Publications

• Structural, enzymatic, and genetic studies of beta-ketoacyl-acyl carrier protein synthases I and II of Escherichia coli.

  Garwin J.L., Klages A.L., Cronan J.E. Jr.

  Beta-Ketoacyl-acyl carrier protein synthases I and II of Escherichia coli were purified and characterized. Synthase I was shown to have a molecular weight of 80,000 +/-5,000 and to be composed of two similarly sized subunits. Synthase II had a molecular weight of 85,000 +/-5,000 and also was appar ... >> More

  Beta-Ketoacyl-acyl carrier protein synthases I and II of Escherichia coli were purified and characterized. Synthase I was shown to have a molecular weight of 80,000 +/-5,000 and to be composed of two similarly sized subunits. Synthase II had a molecular weight of 85,000 +/-5,000 and also was apparently homodimeric. Gel electrophoresis of partial proteolytic digests demonstrated that synthases I and II share few if any common peptides. Synthases I and II also were shown to be unrelated by immunological criteria. An improved assay for beta-ketoacyl-acyl carrier protein synthase activity gave kinetic parameters for synthases I and II at both 27 degrees C and 37 degrees C using five long chain acyl-acyl carrier protein substrates. The properties of synthase II are consistent with the proposed role of this enzyme in the modulation of fatty acid synthesis by temperature. fabF mutants of E. coli lack synthase II. The fabF locus was mapped at min 24.5 of the E. coli genetic map and the clockwise map order was found to be pyrC, fabD, fabF, purB. << Less

  J Biol Chem 255:11949-11956(1980) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Cloning, expression, and characterization of the human mitochondrial beta-ketoacyl synthase. Complementation of the yeast CEM1 knock-out strain.

  Zhang L., Joshi A.K., Hofmann J., Schweizer E., Smith S.

  A human beta-ketoacyl synthase implicated in a mitochondrial pathway for fatty acid synthesis has been identified, cloned, expressed, and characterized. Sequence analysis indicates that the protein is more closely related to freestanding counterparts found in prokaryotes and chloroplasts than it i ... >> More

  A human beta-ketoacyl synthase implicated in a mitochondrial pathway for fatty acid synthesis has been identified, cloned, expressed, and characterized. Sequence analysis indicates that the protein is more closely related to freestanding counterparts found in prokaryotes and chloroplasts than it is to the beta-ketoacyl synthase domain of the human cytosolic fatty acid synthase. The full-length nuclear-encoded 459-residue protein includes an N-terminal sequence element of approximately 38 residues that functions as a mitochondrial targeting sequence. The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial beta-ketoacyl synthase and exhibits lowered lipoic acid levels. To date, four components of a putative type II mitochondrial fatty acid synthase pathway have been identified in humans: acyl carrier protein, malonyl transferase, beta-ketoacyl synthase, and enoyl reductase. The substrate specificity and complementation data for the beta-ketoacyl synthase suggest that, as in plants and fungi, in humans this pathway may play an important role in the generation of octanoyl-acyl carrier protein, the lipoic acid precursor, as well as longer chain fatty acids that are required for optimal mitochondrial function. << Less

  J. Biol. Chem. 280:12422-12429(2005) [PubMed] [EuropePMC]

  This publication is cited by 6 other entries.

• Studies on the mechanism of fatty acid synthesis. XVI. Preparation and general properties of acyl-malonyl acyl carrier protein-condensing enzyme from Escherichia coli.

  Toomey R.E., Wakil S.J.

  J Biol Chem 241:1159-1165(1966) [PubMed] [EuropePMC]

• Multiple forms of beta-ketoacyl-acyl carrier protein synthetase in Escherichia coli.

  D'Agnolo G., Rosenfeld I.S., Vagelos P.R.

  Two forms of beta-ketoacyl-acyl carrier protein (ACP) synthetase (designated I and II) have been identified in extracts of Escherichia coli. Synthetase I corresponds to the condensing enzyme that was studied earlier (GREENSPAN, M.D., ALBERTS, A.W., and VAGELOS, P.R. (1969) J. Biol. Chem. 244, 6477 ... >> More

  Two forms of beta-ketoacyl-acyl carrier protein (ACP) synthetase (designated I and II) have been identified in extracts of Escherichia coli. Synthetase I corresponds to the condensing enzyme that was studied earlier (GREENSPAN, M.D., ALBERTS, A.W., and VAGELOS, P.R. (1969) J. Biol. Chem. 244, 6477-6485); synthetase II represents a new form of the enzyme. Synthetase II was isolated as a homogeneous protein. It differs from synthetase I in having a higher molecular weight (76,999 versus 66,000), a lower pH optimum (5.5 to 6.1 versus 7.2), and a greater resistance to denaturation by heat. Synthetase II is similar to synthetase I in that both are inactivated by iodoacetamide, and prior incubation of the enzymes with fatty acyl thioesters prevents the inhibitory effect of iodoacetamide. Both also react with a fatty acyl thioester to form an acyl-enzyme intermediate, and the latter reacts with malonyl-ACP to form a beta-ketoacyl thioester. Specificity studies indicated that synthetase II, like synthetase I, has similar affinities with saturated and cis unsaturated fatty acyl thioesters of ACP that are intermediates in the synthesis of saturated and unsaturated fatty acids, respectively. The two synthetases differ only with respect to reactivity with palmitoleyl thioesters: synthetase II has a lower Km and higher Vmax than synthetase I with palmitoleyl-ACP. This finding suggests that synthetase II functions specifically in the elongation of palmitoleyl-ACP to form cis-vaccenyl-ACP. An investigation of synthetases I and II in two classes of unsaturated fatty acid auxotrophs revealed that synthetase I is absent in one class, fabB. Addition of wild type synthetase I to fabB fatty acid synthetase, which synthesizes only saturated fatty acids, permitted this fatty acid synthetase to synthesize unsaturated fatty acids. These experiments indicate that synthetase I plays a critical role in the synthesis of unsaturated fatty acids. << Less

  J Biol Chem 250:5289-5294(1975) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.