scholarly journals Some properties, including the substrate in vivo, of the Δ9-desaturase in Micrococcus cryophilus

1983 ◽  
Vol 209 (2) ◽  
pp. 345-353 ◽  
Author(s):  
M Foot ◽  
R Jeffcoat ◽  
N J Russell
Keyword(s):  
Desaturase Activity ◽  
Acyl Carrier Protein ◽  
Thiol Group ◽  
Carrier Protein ◽  
Psychrophilic Bacterium ◽  
Ph Optimum ◽  
Δ9 Desaturase ◽  
Membrane Bound ◽  
Delta 9 Desaturase

The delta 9-desaturase of the psychrophilic bacterium Micrococcus cryophilus is shown to be a membrane-bound enzyme that is probably linked to a cyanide- (and azide-) sensitive respiratory chain with oxygen as the final acceptor. It has a pH optimum of 8.7 and contains an essential thiol group, but has no special ion requirements. The desaturase activity of washed membranes could not be increased by adding supernatant or NADH and NADPH, possibly owing to the endogenous generation of reduced cofactors by the membranes. The substrate for the desaturase is not acyl-CoA and is probably not acyl-acyl-carrier protein. Evidence is presented that the substrate in vivo is saturated phospholipid and a scheme for the possible routes of incorporation of exogenous stearic acid into oleoyl-phospholipid is presented.

scholarly journals Plant holo-(acyl carrier protein) synthase

1988 ◽  
Vol 252 (1) ◽  
pp. 39-45 ◽  
Author(s):  
S A Elhussein ◽  
J A Miernyk ◽  
J B Ohlrogge
Keyword(s):  
Spinacia Oleracea ◽  
Acyl Carrier Protein ◽  
Ricinus Communis ◽  
Plant Cells ◽  
Gel Permeation Chromatography ◽  
Carrier Protein ◽  
Improved Method ◽  
Ph Optimum ◽  
Spinach Leaf

1. An improved method was developed for the assay of plant holo-(acyl carrier protein) synthase activity, using Escherichia coli acyl-(acyl carrier protein) synthetase as a coupling enzyme. 2. Holo-(acyl carrier protein) synthase was partially purified from spinach (Spinacia oleracea) leaves by a combination of (NH4)2SO4 fractionation and anion-exchange and gel-permeation chromatography. 3. The partially purified enzyme had a pH optimum of 8.2 and Km values of 2 microM, 72 microM and 3 mM for apo-(acyl carrier protein), CoA and Mg2+ respectively. Synthase activity was inhibited in vitro by the reaction product 3′,5′-ADP. 4. Results from the fractionation of spinach leaf and developing castor-oil-seed (Ricinus communis) endosperm cells were consistent with a cytosolic localization of holo-(acyl carrier protein) synthase activity in plant cells.

scholarly journals In Vitro Inhibition of the Mycobacterium tuberculosis β-Ketoacyl-Acyl Carrier Protein Reductase MabA by Isoniazid

2004 ◽  
Vol 48 (1) ◽  
pp. 242-249 ◽  
Author(s):  
Stéphanie Ducasse-Cabanot ◽  
Martin Cohen-Gonsaud ◽  
Hedia Marrakchi ◽  
Michel Nguyen ◽  
Didier Zerbib ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
Dynamic Equilibrium ◽  
Acyl Carrier Protein ◽  
Multidrug Resistant ◽  
Carrier Protein ◽  
Ligand Complex ◽  
Fas Ii

ABSTRACT The first-line specific antituberculous drug isoniazid inhibits the fatty acid elongation system (FAS) FAS-II involved in the biosynthesis of mycolic acids, which are major lipids of the mycobacterial envelope. The MabA protein that catalyzes the second step of the FAS-II elongation cycle is structurally and functionally related to the in vivo target of isoniazid, InhA, an NADH-dependent enoyl-acyl carrier protein reductase. The present work shows that the NADPH-dependent β-ketoacyl reduction activity of MabA is efficiently inhibited by isoniazid in vitro by a mechanism similar to that by which isoniazid inhibits InhA activity. It involves the formation of a covalent adduct between MnIII-activated isoniazid and the MabA cofactor. Liquid chromatography-mass spectrometry analyses revealed that the isonicotinoyl-NADP adduct has multiple chemical forms in dynamic equilibrium. Both kinetic experiments with isolated forms and purification of the enzyme-ligand complex strongly suggested that the molecules active against MabA activity are the oxidized derivative and a major cyclic form. Spectrofluorimetry showed that the adduct binds to the MabA active site. Modeling of the MabA-adduct complex predicted an interaction between the isonicotinoyl moiety of the inhibitor and Tyr185. This hypothesis was supported by the fact that a higher 50% inhibitory concentration of the adduct was measured for MabA Y185L than for the wild-type enzyme, while both proteins presented similar affinities for NADP+. The crystal structure of MabA Y185L that was solved showed that the substitution of Tyr185 induced no significant conformational change. The description of the first inhibitor of the β-ketoacyl reduction step of fatty acid biosynthesis should help in the design of new antituberculous drugs efficient against multidrug-resistant tubercle bacilli.

scholarly journals The Burkholderia pseudomallei Enoyl-Acyl Carrier Protein Reductase FabI1 Is Essential forIn VivoGrowth and Is the Target of a Novel Chemotherapeutic with Efficacy

2013 ◽  
Vol 58 (2) ◽  
pp. 931-935 ◽  
Author(s):  
Jason E. Cummings ◽  
Luke C. Kingry ◽  
Drew A. Rholl ◽  
Herbert P. Schweizer ◽  
Peter J. Tonge ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Fatty Acid Biosynthesis ◽  
Acyl Carrier Protein ◽  
Specific Inhibitor ◽  
Carrier Protein ◽  
Wild Type ◽  
Content Type ◽  
Fatty Acid Biosynthesis Pathway ◽  
Enoyl Acp Reductase

ABSTRACTThe bacterial fatty acid biosynthesis pathway is a validated target for the development of novel chemotherapeutics. However, sinceBurkholderia pseudomalleicarries genes that encode both FabI and FabV enoyl-acyl carrier protein (ACP) reductase homologues, the enoyl-ACP reductase that is essential forin vivogrowth needs to be defined so that the correct drug target can be chosen for development. Accordingly, ΔfabI1, ΔfabI2, and ΔfabVknockout strains were constructed and tested in a mouse model of infection. Mice infected with a ΔfabI1strain did not show signs of morbidity, mortality, or dissemination after 30 days of infection compared to the wild-type and ΔfabI2and ΔfabVmutant strains that had times to mortality of 60 to 84 h. Although signs of morbidity and mortality of ΔfabI2and ΔfabVstrains were not significantly different from those of the wild-type strain, a slight delay was observed. A FabI1-specific inhibitor was used to confirm that inhibition of FabI1 results in reduced bacterial burden and efficacy in an acuteB. pseudomalleimurine model of infection. This work establishes that FabI1 is required for growth ofBurkholderia pseudomalleiin vivoand is a potential molecular target for drug development.

scholarly journals A Conserved Histidine Is Essential for Glycerolipid Acyltransferase Catalysis

1998 ◽  
Vol 180 (6) ◽  
pp. 1425-1430 ◽  
Author(s):  
Richard J. Heath ◽  
Charles O. Rock
Keyword(s):  
Aspartic Acid ◽  
Acyl Carrier Protein ◽  
Site Directed Mutagenesis ◽  
Carrier Protein ◽  
Synthetase Activity ◽  
Acyltransferase Activity ◽  
Acyl Acceptor ◽  
Aspartic Acid Residue ◽  
Membrane Bound

ABSTRACT Sequence analysis of membrane-bound glycerolipid acyltransferases revealed that proteins from the bacterial, plant, and animal kingdoms share a highly conserved domain containing invariant histidine and aspartic acid residues separated by four less conserved residues in an HX4D configuration. We investigated the role of the invariant histidine residue in acyltransferase catalysis by site-directed mutagenesis of two representative members of this family, the sn-glycerol-3-phosphate acyltransferase (PlsB) and the bifunctional 2-acyl-glycerophosphoethanolamine acyltransferase/acyl-acyl carrier protein synthetase (Aas) ofEscherichia coli. Both the PlsB[H306A] and Aas[H36A] mutants lacked acyltransferase activity. However, the Aas[H36A] mutant retained significant acyl-acyl carrier protein synthetase activity, illustrating that the lack of acyltransferase activity was specifically associated with the H36A substitution. The invariant aspartic acid residue in the HX4D pattern was also important. The substitution of aspartic acid 311 with glutamic acid in PlsB resulted in an enzyme with significantly reduced catalytic activity. Substitution of an alanine at this position eliminated acyltransferase activity; however, the PlsB[D311A] mutant protein did not assemble into the membrane, indicating that aspartic acid 311 is also important for the proper folding and membrane insertion of the acyltransferases. These data are consistent with a mechanism for glycerolipid acyltransferase catalysis where the invariant histidine functions as a general base to deprotonate the hydroxyl moiety of the acyl acceptor.

Biochemical Characterization of Chloromethane Emission from the Wood-Rotting Fungus Phellinus pomaceus

1998 ◽  
Vol 64 (8) ◽  
pp. 2831-2835 ◽  
Author(s):  
Deepti Saxena ◽  
Saleh Aouad ◽  
Jihad Attieh ◽  
Hargurdeep S. Saini
Keyword(s):  
Atmospheric Chemistry ◽  
Biochemical Characterization ◽  
Active Form ◽  
Methyl Chloride ◽  
Bound State ◽  
Ph Optimum ◽  
Methyl Donors ◽  
Membrane Bound

ABSTRACT Many wood-rotting fungi, including Phellinus pomaceus, produce chloromethane (CH3Cl). P. pomaceus can be cultured in undisturbed glucose mycological peptone liquid medium to produce high amounts of CH3Cl. The biosynthesis of CH3Cl is catalyzed by a methyl chloride transferase (MCT), which appears to be membrane bound. The enzyme is labile upon removal from its natural location and upon storage at low temperature in its bound state. Various detergents failed to solubilize the enzyme in active form, and hence it was characterized by using a membrane fraction. The enzyme had a sharp pH optimum between 7 and 7.2. Its apparent Km for Cl− (ca. 300 mM) was much higher than that for I− (250 μM) or Br− (11 mM). A comparison of theseKm values to the relative in vivo methylation rates for different halides suggests that the realKm for Cl− may be much lower, but the calculated value is high because the CH3Cl produced is used immediately in a coupled reaction. Among various methyl donors tested, S-adenosyl-l-methionine (SAM) was the only one that supported significant methylation by MCT. The reaction was inhibited by S-adenosyl-l-homocysteine, an inhibitor of SAM-dependent methylation, suggesting that SAM is the natural methyl donor. These findings advance our comprehension of a poorly understood metabolic sector at the origin of biogenic emissions of halomethanes, which play an important role in atmospheric chemistry.

Enoyl-Acyl Carrier Protein Reductase (InhA): A REMARKABLE TARGET TO EXTERMINATE TUBERCULOSIS

2020 ◽  
Vol 18 ◽  
Author(s):  
Surabhi Jain ◽  
Smriti Sharma ◽  
Dhrubo Jyoti Sen ◽  
Saurabh S Pandya
Keyword(s):  
Target Gene ◽  
Acyl Carrier Protein ◽  
Molar Concentration ◽  
Carrier Protein ◽  
Important Target ◽  
Mutant Strains ◽  
Cause Of Failure ◽  
Direct Inhibitors ◽  
Fas Ii

: Tuberculosis, epidemic that needs new molecules with high potency and minimum side effects. In same respect, this review emphases on important target enoyl-acyl carrier protein reductase or INHA crucial in completion of FAS II cycle. INHA retain its fame since inception of drug Isoniazid as inhibitors have long residence time hence good activity. One of the cause of failure of conventional drugs is resistance towards activating or target gene. Here, we propose direct inhibitors that doesn’t need prior activation by Kat G. Some of the categories are aryl amide, Piperazine, Thiadiazole, Benzamide etc. that are specifically active against INHA along with their Structure activity relationship. Many of them are efficient in micro molar concentration whereas Pyrazole carboxamide are active in nano molar concentration and derivative of 4-hydroxy pyridones was effective in vivo. Natural products are also in way to combat tuberculosis. Furthermore, from available proteins of wild and mutant strains new leads can be designed sucessfully by utilizing information of cocrystallized ligand.

scholarly journals Antimycobacterial action of thiolactomycin: an inhibitor of fatty acid and mycolic acid synthesis.

1996 ◽  
Vol 40 (12) ◽  
pp. 2813-2819 ◽  
Author(s):  
R A Slayden ◽  
R E Lee ◽  
J W Armour ◽  
A M Cooper ◽  
I M Orme ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthase ◽  
Acyl Carrier Protein ◽  
Mycolic Acid ◽  
Carrier Protein ◽  
Type I ◽  
Dependent Manner ◽  
Fas Ii

Thiolactomycin (TLM) possesses in vivo antimycobacterial activity against the saprophytic strain Mycobacterium smegmatis mc2155 and the virulent strain M. tuberculosis Erdman, resulting in complete inhibition of growth on solid media at 75 and 25 micrograms/ml, respectively. Use of an in vitro murine macrophage model also demonstrated the killing of viable intracellular M. tuberculosis in a dose-dependent manner. Through the use of in vivo [1,2-14C]acetate labeling of M. smegmatis, TLM was shown to inhibit the synthesis of both fatty acids and mycolic acids. However, synthesis of the shorter-chain alpha'-mycolates of M. smegmatis was not inhibited by TLM, whereas synthesis of the characteristic longer-chain alpha-mycolates and epoxymycolates was almost completely inhibited at 75 micrograms/ml. The use of M. smegmatis cell extracts demonstrated that TLM specifically inhibited the mycobacterial acyl carrier protein-dependent type II fatty acid synthase (FAS-II) but not the multifunctional type I fatty acid synthase (FAS-I). In addition, selective inhibition of long-chain mycolate synthesis by TLM was demonstrated in a dose-response manner in purified, cell wall-containing extracts of M. smegmatis cells. The in vivo and in vitro data and knowledge of the mechanism of TLM resistance in Escherichia coli suggest that two distinct TLM targets exist in mycobacteria, the beta-ketoacyl-acyl carrier protein synthases involved in FAS-II and the elongation steps leading to the synthesis of the alpha-mycolates and oxygenated mycolates. The efficacy of TLM against M. smegmatis and M. tuberculosis provides the prospects of identifying fatty acid and mycolic acid biosynthetic genes and revealing a novel range of chemotherapeutic agents directed against M. tuberculosis.

Mössbauer Studies of the Formation and Reactivity of a Quasi-Stable Peroxo Intermediate of Stearoyl-Acyl Carrier Protein Δ9-Desaturase†

Biochemistry ◽  
1999 ◽  
Vol 38 (38) ◽  
pp. 12197-12204 ◽  
Author(s):  
John A. Broadwater ◽  
Catalina Achim ◽  
Eckard Münck ◽  
Brian G. Fox
Keyword(s):  
Acyl Carrier Protein ◽  
Carrier Protein ◽  
Mössbauer Studies ◽  
Δ9 Desaturase ◽  
Peroxo Intermediate

scholarly journals Rapid in Vivo Acylation of Acyl Carrier Protein with Exogenous Fatty Acids in Spirodela oligorrhiza

1989 ◽  
Vol 89 (2) ◽  
pp. 707-711 ◽  
Author(s):  
Autar K. Mattoo ◽  
Franklin E. Callahan ◽  
Roshni A. Mehta ◽  
John B. Ohlrogge
Keyword(s):  
Fatty Acids ◽  
Acyl Carrier Protein ◽  
Carrier Protein ◽  
Spirodela Oligorrhiza
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