the evolution of enzyme specificity in the metabolic replicator model of prebiotic evolution酶的特异性代谢复制因子的进化的生命起源以前的进化模式.pdf

The Evolution of Enzyme Specificity in the Metabolic Replicator Model of Prebiotic Evolution ´ ¨ 1 ´ ´ ´ 2 Balazs Konnyu˝ , Tamas Czaran * ¨ ¨ ´ 1 Department of Plant Taxonomy and Ecology, Institute of Biology, Eotvos Lorand University, Budapest, Hungary, 2 Theoretical Biology and Ecology Research Group, ¨ ¨ ´ Institute of Biology, Eotvos Lorand University, Budapest, Hungary Abstract The chemical machinery of life must have been catalytic from the outset. Models of the chemical origins have attempted to explain the ecological mechanisms maintaining a minimum necessary diversity of prebiotic replicator enzymes, but little attention has been paid so far to the evolutionary initiation of that diversity. We propose a possible first step in this direction: based on our previous model of a surface-bound metabolic replicator system we try to explain how the adaptive specialization of enzymatic replicator populations might have led to more diverse and more efficient communities of cooperating replicators with two different enzyme activities. The key assumptions of the model are that mutations in the replicator population can lead towards a) both of the two different enzyme specificities in separate replicators: efficient ‘‘specialists’’ or b) a ‘‘generalist’’ replicator type with both enzyme specificities working at less efficiency, or c) a fast- replicating, non-enzymatic ‘‘parasite’’. We show that under realistic trade-off constraints on the phenotypic effects of these mutations the evolved replicator communit