Activation of mannosyltransferase II by nonbilayer phospholipids

Jensen, John W.; Schutzbach, John S.

doi:10.1021/bi00301a012

Cited by 87 publications

(42 citation statements)

References 19 publications

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“…T h e same results for phospholipid specificity were obtained, (a) when enzyme was present during hydration of the phospholipid, followed by mixing on a vortex mixer for 30 s, (b) when the enzyme/phospholipid mixtures were immersed in a bath sonifier for 10 s, and (c) when enzyme and sonically dispersed phospholipids were subjected t o five cycles of freezing and thawing in a solid C02/acetone bath prior t o assay. The same specificity was also observed when the enzyme was reconstituted with phospholipids by detergent-dilution methods [20,211, o r when detergent was removed with a hydrophobic matrix (Bio-Beads SM-2) following co-solubilization of enzyme, phospholipid, and dolichyl-P with detergent ( Table 3 …”

Section: Activation Of Enzyme Activity By Phospholipidsmentioning

confidence: 63%

“…The addition of increasing quantities of unsaturated PtdCho to dispersions of unsaturated PtdEtn has been shown to induce a transition from hexagonal phase to stable bilayers [22 -241 and dolichol was found to promote the destabilizing effect of PtdEtn on bilayer structure [20,251. Enzyme activity was therefore assessed in mixtures of phospholipids containing PtdEtn and PtdCho at several concentrations of dolichyl-P (Fig.…”

Section: Enzyme Activity In Menzhranes Of' Mixed Compositionmentioning

confidence: 99%

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Activation of dolichyl‐phospho‐mannose synthase by phospholipids

Jensen

Schutzbach

1985

European Journal of Biochemistry

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Dolichyl-phospho-mannose synthase, or C1DPmannose:dolichyLphosphate mannosyltransferase (EC 2.4.1.831, was solubilized from rat liver microsomes with 2 .O% Nonidet P-40 and the enzyme was further purified by column chromatography on DEAE-cellulose in the presence of 0.1% Nonidet P-40. The purified enzyme preparation (880-fold over microsomes) was unstable in the presence of detergent and had no activity in the presence of Nonidet P-40, Triton X-100, octyl b-glucoside, or deoxycholate. Detergent-free enzyme was active in the presence of phosphatidylethanolamine (PtdEtn) and in the presence of phospholipid mixtures of PtdEtn and phosphatidylcholine (PtdCho) when the molar proportion of PtdCho was 70% or less. These results suggest that dolichyl-P-mannose synthase is optimally active in a phospholipid matrix that contains some component phospholipids that prefer non-bilayer structural organization in isolation. Heat-inactivation and sedimentation experiments demonstrated that the synthase associated with PtdEtn in the presence of dolichyl-P. The PtdEtn-reconstituted enzyme catalyzed the reversible transfer of mannose from GDP-mannose to dolichyl-P. The K,,, for GDP-mannose was found to be 0.69 pM and the apparent K,,, for dolichyl-P was 0.3 pM. GMP, GDP, and GTP inhibited mannosyltransfer 50% at concentrations of 16 pM, 1.3 pM and 3 pM respectively.GDPmannose : dolichyl-phosphate mannosyltransferase (EC 2.4.1.83) is involved in the formation of a key intermediate in glycoprotein biosynthesis. Although a large number of investigations have been carried out with this enzyme [I -51, the enzyme has never been substantially purified from mammalian tissues. Heifetz and Elbein [6] reported a 5-fold purification of the enzyme from porcine aorta, but the enzyme was unstable and was only partially characterized. Babczinski et al. [7] and Haselbeck and Tanner [8] have purified the enzyme 280-fold from yeast membranes, and Carlo and Villemez have studied a soluble form of the enzyme isolated from Acurztkamoeha costrlluni [9]. The yeast enzyme was shown to be active, both in nonionic detergents and when reconstituted into liposomes composed of commercial grade plant lecithin [8]. We would now like to report a greatly improved purification of the mannosyltransferase from rat liver microsomes. In contrast to the aorta and yeast enzymes, the partially purified liver enzyme was quite stable. Crude microsomal and solubilized preparations of the enzyme were active in the presence of nonionic detergents, but more highly Abbreviations. PtdCho, phosphatidylcholine; PtdELn, phosphatidylethanolaminc: Ptdlns, phosphatidylinositol; PtdSer, phosphatidylserine. These and other lipid abbreviations (see Table 2) follow IUB Recommendations, see Eur. J. Biochem. 7Y, 11 -21 (1977) and Eur. J. Biochem. 104, 322 (1980). E n q m e s . Dolichyl-phospho-mannose synthase, GDPmannose : dolichyl-phosphate mannosyltransferase (EC 2.4.1 3 3 ) ; mannosyltransferase 11, GDPmannose : glycolipid 1,3-~-~-mannosyltransferase (EC 2.4.1.132).~~ purified enzyme f...

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Section: Activation Of Enzyme Activity By Phospholipidsmentioning

confidence: 63%

Section: Enzyme Activity In Menzhranes Of' Mixed Compositionmentioning

confidence: 99%

Activation of dolichyl‐phospho‐mannose synthase by phospholipids

Jensen

Schutzbach

1985

European Journal of Biochemistry

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“…Moreover, phosphatidylethanolamine with cis unsaturated fatty acyl chains is known to favor the formation of nonbilayer lipid phases in membranes under physiological conditions (7). Such transitory nonbilayer structures might be required to minimize packing defects around the irregular surfaces of membrane proteins (36), to activate membrane-bound enzymes (5,23,32), and to optimize membrane functions such as facilitated membrane transport (7). Thus, the observed changes could facilitate the insertion or function of membranebound Alk proteins.…”

Section: Discussionmentioning

confidence: 99%

Growth on octane alters the membrane lipid fatty acids of Pseudomonas oleovorans due to the induction of alkB and synthesis of octanol

Chen

Janssen

1995

J Bacteriol

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Growth of Pseudomonas oleovorans GPo1, which contains the OCT plasmid, on octane results in changes in the membrane phospholipid fatty acid composition. These changes were not found for GPo12, an OCTplasmid-cured variant of GPo1, during growth in the presence or absence of octane, implying the involvement of OCT-plasmid-encoded functions. When recombinant strain GPo12(pGEc47) carrying the alk genes from the OCT plasmid was grown on octane, the cells showed the same changes in fatty acid composition as those found for GPo1, indicating that such changes result from induction and expression of the alk genes. This finding was corroborated by inducing GPo12(pGEc47) with dicyclopropylketone (DCPK), a gratuitous inducer of the alk genes. Further experiments showed that the increase of the mean acyl chain length of fatty acids is related to the expression of alkB, which encodes a major integral membrane protein, while the formation of trans unsaturated fatty acids mainly results from the effects of 1-octanol, an octane oxidation product.Pseudomonas oleovorans is able to use n-alkanes with 6 to 12 carbon atoms as the sole carbon and energy sources (1). The cells can be grown in two-liquid-phase medium, composed of an aqueous phase and a bulk alkane phase at volume fractions from 5 to 95% (vol/vol) n-octane (28). The enzymes that convert n-alkanes to acyl coenzyme A are encoded by the alk genes, which are located on the OCT plasmid ( Fig. 1) (10-13, 26, 37). The AlkB component of the alkane hydroxylase is a major membrane protein, which accounts for 25 to 30% of the total cytoplasmic membrane protein content of P. oleovorans (12,28).When grown in a two-liquid-phase medium, containing a bulk n-octane phase, the cellular membranes of P. oleovorans are altered, as seen by freeze-fracture electron microscopy (8, 34), by lipid fatty acid analysis, and by membrane fluidity measurements (4). In particular, the membrane fatty acid composition changes: more 18:1 fatty acids, more unsaturated fatty acids, and trans unsaturated fatty acids are formed. As a result of these changes, the transition temperature of the membrane lipid increases by about 20ЊC (4), which compensates for the potential bilayer fluidizing effects of n-octane (30).When P. oleovorans is grown on n-octane in two-liquidphase medium, the cells are exposed to a bulk octane phase. In addition, the alk genes are induced, and as a consequence, n-octane is oxidized. Since both organic solvents and membrane proteins can influence membrane lipid composition and properties (21,30,40,41), two alternative hypotheses can explain the above effects. First, membrane lipid changes are only a general effect of exposure of P. oleovorans to n-octane. Second, membrane lipid changes are related specifically to the presence and activity of the alk genes in P. oleovorans.To test these two hypotheses, we have compared the effects of growth in (or on) octane and the effects of inducing the alk genes on the fatty acid composition of three types of P. oleovorans strains: GPo1, the wild-ty...

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“…Indeed the structural rearrangement of the type : bilayer (L) e hexagonal phase (HI,) was recently found to influence the catalytic activity of some enzymes (phospholipases, phosphodiesterases, ATPase and manosyltransferase) entrapped into proteoliposomes [lo, [45][46][47][48][49] '.…”

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confidence: 99%

Catalysis by enzymes entrapped into hydrated surfactant aggregates having lamellar or cylindrical (hexagonal) or ball‐shaped (cubic) structure in organic solvents

Klyachko

Levashov

Pshezhetsky

et al. 1986

European Journal of Biochemistry

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Instead of aqueous solutions, universally recognized in enzymology, ternary systems of the waterlorganic solvent/surfactant type are suggested as liquid-crystalline media for enzymatic reactions. Two systems, water/ octane/Aerosol OT and water/cyclohexane/Brij 96, have been used to solubilize acid and alkaline phosphatases and peroxidase. The enzymes under study do function in liquid-crystalline mesophases having lamellar, cylindrical (reversed hexagonal) and ball-shaped (reversed cubic) packing of the surfactant molecules. A significant result is that the phase transition from one liquid-crystalline structure to another entails, as a rule, a reversible change in the catalytic activity of the solubilized enzyme.There is no doubt that the lipid bilayer forms the framework of biological membranes and provides the barrier function [I]. Recently, however, a clear understanding has been achieved of the role that might be played in membranes by lipid polymorphism and local transitions between lamellar (bilayer) and hexagonal lipid phases [2 -171. The topic under discussion is the formation in membranes of hexagonally packed cylinders, in which the polar head groups of lipid molecuies line the narrow channel filled with water. It also seems possible that, inside the lipid bilayer, smaller associates of lipid molecules spring up, almost spherical and built like reversed micelles (lipid particles). The driving forces of such rearrangements in membranes and a possible biological role of non-bilayer structures were discussed in some recent reviews [14, 15,[18][19][20][21][22].These new ideas cause new enzymological problems since the overwhelming majority of enzymes in vivo function on the surface of biological membranes or inside them [23 -301. It is, therefore, important to elicit first whether enzymes can, in principle, possess catalytic activity if they are entrapped into microheterogeneous aggregates (of the types of lamellas, cylinders and/or ball-shaped micelles) built from lipid molecules. Second, whether the catalytic activity of the entrapped enzymes alters after the transition from one type of packing of lipid molecules to another.The problem of lipid dependence of enzymes has long been under discussion [31-401. As the chief regulatory factors (in addition to specific lipid-protein interactions, see for instance [41,42]), the microviscosity [35,39,401 Another regulatory factor might be the capacity of liquid crystals for polymorphism; for review, see monographs [18, 441. Indeed the structural rearrangement of the type : bilayer (L) e hexagonal phase (HI,) was recently found to influence the catalytic activity of some enzymes (phospholipases, phosphodiesterases, ATPase and manosyltransferase) entrapped into proteoliposomes [lo, 45-49] '.In our opinion, a handier way to solve the membranological problems of this kind derives from the solubilization of enzymes in microheterogeneous media of the water/organic solvent/surfactant type [22]. The point is that the amphiphilic molecules of surfactants in water/organ...

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Activation of mannosyltransferase II by nonbilayer phospholipids

Cited by 87 publications

References 19 publications

Activation of dolichyl‐phospho‐mannose synthase by phospholipids

Activation of dolichyl‐phospho‐mannose synthase by phospholipids

Growth on octane alters the membrane lipid fatty acids of Pseudomonas oleovorans due to the induction of alkB and synthesis of octanol

Catalysis by enzymes entrapped into hydrated surfactant aggregates having lamellar or cylindrical (hexagonal) or ball‐shaped (cubic) structure in organic solvents

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