Biochemical Studies of Bacterial Sporulation and Germination: VI. ORIGIN OF SPORE CORE AND COAT PROTEINS

Abstract

Abstract Bacillus subtilis spore proteins were separated into two major fractions. One fraction, released by mechanical disruption into a soluble form, constitutes 20% of the spore protein and is designated the core fraction. It resembles in amino acid composition the protein of the cell early in sporulation and includes many of the cellular enzymes. The other 80% of spore proteins are in a particulate form after spore breakage and are designated the coat fraction. These proteins have an amino acid composition distinct from the core fraction and are heterogeneous. Studies on the synthesis of core and coat proteins, by labeling with tritiated phenylalanine, showed that protein of the core fraction is newly synthesized during sporulation to the extent of at least 75 to 90%, and protein in the coat fraction to the extent of 95%. The kinetics of labeling suggests an early synthesis of core proteins followed by that of coat proteins. The core proteins newly synthesized during the sporulation period, as well as those apparently borrowed from the vegetative cell, represent a large variety of protein species, including those of the ribosomes.