Polymerization in the actin ATPase clan regulates hexokinase activity in yeast

Abstract

Polymerization regulates hexokinase activity The yeast hexokinase Glk1 is an actin-fold protein that forms polymers in response to binding its substrates and products. Stoddard et al. now show that Glk1 polymers are structurally distinct from actin filaments and suggest that polymerization of Glk1 evolved independently of the polymerization of other actin-like polymers. Glk1 polymerization inhibits its hexokinase activity, and the monomerpolymer equilibrium appears to set a maximum rate for the entire enzyme pool rather than a maximum rate per enzyme. This inhibition was found to be important for cell viability in the context of nutrient shifts, allowing yeast cells to modulate their metabolism rapidly in response to stochastic changes in the environment. Science , this issue p. 1039