Initiation of spore germination in Bacillus subtilis: relationship to inhibition of l alanine metabolism

Abstract

The inhibitory effects of anthranilic acid esters (methyl anthranilate and N methyl anthranilate) on the L alanine induced initiation of spore germination was examined in B. subtilis 168. Methyl anthranilate irreversibly inhibited alanine initiation by a competitive mechanism. In its presence, the inhibition could be reversed only by the combined addition of D glucose, D fructose, and K+. Both L alanine dehydrogenase and L glutamate pyruvate transaminase, enzymes which catalyze the first reaction in L alanine metabolism, were competitively inhibited by methyl anthranilate. The Ki values for germination initiation (0.053 mM) and of L glutamate pyruvate transaminase (0.068 mM) were similar, whereas that for L alanine dehydrogenase (0.4 mM) was 6 to 7 times higher. Since a mutant lacking L alanine dehydrogenase activity germinated normally in L alanine alone it is speculated that the major pathway of L alanine metabolism during initiation may be via transamination reaction.