Periplasmic glycerophosphodiester phosphodiesterase of Escherichia coli, a new enzyme of the glp regulon

• Published in: The Journal of biological chemistry 1983-05, Vol.258 (9), p.5428-5432
• Main Authors: Larson, T J, Ehrmann, M, Boos, W
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - analysis; Biological Transport, Active; Cations, Divalent - pharmacology; Escherichia coli - enzymology; Glycerophosphates - metabolism; Kinetics; Phosphoric Diester Hydrolases - genetics; Phosphoric Diester Hydrolases - metabolism; Substrate Specificity
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(20)81908-5

The promoter-proximal gene (glpT) of the glpT-glpQ operon of Escherichia coli encodes a membrane permease responsible for active transport of sn-glycerol 3-phosphate. Promoter-distal glpQ encodes a periplasmic protein which is not required for active transport of sn-glycerol 3-phosphate (Larson, T.J., Schumacher, G., and Boos, W. (1982) J. Bacteriol. 152, 1008-1021). This periplasmic protein has now been identified as a phosphodiesterase which hydrolyzes glycerophosphodiesters into sn-glycerol 3-phosphate plus alcohol. The enzyme exhibited broad substrate specificity with respect to the alcohol moiety; sn-glycerol 3-phosphate was released from glycerophosphoethanolamine, glycerophosphocholine, glycerophosphoglycerol, and bis(glycerophospho)glycerol. The enzyme was specific for glycerophosphodiesters; bis(p-nitrophenyl)phosphate, a substrate for other phosphodiesterases, was not hydrolyzed. In a coupled spectrophotometric assay utilizing sn-glycerol 3-phosphate dehydrogenase and NAD, apparent activity was optimal at pH 9 and was stimulated by Ca2+. The substrates of the phosphodiesterase had no affinity for the glpT-encoded active transport system. Thus, the glpQ gene product expands the catabolic capability of the glp regulon to include a variety of glycerophosphodiesters.