101
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Beigneux AP, Vergnes L, Qiao X, Quatela S, Davis R, Watkins SM, Coleman RA, Walzem RL, Philips M, Reue K, Young SG. Agpat6--a novel lipid biosynthetic gene required for triacylglycerol production in mammary epithelium. J Lipid Res 2006; 47:734-44. [PMID: 16449762 PMCID: PMC3196597 DOI: 10.1194/jlr.m500556-jlr200] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In analyzing the sequence tags for mutant mouse embryonic stem (ES) cell lines in BayGenomics (a mouse gene-trapping resource), we identified a novel gene, 1-acylglycerol-3-phosphate O-acyltransferase (Agpat6), with sequence similarities to previously characterized glycerolipid acyltransferases. Agpat6's closest family member is another novel gene that we have provisionally designated Agpat8. Both Agpat6 and Agpat8 are conserved from plants, nematodes, and flies to mammals. AGPAT6, which is predicted to contain multiple membrane-spanning helices, is found exclusively within the endoplasmic reticulum (ER) in mammalian cells. To gain insights into the in vivo importance of Agpat6, we used the Agpat6 ES cell line from BayGenomics to create Agpat6-deficient (Agpat6-/-) mice. Agpat6-/- mice lacked full-length Agpat6 transcripts, as judged by northern blots. One of the most striking phenotypes of Agpat6-/- mice was a defect in lactation. Pups nursed by Agpat6-/- mothers die perinatally. Normally, Agpat6 is expressed at high levels in the mammary epithelium of breast tissue, but not in the surrounding adipose tissue. Histological studies revealed that the aveoli and ducts of Agpat6-/- lactating mammary glands were underdeveloped, and there was a dramatic decrease in the size and number of lipid droplets within mammary epithelial cells and ducts. Also, the milk from Agpat6-/- mice was markedly depleted in diacylglycerols and triacylglycerols. Thus, we identified a novel glycerolipid acyltransferase of the ER, AGPAT6, which is crucial for the production of milk fat by the mammary gland.
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Affiliation(s)
- Anne P Beigneux
- Division of Cardiology, Department of Internal Medicine, University of California, Los Angeles, CA 90095, USA.
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102
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Bonham L, Leung DW, White T, Hollenback D, Klein P, Tulinsky J, Coon M, de Vries P, Singer JW. Lysophosphatidic acid acyltransferase-beta: a novel target for induction of tumour cell apoptosis. Expert Opin Ther Targets 2005; 7:643-61. [PMID: 14498826 DOI: 10.1517/14728222.7.5.643] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Phosphatidic acid (PA) is a component of cellular membranes that is also a mediator of certain cell signalling functions associated with oncogenesis. These include ras/raf/Erk and Akt/mTor [1-3]. The authors have investigated whether it would be possible to interrupt these known oncogenic pathways through the inhibition of lysophosphatidic acid acyltransferase (LPAAT), an enzyme that catalyses the biosynthesis of PA. The expression and activity of the LPAAT-beta isoform are elevated in human tumours, and the respective gene displays transforming capacity when overexpressed in vitro. Inhibition by either genetic means or by isoform-specific small molecules results in a block to cell signalling pathways and apoptosis. Furthermore, the small-molecule inhibitors of LPAAT-beta are not cytotoxic to a number of normal cell types, including primary bone marrow progenitors, indicating a differential dependence of tumour cells on LPAAT-beta function. These discoveries indicate that LPAAT-beta represents a potential novel cancer therapy target.
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MESH Headings
- Acylation/drug effects
- Acyltransferases/antagonists & inhibitors
- Acyltransferases/genetics
- Acyltransferases/physiology
- Animals
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Apoptosis/drug effects
- Carcinoma, Lewis Lung/drug therapy
- Cell Division/drug effects
- Cell Division/physiology
- Cell Line, Tumor/drug effects
- Cell Transformation, Neoplastic
- Chromosomes, Human, Pair 9/genetics
- Drug Design
- Drug Evaluation, Preclinical
- Genes, ras
- Humans
- Hydrocarbons, Halogenated/pharmacology
- Hydrocarbons, Halogenated/therapeutic use
- Lung Neoplasms/drug therapy
- Mice
- Neoplasm Proteins/antagonists & inhibitors
- Neoplasm Proteins/physiology
- Neoplasms/drug therapy
- Neoplasms/pathology
- Phosphatidic Acids/physiology
- Protein Conformation
- Protein Processing, Post-Translational/drug effects
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Triazines/pharmacology
- Triazines/therapeutic use
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Affiliation(s)
- Lynn Bonham
- Cell Therapeutics, Inc., 201 Elliott Avenue West, Suite 400, Seattle, WA 98119, USA.
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103
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Gao JL, Weissenmayer B, Taylor AM, Thomas-Oates J, López-Lara IM, Geiger O. Identification of a gene required for the formation of lyso-ornithine lipid, an intermediate in the biosynthesis of ornithine-containing lipids. Mol Microbiol 2004; 53:1757-70. [PMID: 15341653 DOI: 10.1111/j.1365-2958.2004.04240.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Under phosphate-limiting conditions, some bacteria replace their membrane phospholipids by lipids not containing any phosphorus. One of these phosphorus-free lipids is an ornithine-containing lipid (OL) that is widespread among eubacteria. In earlier work, we had identified a gene (olsA) required for OL biosynthesis that probably encodes an O-acyltransferase using acyl-acyl carrier protein (acyl-AcpP) as an acyl donor and that converts lyso-ornithine lipid into OL. We now report on a second gene (olsB) required for OL biosynthesis that is needed for the incorporation of radiolabelled ornithine into OL. Overexpression of OlsB in an olsA-deficient mutant of Sinorhizobium (Rhizobium) meliloti leads to the transient accumulation of lyso-ornithine lipid, the biosynthetic intermediate of OL biosynthesis. Overexpression of OlsB in Escherichia coli is sufficient to cause the in vivo formation of lyso-ornithine lipid in this organism and is the cause for a 3-hydroxyacyl-AcpP-dependent acyltransferase activity forming lyso-ornithine lipid from ornithine. These results demonstrate that OlsB is required for the first step of OL biosynthesis, in which ornithine is N-acylated with a 3-hydroxy-fatty acyl residue in order to obtain lyso-ornithine lipid. OL formation in a wild-type S. meliloti is increased upon growth under phosphate-limiting conditions. Expression of OlsB from a broad host range vector leads to the constitutive formation of relatively high amounts of OL (12-14% of total membrane lipids) independently of whether strains are grown in the presence of low or high concentrations of phosphate, suggesting that in S. meliloti the formation of OlsB is usually limiting for the amount of OL formed in this organism. Open reading frames homologous to OlsA and OlsB were identified in many eubacteria and although in S. meliloti the olsB and olsA gene are 14 kb apart, in numerous other bacteria they form an operon.
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Affiliation(s)
- Jun-Lian Gao
- Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, CP62210, Mexico
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104
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Lu B, Kelher MR, Lee DP, Lewin TM, Coleman RA, Choy PC, Hatch GM. Complex expression pattern of the Barth syndrome gene product tafazzin in human cell lines and murine tissues. Biochem Cell Biol 2004; 82:569-76. [PMID: 15499385 DOI: 10.1139/o04-055] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tafazzins, a group of proteins that are defective in patients with Barth syndrome, are produced by alternate splicing of the gene G4.5 or TAZ. RT-PCR and transcription-coupled in vitro translation analysis were undertaken to determine the expression of alternatively spliced TAZ mRNA in mouse tissues and human cell lines. Only two tafazzin transcripts, both lacking exon 5, were expressed in murine tissues, whereas four tafazzin transcripts, all lacking exon 5, were observed in human umbilical vein vascular endothelial cells and U937 human monoblasts indicating a species-specific difference in the expression of TAZ mRNAs in mouse and humans. Only TAZ lacking exon 5 was expressed in murine heart. Differentiation of U937 human monoblasts into macrophages did not alter expression of the tafazzin transcripts indicating that TAZ expression is independent of monocyte differentiation. Cloning and in vitro expression of both murine and human tafazzin cDNA revealed two prominent protein bands that corresponded to the expected sizes of alternative translation. A novel fifth motif, identified as critical for the glycerolphosphate acyltransferase family, was observed in human tafazzin. The presence of a mutation in this region in Barth syndrome patients indicates that this motif is essential for tafazzin function.Key words: cardiolipin, murine, heart, Barth Syndrome, phospholipid, acyltransferase, tafazzin.
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Affiliation(s)
- Biao Lu
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3E 0T6, Canada
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105
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Mahato S, De D, Dutta D, Kundu M, Bhattacharya S, Schiavone MT, Bhattacharya SK. Potential use of sugar binding proteins in reactors for regeneration of CO2 fixation acceptor D-Ribulose-1,5-bisphosphate. Microb Cell Fact 2004; 3:7. [PMID: 15175111 PMCID: PMC421735 DOI: 10.1186/1475-2859-3-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2004] [Accepted: 06/02/2004] [Indexed: 12/02/2022] Open
Abstract
Sugar binding proteins and binders of intermediate sugar metabolites derived from microbes are increasingly being used as reagents in new and expanding areas of biotechnology. The fixation of carbon dioxide at emission source has recently emerged as a technology with potentially significant implications for environmental biotechnology. Carbon dioxide is fixed onto a five carbon sugar D-ribulose-1,5-bisphosphate. We present a review of enzymatic and non-enzymatic binding proteins, for 3-phosphoglycerate (3PGA), 3-phosphoglyceraldehyde (3PGAL), dihydroxyacetone phosphate (DHAP), xylulose-5-phosphate (X5P) and ribulose-1,5-bisphosphate (RuBP) which could be potentially used in reactors regenerating RuBP from 3PGA. A series of reactors combined in a linear fashion has been previously shown to convert 3-PGA, (the product of fixed CO2 on RuBP as starting material) into RuBP (Bhattacharya et al., 2004; Bhattacharya, 2001). This was the basis for designing reactors harboring enzyme complexes/mixtures instead of linear combination of single-enzyme reactors for conversion of 3PGA into RuBP. Specific sugars in such enzyme-complex harboring reactors requires removal at key steps and fed to different reactors necessitating reversible sugar binders. In this review we present an account of existing microbial sugar binding proteins and their potential utility in these operations.
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Affiliation(s)
- Sourav Mahato
- Department of Biotechnology, Haldia Institute of Technology, Haldia, West Bengal, India
| | - Debojyoti De
- Department of Biotechnology, Haldia Institute of Technology, Haldia, West Bengal, India
| | - Debajyoti Dutta
- Department of Biotechnology, Haldia Institute of Technology, Haldia, West Bengal, India
| | - Moloy Kundu
- Department of Biotechnology, Haldia Institute of Technology, Haldia, West Bengal, India
| | - Sumana Bhattacharya
- Environmental Biotechnology Division, ABRD Company LLC, 1555 Wood Road, Cleveland, Ohio, 44121, USA
| | - Marc T Schiavone
- Environmental Biotechnology Division, ABRD Company LLC, 1555 Wood Road, Cleveland, Ohio, 44121, USA
| | - Sanjoy K Bhattacharya
- Department of Ophthalmic Research, Cleveland Clinic Foundation, Area I31, 9500 Euclid Avenue, Cleveland, Ohio, 44195, USA
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106
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Lindén D, William-Olsson L, Rhedin M, Asztély AK, Clapham JC, Schreyer S. Overexpression of mitochondrial GPAT in rat hepatocytes leads to decreased fatty acid oxidation and increased glycerolipid biosynthesis. J Lipid Res 2004; 45:1279-88. [PMID: 15102885 DOI: 10.1194/jlr.m400010-jlr200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycerol-3-phosphate acyltransferase (GPAT) catalyses the first committed step in glycerolipid biosynthesis. The mitochondrial isoform (mtGPAT) is mainly expressed in liver, where it is highly regulated, indicating that mtGPAT may have a unique role in hepatic fatty acid metabolism. Because both mtGPAT and carnitine palmitoyl transferase-1 are located on the outer mitochondrial membrane, we hypothesized that mtGPAT directs fatty acyl-CoA away from beta-oxidation and toward glycerolipid synthesis. Adenoviral-mediated overexpression of murine mtGPAT in primary cultures of rat hepatocytes increased mtGPAT activity 2.7-fold with no compensatory effect on microsomal GPAT activity. MtGPAT overexpression resulted in a dramatic 80% reduction in fatty acid oxidation and a significant increase in hepatic diacylglycerol and phospholipid biosynthesis. Following lipid loading of the cells, intracellular triacylglycerol biosynthesis was also induced by mtGPAT overexpression. Changing an invariant aspartic acid residue to a glycine [D235G] in mtGPAT resulted in an inactive enzyme, which helps define the active site required for mammalian mtGPAT function. To determine if obesity increases hepatic mtGPAT activity, two models of rodent obesity were examined and shown to have >2-fold increased enzyme activity. Overall, these results support the concept that increased hepatic mtGPAT activity associated with obesity positively contributes to lipid disorders by reducing oxidative processes and promoting de novo glycerolipid synthesis.
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107
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Kim HU, Huang AHC. Plastid lysophosphatidyl acyltransferase is essential for embryo development in Arabidopsis. PLANT PHYSIOLOGY 2004; 134:1206-16. [PMID: 14976237 PMCID: PMC389945 DOI: 10.1104/pp.103.035832] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Revised: 11/29/2003] [Accepted: 12/09/2003] [Indexed: 05/18/2023]
Abstract
Lysophosphatidyl acyltransferase (LPAAT) is a pivotal enzyme controlling the metabolic flow of lysophosphatidic acid into different phosphatidic acids in diverse tissues. A search of the Arabidopsis genome database revealed five genes that could encode LPAAT-like proteins. We identified one of them, LPAAT1, to be the lone gene that encodes the plastid LPAAT. LPAAT1 could functionally complement a bacterial mutant that has defective LPAAT. Bacteria transformed with LPAAT1 produced LPAAT that had in vitro enzyme activity much higher on 16:0-coenzyme A than on 18:1-coenzyme A in the presence of 18:1-lysophosphatidic acid. LPAAT1 transcript was present in diverse organs, with the highest level in green leaves. A mutant having a T-DNA inserted into LPAAT1 was identified. The heterozygous mutant has no overt phenotype, and its leaf acyl composition is similar to that of the wild type. Selfing of a heterozygous mutant produced normal-sized and shrunken seeds in the Mendelian ratio of 3:1, and the shrunken seeds could not germinate. The shrunken seeds apparently were homozygous of the T-DNA-inserted LPAAT1, and development of the embryo within them was arrested at the heart-torpedo stage. This embryo lethality could be rescued by transformation of the heterozygous mutant with a 35S:LPAAT1 construct. The current findings of embryo death in the homozygous knockout mutant of the plastid LPAAT contrasts with earlier findings of a normal phenotype in the homozygous mutant deficient of the plastid glycerol-3-phosphate acyltransferase; both mutations block the synthesis of plastid phosphatidic acid. Reasons for the discrepancy between the contrasting phenotypes of the two mutants are discussed.
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Affiliation(s)
- Hyun Uk Kim
- Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
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108
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Li D, Yu L, Wu H, Shan Y, Guo J, Dang Y, Wei Y, Zhao S. Cloning and identification of the human LPAAT-zeta gene, a novel member of the lysophosphatidic acid acyltransferase family. J Hum Genet 2003; 48:438-442. [PMID: 12938015 DOI: 10.1007/s10038-003-0045-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2003] [Accepted: 05/26/2003] [Indexed: 11/24/2022]
Abstract
Lysophosphatidic acid (LPA) is a naturally occurring component of phospholipid and plays a critical role in the regulation of many physiological and pathophysiological processes including cell growth, survival, and pro-angiogenesis. LPA is converted to phosphatidic acid by the action of lysophosphatidic acid acyltransferase (LPAAT). Five members of the LPAAT gene family have been detected in humans to date. Here, we report the identification of a novel LPAAT member, which is designated as LPAAT-zeta. LPAAT-zeta was predicted to encode a protein consisting of 456 amino acid residues with a signal peptide sequence and the acyltransferase domain. Northern blot analysis showed that LPAAT-zeta was ubiquitously expressed in all 16 human tissues examined, with levels in the skeletal muscle, heart, and testis being relatively high and in the lung being relatively low. The human LPAAT-zeta gene consisted of 13 exons and is positioned at chromosome 8p11.21.
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Affiliation(s)
- Dan Li
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, 200433, Shanghai, P.R. China
| | - Long Yu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, 200433, Shanghai, P.R. China.
- Institute of Genetics, Fudan University, 220 Handan Road, 200433, Shanghai, P.R. China.
| | - Hai Wu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, 200433, Shanghai, P.R. China
| | - Yuxi Shan
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, 200433, Shanghai, P.R. China
| | - Jinhu Guo
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, 200433, Shanghai, P.R. China
| | - Yongjun Dang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, 200433, Shanghai, P.R. China
| | - Youheng Wei
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, 200433, Shanghai, P.R. China
| | - Shouyuan Zhao
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, 200433, Shanghai, P.R. China
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109
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Abstract
Phospholipids play multiple roles in bacterial cells. These are the establishment of the permeability barrier, provision of the environment for many enzyme and transporter proteins, and they influence membrane-related processes such as protein export and DNA replication. The lipid synthetic pathway also provides precursors for protein modification and for the synthesis of other molecules. This review concentrates on the phospholipid synthetic pathway and discusses recent data on the synthesis and function of phospholipids mainly in the bacterium Escherichia coli.
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Affiliation(s)
- John E Cronan
- Department of Microbiology, University of Illinois, Urbana, Illinois 61801, USA.
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110
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Matsumoto K, Matsusaki H, Taguchi S, Seki M, Doi Y. Cloning and characterization of the Pseudomonas sp. 61-3 phaG gene involved in polyhydroxyalkanoate biosynthesis. Biomacromolecules 2002; 2:142-7. [PMID: 11749165 DOI: 10.1021/bm005604+] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pseudomonas sp. 61-3 produces a blend of poly(3-hydroxybutyrate) [P(3HB)] homopolymer and poly(3-hydroxybutyrate-co-3-hydroxyalkanoates) [P(3HB-co-3HA)] random copolymer consisting of monomeric units of 4-12 carbon atoms from sugars. The phaG(Ps) gene encoding (R)-3-hydroxyacyl-acyl carrier protein coenzyme A transferase was cloned from this strain, and homologous expression of this gene under the control of the lac or the native promoter was investigated. Additional copies of the phaG(Ps) gene in Pseudomonas sp. 61-3 led to an increase in both the polyhydroxyalkanoate (PHA) content in the cells and the fraction of medium-chain-length 3HA units in PHA. Disruption of the chromosomal phaG(Ps) gene resulted in an increase in the fraction of the 3HB unit in PHA. The site-directed mutagenesis of the phaG(Ps) gene was carried out to investigate the role of a HX(4)D motif which has been proposed to be related to PhaG activity.
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Affiliation(s)
- K Matsumoto
- Polymer Chemistry Laboratory, RIKEN Institute, 2-1, Hirosawa, Wako-shi, Saitama 350-0198, Japan
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111
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Hammond LE, Gallagher PA, Wang S, Hiller S, Kluckman KD, Posey-Marcos EL, Maeda N, Coleman RA. Mitochondrial glycerol-3-phosphate acyltransferase-deficient mice have reduced weight and liver triacylglycerol content and altered glycerolipid fatty acid composition. Mol Cell Biol 2002; 22:8204-14. [PMID: 12417724 PMCID: PMC134068 DOI: 10.1128/mcb.22.23.8204-8214.2002] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microsomal and mitochondrial isoforms of glycerol-3-phosphate acyltransferase (GPAT; E.C. 2.3.1.15) catalyze the committed step in glycerolipid synthesis. The mitochondrial isoform, mtGPAT, was believed to control the positioning of saturated fatty acids at the sn-1 position of phospholipids, and nutritional, hormonal, and overexpression studies suggested that mtGPAT activity is important for the synthesis of triacylglycerol. To determine whether these purported functions were true, we constructed mice deficient in mtGPAT. mtGPAT(-/-) mice weighed less than controls and had reduced gonadal fat pad weights and lower hepatic triacylglycerol content, plasma triacylglycerol, and very low density lipoprotein triacylglycerol secretion. As predicted, in mtGPAT(-/-) liver, the palmitate content was lower in triacylglycerol, phosphatidylcholine, and phosphatidylethanolamine. Positional analysis revealed that mtGPAT(-/-) liver phosphatidylethanolamine and phosphatidylcholine had about 21% less palmitate in the sn-1 position and 36 and 40%, respectively, more arachidonate in the sn-2 position. These data confirm the important role of mtGPAT in the synthesis of triacylglycerol, in the fatty acid content of triacylglycerol and cholesterol esters, and in the positioning of specific fatty acids, particularly palmitate and arachidonate, in phospholipids. The increase in arachidonate may be functionally significant in terms of eicosanoid production.
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Affiliation(s)
- Linda E Hammond
- Department of Nutrition. Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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112
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Slabas AR, Kroon JTM, Scheirer TP, Gilroy JS, Hayman M, Rice DW, Turnbull AP, Rafferty JB, Fawcett T, Simon WJ. Squash glycerol-3-phosphate (1)-acyltransferase. Alteration of substrate selectivity and identification of arginine and lysine residues important in catalytic activity. J Biol Chem 2002; 277:43918-23. [PMID: 12205087 DOI: 10.1074/jbc.m206429200] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycerol-3-phosphate 1-acyltransferase is a soluble chloroplast enzyme involved in glycerol-lipid biosynthesis associated with chilling resistance in plants (). Resistance is associated with higher selectivity for unsaturated acyl substrates over saturated ones. In vitro substrate selectivity assays performed under physiologically relevant conditions have been established that discriminate between selective and non-selective forms of the enzyme. A mutation, L261F, in the squash protein converts it from a non-selective enzyme into a selective one. The mutation lies within 10 A of the predicted acyl binding site and results in a higher K(m) for 16:0 acyl carrier protein (ACP). Site-directed mutagenesis was used to determine the importance of four residues, Arg(235), Arg(237), Lys(193), and His(194), implicated to be involved in binding of the phosphate group of glycerol 3-phosphate to the enzyme. All the proteins were highly homologous in structure to the wild type enzyme. Mutations in Arg(235), Arg(237), and Lys(193) resulted in inactive enzyme, while His(194) had reduced catalytic activity. The mutant proteins retained the ability to bind stoichiometric quantities of acyl-ACPs supporting the potential role of these residues in glycerol 3-phosphate binding.
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Affiliation(s)
- Antoni R Slabas
- Department of Biological and Biomedical Sciences, University of Durham, Science Laboratories, South Road, United Kingdom.
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113
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Weissenmayer B, Gao JL, López-Lara IM, Geiger O. Identification of a gene required for the biosynthesis of ornithine-derived lipids. Mol Microbiol 2002; 45:721-33. [PMID: 12139618 DOI: 10.1046/j.1365-2958.2002.03043.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Phospholipids are the membrane-forming constituents in all living organisms. In addition to phosphorus-containing lipids, the membranes of numerous bacteria contain significant amounts of phosphorus-free polar lipids, often derived from amino acids. Although lipids derived from the amino acid ornithine are widespread among bacteria, their biosynthesis is unknown. Here, we describe the isolation of mutants of Sinorhizobium meliloti deficient in the biosynthesis of ornithine-derived lipids (OL). Complementation of such mutants with a sinorhi-zobial cosmid gene bank, subcloning of the complementing fragment and sequencing of the subclone led to the identification of a gene (olsA) coding for a presumptive acyltransferase. Amplification of this gene and its expression in OL-deficient mutant backgrounds of S. meliloti demonstrates that it is required for OL biosynthesis. An OL-deficient mutant of S. meliloti disrupted in olsA shows wild type-like growth behaviour and is capable of inducing nitrogen-fixing nodules on legume hosts. A lyso-ornithine lipid-dependent acyltransferase activity forming OL requires acyl-AcpP as the acyl donor and expression of the olsA gene.
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Affiliation(s)
- Barbara Weissenmayer
- Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Cuernavaca, Morelos
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114
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Gonzalez-Baro MR, Granger DA, Coleman RA. Mitochondrial glycerol phosphate acyltransferase contains two transmembrane domains with the active site in the N-terminal domain facing the cytosol. J Biol Chem 2001; 276:43182-8. [PMID: 11557771 DOI: 10.1074/jbc.m107885200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The topography of mitochondrial glycerol-3-phosphate acyltransferase (GPAT) was determined using rat liver mitochondria and mutagenized recombinant rat GPAT (828 aa (amino acids)) expressed in CHO cells. Hydrophobicity analysis of GPAT predicts two transmembrane domains (TMDs), residues 472-493 and 576-592. Residues 224-323 correspond to the active site of the enzyme, which is believed to lie on the cytosolic face of the outer mitochondrial membrane. Protease treatment of rat liver mitochondria revealed that GPAT has a membrane-protected segment of 14 kDa that could correspond to the mass of the two predicted TMDs plus a loop between aa 494 and 575. Recombinant GPAT constructs containing tagged epitopes were transiently expressed in Chinese hamster ovary cells and immunolocalized. Both the C and N termini epitope tags could be detected after selective permeabilization of only the plasma membrane, indicating that both termini face the cytosol. A 6-8-fold increase in GPAT-specific activity in the transfected cells confirmed correct protein folding and orientation. When the C terminus and loop-tagged GPAT construct was immunoassayed, the epitope at the C terminus could be detected when the plasma membrane was permeabilized, but loop-epitope accessibility required disruption of the outer mitochondrial membrane. Similar results were observed when GPAT was truncated before the second TMD, again consistent with an orientation in which the loop faces the mitochondrial intermembrane space. Although protease digestion of the HA-tagged loop resulted in preservation of a 14-kDa fragment, consistent with a membrane protected loop domain, neither the truncated nor loop-tagged enzymes conferred GPAT activity when overexpressed, suggesting that the loop plays a critical structural or regulatory role for GPAT function. Based on these data, we propose a GPAT topography model with two transmembrane domains in which both the N (aa 1-471) and C (aa 593-end) termini face the cytosol and a single loop (aa 494-575) faces the intermembrane space.
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Affiliation(s)
- M R Gonzalez-Baro
- Department of Nutrition, School of Public Health and School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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115
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Abstract
Fatty acid biosynthesis, the first stage in membrane lipid biogenesis, is catalyzed in most bacteria by a series of small, soluble proteins that are each encoded by a discrete gene (Fig. 1; Table 1). This arrangement is termed the type II fatty acid synthase (FAS) system and contrasts sharply with the type I FAS of eukaryotes which is a dimer of a single large, multifunctional polypeptide. Thus, the bacterial pathway offers several unique sites for selective inhibition by chemotherapeutic agents. The site of action of isoniazid, used in the treatment of tuberculosis for 50 years, and the consumer antimicrobial agent triclosan were revealed recently to be the enoyl-ACP reductase of the type II FAS. The fungal metabolites, cerulenin and thiolactomycin, target the condensing enzymes of the bacterial pathway while the dehydratase/isomerase is inhibited by a synthetic acetylenic substrate analogue. Transfer of fatty acids to the membrane has also been inhibited via interference with the first acyltransferase step, while a new class of drugs targets lipid A synthesis. This review will summarize the data generated on these inhibitors to date, and examine where additional efforts will be required to develop new chemotherapeutics to help combat microbial infections.
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Affiliation(s)
- R J Heath
- Protein Science Division, Department of Infectious Diseases, St. Jude Children's Research Hospital, Tennessee 38105, Memphis, USA.
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116
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Turnbull AP, Rafferty JB, Sedelnikova SE, Slabas AR, Schierer TP, Kroon JT, Simon JW, Fawcett T, Nishida I, Murata N, Rice DW. Analysis of the structure, substrate specificity, and mechanism of squash glycerol-3-phosphate (1)-acyltransferase. Structure 2001; 9:347-53. [PMID: 11377195 DOI: 10.1016/s0969-2126(01)00595-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Glycerol-3-phosphate (1)-acyltransferase(G3PAT) catalyzes the incorporation of an acyl group from either acyl-acyl carrier proteins (acylACPs) or acyl-CoAs into the sn-1 position of glycerol 3-phosphate to yield 1-acylglycerol-3-phosphate. G3PATs can either be selective, preferentially using the unsaturated fatty acid, oleate (C18:1), as the acyl donor, or nonselective, using either oleate or the saturated fatty acid, palmitate (C16:0), at comparable rates. The differential substrate specificity for saturated versus unsaturated fatty acids seen within this enzyme family has been implicated in the sensitivity of plants to chilling temperatures. RESULTS The three-dimensional structure of recombinant G3PAT from squash chloroplast has been determined to 1.9 A resolution by X-ray crystallography using the technique of multiple isomorphous replacement and provides the first representative structure of an enzyme of this class. CONCLUSIONS The tertiary structure of G3PAT comprises two domains, the larger of which, domain II, features an extensive cleft lined by hydrophobic residues and contains at one end a cluster of positively charged residues flanked by a H(X)(4)D motif, which is conserved amongst many glycerolipid acyltransferases. We predict that these hydrophobic and positively charged residues represent the binding sites for the fatty acyl substrate and the phosphate moiety of the glycerol 3-phosphate, respectively, and that the H(X)(4)D motif is a critical component of the enzyme's catalytic machinery.
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Affiliation(s)
- A P Turnbull
- The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, S10 2TN, Sheffield, United Kingdom
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117
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Reina JJ, Heredia A. Plant cutin biosynthesis: the involvement of a new acyltransferase. TRENDS IN PLANT SCIENCE 2001; 6:296. [PMID: 11474501 DOI: 10.1016/s1360-1385(01)02012-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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118
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Coleman RA, Lewin TM, Muoio DM. Physiological and nutritional regulation of enzymes of triacylglycerol synthesis. Annu Rev Nutr 2001; 20:77-103. [PMID: 10940327 DOI: 10.1146/annurev.nutr.20.1.77] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although triacylglycerol stores play the critical role in an organism's ability to withstand fuel deprivation and are strongly associated with such disorders as diabetes, obesity, and atherosclerotic heart disease, information concerning the enzymes of triacylglycerol synthesis, their regulation by hormones, nutrients, and physiological conditions, their mechanisms of action, and the roles of specific isoforms has been limited by a lack of cloned cDNAs and purified proteins. Fortunately, molecular tools for several key enzymes in the synthetic pathway are becoming available. This review summarizes recent studies of these enzymes, their regulation under varying physiological conditions, their purported roles in synthesis of triacylglycerol and related glycerolipids, the possible functions of different isoenzymes, and the evidence for specialized cellular pools of triacylglycerol and glycerolipid intermediates.
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Affiliation(s)
- R A Coleman
- Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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119
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Evolution of Acyltransferase Genes: Origin and Diversification of the BAHD Superfamily of Acyltransferases Involved in Secondary Metabolism. EVOLUTION OF METABOLIC PATHWAYS 2000. [DOI: 10.1016/s0079-9920(00)80010-6] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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120
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Dircks LK, Ke J, Sul HS. A conserved seven amino acid stretch important for murine mitochondrial glycerol-3-phosphate acyltransferase activity. Significance of arginine 318 in catalysis. J Biol Chem 1999; 274:34728-34. [PMID: 10574940 DOI: 10.1074/jbc.274.49.34728] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the initial and committed step in glycerolipid biosynthesis. We previously cloned the cDNA sequence to murine mitochondrial GPAT (Yet, S-F., Lee, S., Hahm, Y. T., and Sul, H.S. (1993) Biochemistry 32, 9486-9491). We expressed the protein in insect cells which was targeted to mitochondria, purified, and reconstituted mitochondrial GPAT activity using phospholipids (Yet, S.-F., Moon, Y., and Sul, H. S. (1995) Biochemistry 34, 7303-7310). Deletion of the seven amino acids from mitochondrial GPAT, (312)IFLEGTR(318), which is highly conserved among acyltransferases in glycerolipid biosynthesis, drastically reduced mitochondrial GPAT activity. Treatment of mitochondrial GPAT with arginine-modifying agents, phenylglyoxal and cyclohexanedione, inactivated the enzyme. Two highly conserved arginine residues, Arg-318, in the seven amino stretch, and Arg-278, were identified. Substitution of Arg-318 with either alanine, histidine, or lysine reduced the mitochondrial GPAT activity by over 90%. On the other hand, although substitution of Arg-278 with alanine and histidine decreased mitochondrial GPAT activity by 90%, replacement with lysine reduced activity by only 25%. A substitution of the nonconserved Arg-279 with either alanine, histidine, or lysine did not alter mitochondrial GPAT activity. Moreover, R278K mitochondrial GPAT still showed sensitivity to arginine-modifying agents, as in the case of wild-type mitochondrial GPAT. These results suggest that Arg-318 may be critical for mitochondrial GPAT activity, whereas Arg-278 can be replaced by a basic amino acid. Examination of the other conserved residues in the seven amino acid stretch revealed that Phe-313 and Glu-315 are also important, but conservative substitutions can partially maintain activity; substitution with alanine reduced activity by 83 and 72%, respectively, whereas substituting Phe-313 with tyrosine and Glu-315 with glutamine had even lesser effect. In addition, there was no change in fatty acyl-CoA selectivity. Kinetic analysis of the R318K and R318A mitochondrial GPAT showed an 89 and 95%, respectively, decrease in catalytic efficiency but no major change in substrate binding as indicated by the K(m) values for palmitoyl-CoA and glycerol 3-phosphate. These studies indicate importance of the conserved seven amino acid stretch for mitochondrial GPAT activity and the significance of Arg-318 for catalysis.
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Affiliation(s)
- L K Dircks
- Department of Nutritional Sciences, University of California, Berkeley, California 94720, USA
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121
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Athenstaedt K, Daum G. Phosphatidic acid, a key intermediate in lipid metabolism. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 266:1-16. [PMID: 10542045 DOI: 10.1046/j.1432-1327.1999.00822.x] [Citation(s) in RCA: 242] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Phosphatidic acid (PtdOH) is a key intermediate in glycerolipid biosynthesis. Two different pathways are known for de novo formation of this compound, namely (a) the Gro3P (glycerol 3-phosphate) pathway, and (b) the GrnP (dihydroxyacetone phosphate) pathway. Whereas the former route of PtdOH synthesis is present in bacteria and all types of eukaryotes, the GrnP pathway is restricted to yeast and mammalian cells. In this review article, we describe the enzymes catalyzing de novo formation of PtdOH, their properties and their occurrence in different cell types and organelles. Much attention has recently been paid to the subcellular localization of enzymes involved in the biosynthesis of PtdOH. In all eukaryotic cells, microsomes (ER) harbour the complete set of enzymes catalyzing these pathways and are thus the usual organelle for PtdOH formation. In contrast, the contribution of mitochondria to PtdOH synthesis is restricted to certain enzymes and depends on the cell type. In addition, chloroplasts of plants, lipid particles of the yeast, and peroxisomes of mammalian cells are significantly involved in PtdOH biosynthesis. Redundant systems of acyltransferases, the interplay of organelles, regulation of the pathway on the compartmental level, and finally the contribution of alternative pathways (phosphorylation of diacylglycerol and cleavage of phospholipids by phospholipases) to PtdOH biosynthesis appear to be required for the balanced formation of this important lipid intermediate. Dysfunction of enzymes involved in PtdOH synthesis can result in severe defects of various cellular processes. In this context, the possible physiological role(s) of PtdOH and its related metabolites, lysophosphatidic acid and diacylglycerol, will be discussed.
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Affiliation(s)
- K Athenstaedt
- Institut für Biochemie, Technische Universität, Graz, Austria
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122
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Affiliation(s)
- L Dircks
- Department of Nutritional Sciences, University of California, Berkeley 94720, USA
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123
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Shih GC, Kahler CM, Swartley JS, Rahman MM, Coleman J, Carlson RW, Stephens DS. Multiple lysophosphatidic acid acyltransferases in Neisseria meningitidis. Mol Microbiol 1999; 32:942-52. [PMID: 10361297 DOI: 10.1046/j.1365-2958.1999.01404.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Lysophosphatidic acid (LPA) and phosphatidic acid (PA) are critical phospholipid intermediates in the biosynthesis of cell membranes. In Escherichia coli, LPA acyltransferase (1-acyl-sn-glycerol-3-phosphate acyltransferase; EC 2.3.1.51) catalyses the transfer of an acyl chain from either acyl-coenzyme A or acyl-acyl carrier protein onto LPA to produce PA. While E. coli possesses one essential LPA acyltransferase (PlsC), Neisseria meningitidis possesses at least two LPA acyltransferases. This study describes the identification and characterization of nlaB (neisserial LPA acyltransferase B), the second LPA acyltransferase identified in N. meningitidis. The gene was located downstream of the Tn916 insertion in N. meningitidis mutant 469 and differed in nucleotide and predicted amino acid sequence from the previously characterized neisserial LPA acyltransferase homologue nlaA. NlaB has specific LPA acyltransferase activity, as demonstrated by complementation of an E. coli plsC(Ts) mutant in trans, by decreased levels of LPA acyltransferase activity in nlaB mutants and by lack of complementation of E. coli plsB26,X50, a mutant defective in the first acyltransferase step in phospholipid biosynthesis. Meningococcal nlaA mutants accumulated LPA and demonstrated alterations in membrane phospholipid composition, yet retained LPA acyltransferase activity. In contrast, meningococcal nlaB mutants exhibited decreased LPA acyltransferase activity, but did not accumulate LPA or display any other observable membrane changes. We propose that N. meningitidis possesses at least two LPA acyltransferases to provide for the production of a greater diversity of membrane phospholipids.
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Affiliation(s)
- G C Shih
- Departments of Medicine and Microbiology and Immunology, Emory University School of Medicine, Department of Veterans Affairs Medical Center, Atlanta, GA 30303, USA
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124
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Lewin TM, Wang P, Coleman RA. Analysis of amino acid motifs diagnostic for the sn-glycerol-3-phosphate acyltransferase reaction. Biochemistry 1999; 38:5764-71. [PMID: 10231527 DOI: 10.1021/bi982805d] [Citation(s) in RCA: 215] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alignment of amino acid sequences from various acyltransferases [sn-glycerol-3-phosphate acyltransferase (GPAT), lysophosphatidic acid acyltransferase (LPAAT), acyl-CoA:dihydroxyacetone-phosphate acyltransferase (DHAPAT), 2-acylglycerophosphatidylethanolamine acyltransferase (LPEAT)] reveals four regions of strong homology, which we have labeled blocks I-IV. The consensus sequence for each conserved region is as follows: block I, [NX]-H-[RQ]-S-X-[LYIM]-D; block II, G-X-[IF]-F-I-[RD]-R; block III, F-[PLI]-E-G-[TG]-R-[SX]-[RX]; and block IV, [VI]-[PX]-[IVL]-[IV]-P-[VI]. We hypothesize that blocks I-IV and, in particular, the invariant amino acids contained within these regions form a catalytically important site in this family of acyltransferases. Using Escherichia coli GPAT (PlsB) as a model acyltransferase, we examined the role of the highly conserved amino acid residues in blocks I-IV in GPAT activity through chemical modification and site-directed mutagenesis experiments. We found that the histidine and aspartate in block I, the glycine in block III, and the proline in block IV all play a role in E. coli GPAT catalysis. The phenylalanine and arginine in block II and the glutamate and serine in block III appear to be important in binding the glycerol 3-phosphate substrate. Since blocks I-IV are also found in LPAAT, DHAPAT, and LPEAT, we believe that these conserved amino acid motifs are diagnostic for the acyltransferase reaction involving glycerol 3-phosphate, 1-acylglycerol 3-phosphate, and dihydroxyacetone phosphate substrates.
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Affiliation(s)
- T M Lewin
- Department of Nutrition, University of North Carolina, Chapel Hill 27599-7400, USA
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125
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Heath RJ, Rock CO. A missense mutation accounts for the defect in the glycerol-3-phosphate acyltransferase expressed in the plsB26 mutant. J Bacteriol 1999; 181:1944-6. [PMID: 10074094 PMCID: PMC93600 DOI: 10.1128/jb.181.6.1944-1946.1999] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The sn-glycerol-3-phosphate acyltransferase (plsB) catalyzes the first step in membrane phospholipid formation. A conditional Escherichia coli mutant (plsB26) has a single missense mutation (G1045A) predicting the expression of an acyltransferase with an Ala349Thr substitution. The PlsB26 protein had a significantly reduced glycerol-3-phosphate acyltransferase specific activity coupled with an elevated Km for glycerol-3-phosphate.
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Affiliation(s)
- R J Heath
- Department of Biochemistry, St Jude Children's Research Hospital, Memphis, Tennessee 38101, USA
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126
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Rehm BH, Krüger N, Steinbüchel A. A new metabolic link between fatty acid de novo synthesis and polyhydroxyalkanoic acid synthesis. The PHAG gene from Pseudomonas putida KT2440 encodes a 3-hydroxyacyl-acyl carrier protein-coenzyme a transferase. J Biol Chem 1998; 273:24044-51. [PMID: 9727022 DOI: 10.1074/jbc.273.37.24044] [Citation(s) in RCA: 219] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To investigate the metabolic link between fatty acid de novo synthesis and polyhydroxyalkanoic acid (PHA) synthesis, we isolated mutants of Pseudomonas putida KT2440 deficient in this metabolic route. The gene phaG was cloned by phenotypic complementation of these mutants; it encoded a protein of 295 amino acids with a molecular mass of 33,876 Da, and the amino acid sequence exhibited 44% amino acid identity to the primary structure of the rhlA gene product, which is involved in the rhamnolipid biosynthesis in Pseudomonas aeruginosa PG201. S1 nuclease protection assay identified the transcriptional start site 239 base pairs upstream of the putative translational start codon. Transcriptional induction of phaG was observed when gluconate was provided, and PHA synthesis occurred from this carbon source. No complementation of the rhlA mutant P. aeruginosa UO299-harboring plasmid pBHR81, expressing phaG gene under lac promoter control, was obtained. Heterologous expression of phaG in Pseudomonas oleovorans, which is not capable of PHA synthesis from gluconate, enabled PHA synthesis on gluconate as the carbon source. Native recombinant PhaG was purified by native polyacrylamide gel electrophoresis from P. oleovorans-harboring plasmid pBHR81. It catalyzes the transfer of the acyl moiety from in vitro synthesized 3-hydroxydecanoyl-CoA to acyl carrier protein, indicating that PhaG exhibits a 3-hydroxyacyl-CoA-acyl carrier protein transferase activity.
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Affiliation(s)
- B H Rehm
- Institut für Mikrobiologie, Westfälische Wilhelms-Universität Münster, Corrensstrabetae 3, D-48149, Münster, Germany
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