Metabolite channeling and multi-enzyme complexes

Abstract

The assembly of cooperating enzymes into multicatalytic complexes, also known as metabolons, has become a well-accepted concept in cellular metabolism, at least in principle. There are still relatively few examples where the existence of such systems is supported by solid experimental evidence and even fewer where there is evidence for channeling of metabolites through the complex. However, proteomic approaches are providing new evidence for the pervasiveness of this type of organization, while structural biology is offering insights into how these systems are constructed and regulated. New and improved technologies for analyzing protein interactions and assemblies, both in vitro and in intact cells, are opening the doors to explo-ring the intracellular organization of a growing number of metabolic complexes in plants and other organisms. There is also an increasing appre-ciation of the surprising scale of many protein interaction networks, the multiple functions of individual proteins, and the importance (and challenges) of compartmentalization. As a result, the concept of enzyme complexes is gaining wider acceptance and becoming an increasingly important consideration in efforts to engineer metabolism.