Biochemical Studies of Bacterial Sporulation and Germination: XXIII. NUCLEOTIDE METABOLISM DURING SPORE GERMINATION

Abstract

RNA synthesis, one of the early events in spore germination, is underway by the 2nd min. During the first 10 min of germination, RNA synthesis can proceed in the absence of exogenous nutrients at the expense of previously existing RNA. Salvage pathways for bases, nucleosides, and nucleotides are operative during this period and utilize enzymes which are previously formed in the dormant spore. Biosynthesis of purines and pyrimidines de novo begins approximately 15 to 20 min after the onset of germination. The increase in nucleotide pools sustains an increase in the rate of RNA synthesis. Protein synthesis is necessary for the initiation of nucleotide biosynthesis de novo and one of the enzymes whose synthesis is required is aspartate transcarbamylase. Amino acids generated by the proteolysis during germination are sufficient for synthesis of proteins required for nucleotide biosynthesis de novo and provide the nitrogen source for nucleotide biosynthesis, but exogenous carbon and energy sources must be supplied.