriptional Regulator (LTTR), called QuiR1, in response to shikimate. The structure of the QuiR1 effector binding domain with shikimate bound reveals overall LTTR structural conservation as well as the architecture of the shikimate binding site. This work sheds light on the mechanism of transcriptional regulation of the genes encoding enzymes involved in metabolism of the plant derived compound quinate, as well as shikimate, in L. monocytogenes. This intricate regulation may allow for an optimized metabolic response to changing environmental conditions.


Ramsay Wright is a wheelchair accessible building.



May 2, 2017
2:00 pm - 3:00 pm
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Ramsay Wright Building, Room 432
25 Harbord St.
Toronto, ON M5S 3G5 Canada