Biomaterial Database

Investigations on the association of phosphatidylserine synthase with the ribosomal component from Escherichia coli. 1980

K Louie, and W Dowhan

The CDP-1,2-diacyl-sn-glycerol (CDP-diacylglycerol):L-serine O-phosphatidyltransferase (EC 2.7.8.8, phosphatidylserine synthase) of Escherichia coli is the first enzyme in the pathway committed to the biosynthesis of the major lipid in E. coli, phosphatidylethanolamine. The enzyme is unique among the phospholipid biosynthetic enzymes due to its high affinity for ribosomes in crude extracts. We report here investigations which define the nature of this in vitro affinity for ribosomes. Phosphatidylserine synthase can be dissociated from ribosomes in the presence of various inorganic salts at high ionic strength. Dissociation was also brought about by cellular levels of the polyamine spermidine. These results suggest the interaction of the enzyme with ribosomes in vitro is primarily ionic in nature, and polyamines may prevent this interaction in vivo. In the presence of nonionic detergent-lipid substrate mixed micelles under assay conditions the enzyme is also dissociated from ribosomes. Dissociation does not occur in the presence of detergent alone or in the presence of lipids which are not substrates or products of the enzyme. This dissociation by lipid substrate indicates the enzyme is not associated with ribosomes during catalysis.

UI	MeSH Term	Description	Entries
D009994	Osmolar Concentration	The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.	Ionic Strength,Osmolality,Osmolarity,Concentration, Osmolar,Concentrations, Osmolar,Ionic Strengths,Osmolalities,Osmolar Concentrations,Osmolarities,Strength, Ionic,Strengths, Ionic
D010717	CDPdiacylglycerol-Serine O-Phosphatidyltransferase	An enzyme that catalyzes the formation of phosphatidylserine and CMP from CDPdiglyceride plus serine. EC 2.7.8.8.	CDP Diacylglycerol-Serine O-Phosphatidyltransferase,CDP Diglyceride Serine O-Phosphatidyltransferase,CDP-DG Synthase,Phosphatidylserine Synthase,Phosphatidylserine Synthetase,CDP DG Synthase,CDP Diacylglycerol Serine O Phosphatidyltransferase,CDP Diglyceride Serine O Phosphatidyltransferase,CDPdiacylglycerol Serine O Phosphatidyltransferase,Diacylglycerol-Serine O-Phosphatidyltransferase, CDP,O-Phosphatidyltransferase, CDP Diacylglycerol-Serine,O-Phosphatidyltransferase, CDPdiacylglycerol-Serine,Synthase, CDP-DG,Synthase, Phosphatidylserine,Synthetase, Phosphatidylserine
D010770	Phosphotransferases	A rather large group of enzymes comprising not only those transferring phosphate but also diphosphate, nucleotidyl residues, and others. These have also been subdivided according to the acceptor group. (From Enzyme Nomenclature, 1992) EC 2.7.	Kinases,Phosphotransferase,Phosphotransferases, ATP,Transphosphorylase,Transphosphorylases,Kinase,ATP Phosphotransferases
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D012270	Ribosomes	Multicomponent ribonucleoprotein structures found in the CYTOPLASM of all cells, and in MITOCHONDRIA, and PLASTIDS. They function in PROTEIN BIOSYNTHESIS via GENETIC TRANSLATION.	Ribosome
D013095	Spermidine	A polyamine formed from putrescine. It is found in almost all tissues in association with nucleic acids. It is found as a cation at all pH values, and is thought to help stabilize some membranes and nucleic acid structures. It is a precursor of spermine.