THE METABOLISM OF 4-AMINOBUTYRATE (GABA) IN FUNGI

Information on the genetics and metabolism of 4-aminobutyrate (GABA) i n yeasts and fungi is reviewed. In spite of ubiquitous occurrence, the re is limited information on its function and biological role. Most fu ngi utilize GABA both as a carbon and a nitrogen source. Fungal endoge nous GABA largely originates from the decarboxylation of L-glutamate a nd is associated with sporulation/spore metabolism. Whatever its sourc e, GABA is catabolized to succinate via succinicsemialdehyde. Taken to gether these steps define a potential bypass outside the classical tri carboxylic acid cycle. Evidence for the existence of such a functional bypass in fungi is reviewed. The role of GABA and its metabolism in v arious facets of fungal biology is gradually emerging.