Biomaterial Database

Mechanism of assembly of the outer membrane of Salmonella typhimurium. Translocation and integration of an incomplete mutant lipid A into the outer membrane. 1980

M J Osborn, and P D Rick, and N S Rasmussen

An incomplete precursor of lipid A produced by a mutant of Salmonella typhimurium conditionally defective in synthesis of 3-deoxy-D-mannooctulosonate (KDO) (Rick, P.D., and Osborn, M.J. (1977) J. Biol. Chem. 252, 4895-4903) is poorly translocated to the outer membranes. Approximately 40% of the lipid A precursor synthesized under nonpermissive conditions was recovered in the isolated inner (cytoplasmic) membrane fraction, and the rate of translocation to outer membrane in pulse-chase experiments was only 20% that of lipopolysaccharide. However, integration of the incomplete molecule into the outer membrane appeared to be similar to that of lipopolysaccharide in stability and irreversibility. The ultimate extent of translocation pulse-labeled precursor was comparable to that of lipopolysaccharide and the process was functionally unidirectional. Little or no reverse translocation from outer to inner membrane was detected during conversion of preformed lipid A precursor to lipopolysaccharide following return to permissive conditions.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008050	Lipid A	Lipid A is the biologically active component of lipopolysaccharides. It shows strong endotoxic activity and exhibits immunogenic properties.
D008070	Lipopolysaccharides	Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: LIPID A, core polysaccharide, and O-specific chains (O ANTIGENS). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal B-cell mitogens commonly used in laboratory immunology. (From Dorland, 28th ed)	Lipopolysaccharide,Lipoglycans
D008563	Membrane Lipids	Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.	Cell Membrane Lipid,Cell Membrane Lipids,Membrane Lipid,Lipid, Cell Membrane,Lipid, Membrane,Lipids, Cell Membrane,Lipids, Membrane,Membrane Lipid, Cell,Membrane Lipids, Cell
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D012486	Salmonella typhimurium	A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.	Salmonella typhimurium LT2
D013400	Sugar Acids	MONOSACCHARIDES and other sugars that contain one or more carboxylic acid moieties.	Acids, Sugar