Biomaterial Database

Membrane protein acylation. Preference for exogenous myristic acid or endogenous saturated chains in Acholeplasma laidlawii. 1992

S Nyström, and P Wallbrandt, and A Wieslander

Department of Biochemistry, University of Umeå, Sweden.

Mycoplasmas are small bacteria without a cell wall, often found as surface parasites on eukaryotic cells. Of the more than 200 membrane proteins from Acholeplasma laidlawii resolved by two-dimensional PAGE, 23 were covalently modified with acyl chains. These acyl proteins had lower pI values than average and were all labelled by different exogenously supplied radioactive fatty acids attached by O-ester bonds. The fatty acids were selectively incorporated in the order myristic acid (14:0) greater than palmitic acid (16:0) greater than stearic acid (18:0) greater than oleic acid (18:1). However, endogenously synthesised saturated fatty acids, most of which were 16:0, were preferred over the supplied ones. A fraction of the exogenous 14:0 was elongated to 16:0. Absence of saturated fatty acids increased the incorporation of 18:1. The maximum extent of modification was one acyl chain for protein T2, on the exterior surface and two acyl chains for protein D12, spanning them membrane. Exogenously supplied fatty acids were incorporated into membrane lipids in proportion to their occurrence. However, the acylated proteins always contained 8-10 times more saturated chains than did the lipids. When exogenously supplied, all A. laidlawii polar membrane lipids could donate acyl chains to the acylated proteins but the neutral fraction (fatty acids and diacylglycerol) was most efficient. An incorporation into the acylated proteins of labelled cysteine, but not glucose or glycerol, was observed. Acylated proteins with different chains interacted similarly with a Triton X-114 detergent phase, and no full-size proteins (or acylated fragments) were released from cells by proteolytic enzymes. The results indicate an anchoring with peptide segments in addition to the acyl chains. Both 14:0 and 16:0 were attached at one end of both T2 and D12, but the N-terminal methionine of T2 was not acylated. The extent of modification and preference for saturated chains in the A. laidlawii membrane acylated proteins is more similar to eukaryotic than to eubacterial proteins.

UI	MeSH Term	Description	Entries
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
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D009227	Myristic Acids	14-carbon saturated monocarboxylic acids.	Tetradecanoic Acids,Acids, Myristic,Acids, Tetradecanoic
D011092	Polyethylene Glycols	Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.	Macrogols,Polyoxyethylenes,Carbowax,Macrogol,Polyethylene Glycol,Polyethylene Oxide,Polyethyleneoxide,Polyglycol,Glycol, Polyethylene,Glycols, Polyethylene,Oxide, Polyethylene,Oxides, Polyethylene,Polyethylene Oxides,Polyethyleneoxides,Polyglycols,Polyoxyethylene
D003545	Cysteine	A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.	Cysteine Hydrochloride,Half-Cystine,L-Cysteine,Zinc Cysteinate,Half Cystine,L Cysteine
D004952	Esters	Compounds derived from organic or inorganic acids in which at least one hydroxyl group is replaced by an –O-alkyl or another organic group. They can be represented by the structure formula RCOOR’ and are usually formed by the reaction between an acid and an alcohol with elimination of water.	Ester
D005227	Fatty Acids	Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)	Aliphatic Acid,Esterified Fatty Acid,Fatty Acid,Fatty Acids, Esterified,Fatty Acids, Saturated,Saturated Fatty Acid,Aliphatic Acids,Acid, Aliphatic,Acid, Esterified Fatty,Acid, Saturated Fatty,Esterified Fatty Acids,Fatty Acid, Esterified,Fatty Acid, Saturated,Saturated Fatty Acids
D005947	Glucose	A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.	Dextrose,Anhydrous Dextrose,D-Glucose,Glucose Monohydrate,Glucose, (DL)-Isomer,Glucose, (alpha-D)-Isomer,Glucose, (beta-D)-Isomer,D Glucose,Dextrose, Anhydrous,Monohydrate, Glucose
D005990	Glycerol	A trihydroxy sugar alcohol that is an intermediate in carbohydrate and lipid metabolism. It is used as a solvent, emollient, pharmaceutical agent, or sweetening agent.	1,2,3-Propanetriol,Glycerin,1,2,3-Trihydroxypropane,Glycerine
D000128	Acholeplasma laidlawii	An organism originally isolated from sewage, manure, humus, and soil, but recently found as a parasite in mammals and birds.	Mycoplasma laidlawii