The major goal of this project is to understand how metabolic networks are regulated in response to sudden changes in the concentration of environmental nutrients. While we have a good understanding of central carbon metabolism in various steady states, it is unclear how these metabolic networks adapt to maintain viability on timescales that are too short to alter the composition of the proteome. We focus on how the first step in glycolysis is regulated when cells growing slowly on ethanol are exposed to high enough glucose concentrations to induce the high flux through glycolysis that supports rapid, fermentative growth. Starting glycolysis too fast can deplete ATP and kill cells. Preliminary studies suggest that polymerization of a metabolic enzyme plays a crucial role in regulating the kinetics of this transition. We have found that Glucokinase-1 (Glk1), one of the three enzymes responsible for catalyzing the first step in glycolysis, forms linear polymers when respiring cells encounter high glucose concentrations. Purified Glk1 forms polymers in the presence of glucose and ATP and polymerization inhibits Glk1's catalytic activity. Using genetics, we have demonstrated that deleting GLK1 reduces cell death but slows the acceleration of growth rate when respiring cells encounter glucose. Taking advantage of the conservation of glycolysis across all kingdoms of life, we will investigate the way that starved Saccharomyces cerevisiae's metabolism responds to sudden introduction into glucose-rich media as a tractable model for the general response to rapid increases in the environmental glucose concentration. We will tackle this problem at multiple scales: using a combination of genetics, biochemistry and microscopy to understand how Glk1 and its polymerization affect both glycolysis and cellular growth; using a combination of biochemistry and structural biology in order to elucidate how Glk1 polymerization reduces Glk1 enzymatic activity; and determining the conservation of these mechanisms.

Public Health Relevance

In order to maintain homeostasis, cells must be prepared to respond instantaneously to sudden changes in the quantity and quality of environmental carbon sources. Alteration of how metabolic networks respond to such changes has been implicated in several diseased states (i.e. diabetes and cancer). Thus, we seek to understand the basic mechanisms by which metabolic networks are modulated on short timescales in rapidly changing environments, and how these changes influence cell viability and growth.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
1F31GM116441-01
Application #
8977704
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Barski, Oleg
Project Start
2015-07-15
Project End
2018-07-14
Budget Start
2015-07-15
Budget End
2016-07-14
Support Year
1
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Harvard University
Department
Microbiology/Immun/Virology
Type
Schools of Arts and Sciences
DUNS #
082359691
City
Cambridge
State
MA
Country
United States
Zip Code
Stoddard, Patrick R; Williams, Tom A; Garner, Ethan et al. (2017) Evolution of polymer formation within the actin superfamily. Mol Biol Cell 28:2461-2469