Effects of Environment (Radiation, Substrate and Allelic Genes) on the Melezitose Gene in Saccharomyces

Abstract

THE melezitose locus (MZ) in Saccharomyces controls the formation of the adaptive enzyme, melezitase, which acts on five substrates : turanose (T), maltose (M), sucrose (S), methyl-α-D-glucopyranoside (G), and melezitose (Z), each of which may serve as an inducer of melezitase^1–3. Seven different variations (alleles) of this gene are known and are designated TMSGZ, TMSGz, TMSgZ, TMSgz, TMsgz, Tmsgz and tmsgz ³. The capital letters indicate the substrates which are capable of inducing melezitase in glucose-grown cultures. Cells in which melezitase has been induced by one of the substrates to which it responds adaptively are able to split the substrates which do not act as inducers in that specific genotype without further adaptation. For example, a glucose-grown culture carrying TMSgz responds to neither methyl-α-D-glucopyranoside nor melezitose, but splits both these substrates after exposure to turanose, maltose or sucrose.