Phosphoproteins in Escherichia coli.

Rafter, Gale W. (The Johns Hopkins School of Medicine and School of Hygiene and Public Health, Baltimore, Md.) and William C. Lane. Phosphoproteins in Escherichia coli. J. Bacteriol. 83:1077-1083. 1962.-The identification and metabolism of phosphoprotein were investigated in Escherichia coli. Hydrolysis of bacterial protein fractions with barium hydroxide or with phosphoprotein phosphatase released acid-soluble phosphorus. Chromatography of acid-hydrolyzed and incubated fractions also indicated the presence of phospho-amino acids. Turnover of phosphate in protein of growing cells was not observed, but incorporation of phosphate into protein of nongrowing cells was found. The protein-phosphate content decreased as organisms passed from the growing to the nongrowing state. The phosphoprotein composition, as revealed by paper electrophoresis, was heterogeneous. No protein phosphokinase or protein-phosphate phosphatase was detected in cell-free extracts, but an active principle which catalyzed the formation of acid-soluble phosphate from bacterial protein fractions was found.