Jerry D. Cohen

Date & Time: September 23, 2024, at 4 pm

Location: BCH 101

Zoom: https://msu.zoom.us/j/91993518218?pwd=SzN0Umd0dElSblVSOGJEY2U0UzJJdz09
Meeting ID: 919 9351 8218
Passcode: 028299

Host: Yuan Xu

About the Speaker

Institution: University of Minnesota

Subject: Tryptophan, indole and auxin: How systems biology shows promise for discovery

Abstract: The shikimate pathway leads to aromatic amino acids and related metabolites. The branch point at anthranilate synthase is the committed step to forming indolic heterocyclic compounds, a biochemical step of critical importance to biologic processes across kingdoms and leading to pathways still with undefined biochemical reactions. A central output of these processes is the plant hormone auxin, which plays an important role throughout the entire life span of a plant and facilitates its adaptation to a changing environment. Multiple metabolic pathways intersect to control the levels and flux through indole-3-acetic acid (IAA), the primary auxin in most plant species. Measuring changes in these pathways is an important objective to understanding core aspects of auxin signal regulation. Such studies have become approachable through the technologies encompassed by targeted metabolomics allowing simultaneous analysis of biochemical networks. By monitoring the incorporation of stable isotopes from labeled precursors into network intermediates over time, it is possible to trace pathway utilization and characterize new biosynthetic routes to auxin. Chemical inhibitors targeting specific steps or pathways related to auxin synthesis aid these techniques.

Another disputed area of tryptophan metabolism is the kynurenine pathway, which is the principal route of catabolism of the amino acid tryptophan in many organisms. It is clear that the early steps of the kynurenine pathway occur in monocots but not in dicots. The metabolic fate of the later kynurenine pathway intermediates, however, remains uncertain. To meet this challenge and as a complement to our understanding of auxin metabolism, we have focused on untargeted stable isotope tracer approaches for pathway discovery. Using a combination of pathway discovery, network analysis, short time stable isotope label kinetics (SILK) and spatial metabolomics, we seek to decipher the complexity of the metabolic networks that are involved in these critical metabolic activities.