Evolution of Multifunctionalism in Enzymes: Specialist versus Generalist Strategies

Abstract

New ideas concerning nonequilibrium thermodynamics and the concepts of dissipative structures are seen to have profound implications for evolutionary theory. In particular we stress the idea that organisms possess a hierarchy of adaptive possibilities, which result from a construction of nonlinear systems each capable of structural evolution. The genome carries information capable of many "morphogeneses, " as evidenced in enzyme variants. Data are presented to underline the important functional differences of these variants, and an argument put forward to support the latent multifunctional capacity of such macromolecules. A theoretical treatment of the evolution of multifunctional enzymes in the form of specialist versus generalist strategies is given, and it is shown that given considerations about volume swept, binding time, and cost of production, a generalist enzyme will do best in a dilute (or not spatially organized) system, and a specialist enzyme will do best in a dense or channelled environment. The implications of such strategies and stochastic softening of selection upon mutants are then discussed as an alternative to a strict neo-Darwinian approach to evolution.