Distributed Control of the Pentose Phosphate Pathway in Yeast

Abstract

In this work, genetic perturbations at enzymes of the pentose phosphate pathway (PPP) in yeast are used to identify points where the flux through the pathway is regulated. First, a new tool for measuring the PPP is introduced. A recently developed system for induction of gene expression in yeast and novel insights into metabolic flux analysis of the PPP are the backdrop for the development of a new PPP flux assay. The inducible expression system and the PPP assay are then used to screen a group of two dozen potential regulators identified as having a role in traditional or metabolic control theoretic approaches to pathway regulation. Of these, Zwf1p and Ald6p are verified as enzymes whose activity regulates PPP flux positively and negatively, respectively. Other points of control for the PPP include Gnd1p, Pfk1p, Tal1p, and Rki1p. The mechanisms behind the action of these new pathway controllers are explored using the flux assay and metabolomics data and new regulatory interactions, including 6-phosphogluconate inhibition of Zwf1p and PGI1p, are proposed.