PMID:6361023
| Citation |
Bulawa, CE, Hermes, JD and Raetz, CR (1983) Chloroform-soluble nucleotides in Escherichia coli. Role of CDP-diglyceride in the enzymatic cytidylylation of phosphomonoester acceptors. J. Biol. Chem. 258:14974-80 |
|---|---|
| Abstract |
CDP-diglyceride, the precursor of all the phospholipids in Escherichia coli, is cleaved in vitro to phosphatidic acid and CMP by a membrane-bound hydrolase. Since the physiological function of CDP-diglyceride hydrolase is unknown, we have explored the possibility that this enzyme acts in vivo as either a phosphatidyl- or cytidylyltransferase. To distinguish between these two alternatives, partially purified hydrolase was incubated with CDP-diglyceride in the presence of 50% H218O. Analysis of the reaction products by 31P NMR showed that 18O is incorporated exclusively into CMP, suggesting that the enzyme is a cytidylyltransferase. This conclusion is further supported by the following experimental results: (i) the hydrolase catalyzes the transfer of CMP from CDP-diglyceride to Pi; (ii) numerous phosphomonoesters, such as glycerol 3-phosphate, phosphoserine, and glucose 1-phosphate also function as CMP acceptors, but the corresponding compounds lacking the phosphate residues are not substrates for the enzyme; and (iii) CDP-diglyceride hydrolase exchanges [32P]phosphatidic acid for the phosphatidyl moiety of CDP-diglyceride and 32Pi for the beta-phosphate residue of CDP, indicating the involvement of a novel CMP-enzyme complex. These data suggest a biosynthetic role for CDP-diglyceride hydrolase, and extend the possible functions of CDP-diglyceride in the E. coli envelope. |
| Links | |
| Keywords |
Chloroform; Cytidine Diphosphate Diglycerides/metabolism; Cytidine Monophosphate/metabolism; Escherichia coli/genetics; Hydrolases/metabolism; Magnetic Resonance Spectroscopy; Models, Chemical; Nucleoside Diphosphate Sugars/metabolism; Nucleotides/metabolism; Phosphatidic Acids/metabolism; Solubility |
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