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Lin D, Yan K, Chen L, Chen J, Xu J, Xie Z, Li Z, Lin S, Li J, Chen Z. Hypoxia-induced reprogramming of glucose-dependent metabolic pathways maintains the stemness of human bone marrow-derived endothelial progenitor cells. Sci Rep 2023; 13:8776. [PMID: 37258701 DOI: 10.1038/s41598-023-36007-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 05/27/2023] [Indexed: 06/02/2023] Open
Abstract
The benefits of hypoxia for maintaining the stemness of cultured human bone marrow-derived endothelial progenitor cells (BM EPCs) have previously been demonstrated but the mechanisms responsible remain unclear. Growing evidences suggest that cellular metabolism plays an important role in regulating stem cell fate and self-renewal. Here we aimed to detect the changes of glucose metabolism and to explore its role on maintaining the stemness of BM EPCs under hypoxia. We identified the metabolic status of BM EPCs by using extracellular flux analysis, LC-MS/MS, and 13C tracing HPLC-QE-MS, and found that hypoxia induced glucose metabolic reprogramming, which manifested as increased glycolysis and pentose phosphate pathway (PPP), decreased tricarboxylic acid (TCA) and mitochondrial respiration. We further pharmacologically altered the metabolic status of cells by employing various of inhibitors of key enzymes of glycolysis, PPP, TCA cycle and mitochondria electron transport chain (ETC). We found that inhibiting glycolysis or PPP impaired cell proliferation either under normoxia or hypoxia. On the contrary, inhibiting pyruvate oxidation, TCA or ETC promoted cell proliferation under normoxia mimicking hypoxic conditions. Moreover, promoting pyruvate oxidation reverses the maintenance effect of hypoxia on cell stemness. Taken together, our data suggest that hypoxia induced glucose metabolic reprogramming maintains the stemness of BM EPCs, and artificial manipulation of cell metabolism can be an effective way for regulating the stemness of BM EPCs, thereby improving the efficiency of cell expansion in vitro.
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Affiliation(s)
- Dongni Lin
- The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory On Brain Function Repair and Regeneration, Department of Neurosurgery, The National Key Clinical Specialty, Zhujiang Hospital, Southern Medical University, 253# Gongye RD, Guangzhou, 510282, China
| | - Kaihao Yan
- The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory On Brain Function Repair and Regeneration, Department of Neurosurgery, The National Key Clinical Specialty, Zhujiang Hospital, Southern Medical University, 253# Gongye RD, Guangzhou, 510282, China
| | - Lingyun Chen
- Hygiene Detection Center, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China
| | - Junxiong Chen
- The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory On Brain Function Repair and Regeneration, Department of Neurosurgery, The National Key Clinical Specialty, Zhujiang Hospital, Southern Medical University, 253# Gongye RD, Guangzhou, 510282, China
| | - Jianing Xu
- The Second School of Clinical Medicine, Undergraduate Innovation and Entrepreneurship Project, Southern Medical University, 253 Gongye Road, Guangzhou, 510282, China
| | - Zijing Xie
- The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory On Brain Function Repair and Regeneration, Department of Neurosurgery, The National Key Clinical Specialty, Zhujiang Hospital, Southern Medical University, 253# Gongye RD, Guangzhou, 510282, China
| | - Zhujun Li
- The Second School of Clinical Medicine, Undergraduate Innovation and Entrepreneurship Project, Southern Medical University, 253 Gongye Road, Guangzhou, 510282, China
| | - Shuo Lin
- The Second School of Clinical Medicine, Undergraduate Innovation and Entrepreneurship Project, Southern Medical University, 253 Gongye Road, Guangzhou, 510282, China
| | - Jinghuan Li
- The Second School of Clinical Medicine, Undergraduate Innovation and Entrepreneurship Project, Southern Medical University, 253 Gongye Road, Guangzhou, 510282, China
| | - Zhenzhou Chen
- The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory On Brain Function Repair and Regeneration, Department of Neurosurgery, The National Key Clinical Specialty, Zhujiang Hospital, Southern Medical University, 253# Gongye RD, Guangzhou, 510282, China.
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Cloning, expression, characterization, and immunological properties of citrate synthase from Echinococcus granulosus. Parasitol Res 2019; 118:1811-1820. [PMID: 31049696 DOI: 10.1007/s00436-019-06334-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 04/18/2019] [Indexed: 12/15/2022]
Abstract
The larval stages of the tapeworm Echinococcus granulosus (Cestoda: Taeniidae) are the causative agent of cystic echinococcosis, one of the most important parasitic zoonoses worldwide. E. granulosus has a complete pathway for the tricarboxylic acid cycle (TCA), in which citrate synthase (CS) is the key enzyme. Here, we cloned and expressed CS from E. granulosus (Eg-CS) and report its molecular characterization. The localization of this protein during different developmental stages and mRNA expression patterns during H2O2 treatment were determined. We found that Eg-CS is a highly conserved protein, consisting of 466 amino acids. In western blotting assays, recombinant Eg-CS (rEg-CS) reacted with E. granulosus-positive sheep sera and anti-rEg-CS rabbit sera, indicating that Eg-CS has good antigenicity and immunoreactivity. Localization studies, performed using immunohistochemistry, showed that Eg-CS is ubiquitously expressed in the larva, germinal layer, and adult worm sections of E. granulosus. Eg-CS mRNA expression levels increased following H2O2 exposure. In conclusion, citrate synthase might be involved in the metabolic process in E. granulosus. An assessment of the serodiagnostic potential of rEg-CS based on indirect ELISA showed that, although sensitivity (93.55%) and specificity (80.49%) are high, cross-reactivity with other parasites precludes its use as a diagnostic antigen.
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Chen LY, Yang B, Zhou L, Ren F, Duan ZP, Ma YJ. Promotion of mitochondrial energy metabolism during hepatocyte apoptosis in a rat model of acute liver failure. Mol Med Rep 2015; 12:5035-41. [PMID: 26135512 PMCID: PMC4581801 DOI: 10.3892/mmr.2015.4029] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 05/08/2015] [Indexed: 12/27/2022] Open
Abstract
Hepatocyte apoptosis and energy metabolism in mitochondria have an important role in the mechanism of acute liver failure (ALF). However, data on the association between apoptosis and the energy metabolism of hepatocytes are lacking. The current study assessed the activity of several key enzymes in mitochondria during ALF, including citrate synthase (CS), carnitine palmitoyltransferase-1 (CPT-1) and cytochrome c oxidase (COX), which are involved in hepatocyte energy metabolism. A total of 40 male Sprague-Dawley rats were divided into five groups and administered D-galactosamine and lipopolysaccharide to induce ALF. Hepatic pathology and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling examinations indicated that hepatocyte apoptosis was observed at 4 h and increased 8 h after ALF. Hepatocyte necrosis appeared at 12 h and was significantly higher at 24 h with inflammatory cell invasion. The results measured by electron microscopy indicated that ultrastructural changes in mitochondria began at 4 h and the mitochondrial outer membrane was completely disrupted at 24 h resulting in mitochondrial collapse. The expression of CS, CPT-1 and COX was measured and analyzed using assay kits. The activity and protein expression of CS, CPT-1 and COX began to increase at 4 h, reached a peak at 8 h and decreased at 12 h during ALF. The activities of CS, CPT-1 and COX were enhanced during hepatocyte apoptosis suggesting that these enzymes are involved in the initiation and development of ALF. Therefore, these results demonstrated that energy metabolism is important in hepatocyte apoptosis during ALF and hepatocyte apoptosis is an active and energy-consuming procedure. The current study on how hepatocyte energy metabolism affects the transmission of death signals may provide a basis for the early diagnosis and development of an improved therapeutic strategy for ALF.
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Affiliation(s)
- Li-Yan Chen
- The Second Department of Infectious Diseases, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Baoshan Yang
- The Second Department of Infectious Diseases, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Li Zhou
- Beijing Artificial Liver Treatment and Training Center, Beijing Youan Hospital, Capital Medical University, Beijing 100069, P.R. China
| | - Feng Ren
- Beijing Artificial Liver Treatment and Training Center, Beijing Youan Hospital, Capital Medical University, Beijing 100069, P.R. China
| | - Zhong-Ping Duan
- Beijing Artificial Liver Treatment and Training Center, Beijing Youan Hospital, Capital Medical University, Beijing 100069, P.R. China
| | - Ying-Ji Ma
- The Fourth Department of Infectious Diseases, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
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4
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Lanouette S, Mongeon V, Figeys D, Couture JF. The functional diversity of protein lysine methylation. Mol Syst Biol 2014; 10:724. [PMID: 24714364 PMCID: PMC4023394 DOI: 10.1002/msb.134974] [Citation(s) in RCA: 188] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Large‐scale characterization of post‐translational modifications (PTMs), such as phosphorylation, acetylation and ubiquitination, has highlighted their importance in the regulation of a myriad of signaling events. While high‐throughput technologies have tremendously helped cataloguing the proteins modified by these PTMs, the identification of lysine‐methylated proteins, a PTM involving the transfer of one, two or three methyl groups to the ε‐amine of a lysine side chain, has lagged behind. While the initial findings were focused on the methylation of histone proteins, several studies have recently identified novel non‐histone lysine‐methylated proteins. This review provides a compilation of all lysine methylation sites reported to date. We also present key examples showing the impact of lysine methylation and discuss the circuitries wired by this important PTM.
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Affiliation(s)
- Sylvain Lanouette
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
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5
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Haaksma E, Timmerman H, Weinstein H. The Effect of a Protein Environment on the Proposed Activation Mechanism of the Histamine H2-Receptor. Isr J Chem 2013. [DOI: 10.1002/ijch.199100047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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6
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Nutritional intervention during gestation alters growth, body composition and gene expression patterns in skeletal muscle of pig offspring. Animal 2011; 5:1195-206. [DOI: 10.1017/s1751731111000176] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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7
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Orczewska JI, Hartleben G, O'Brien KM. The molecular basis of aerobic metabolic remodeling differs between oxidative muscle and liver of threespine sticklebacks in response to cold acclimation. Am J Physiol Regul Integr Comp Physiol 2010; 299:R352-64. [PMID: 20427717 DOI: 10.1152/ajpregu.00189.2010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We sought to determine the molecular basis of elevations in aerobic metabolic capacity in the oxidative muscle and liver of Gasterosteus aculeatus in response to cold acclimation. Fishes were cold- or warm-acclimated for 9 wk and harvested on days 1, 2, and 3 and weeks 1, 4, and 9 of cold acclimation at 8 degrees C, and on day 1 and week 9 of warm acclimation at 20 degrees C. Mitochondrial volume density was quantified using transmission electron microscopy and stereological techniques in warm- and cold-acclimated fishes harvested after 9 wk at 20 or 8 degrees C. Changes in aerobic metabolic capacity were assessed by measuring the maximal activity of citrate synthase (CS) and cytochrome-c oxidase (COX) in fishes harvested throughout the acclimation period. Transcript levels of the aerobic metabolic genes CS, COXIII, and COXIV, and known regulators of mitochondrial biogenesis, including peroxisome proliferator-activated receptor-gamma coactivators-1alpha and -1beta (PGC-1alpha and PGC-1beta), nuclear respiratory factor-1 (NRF-1), and mitochondrial transcription factor-A were measured in fishes harvested throughout the acclimation period using quantitative real-time PCR. The maximal activities of CS and COX increased in response to cold acclimation in both tissues, but mitochondrial volume density only increased in oxidative muscle (P < 0.05). The time course for changes in aerobic metabolic capacity differed between liver and muscle. The expression of CS increased within 1 wk of cold acclimation in liver and was correlated with an increase in mRNA levels of NRF-1 and PGC-1beta. Transcript levels of aerobic metabolic genes increased later in oxidative muscle, between weeks 4 and 9 of cold acclimation and were correlated with an increase in mRNA levels of NRF-1 and PGC-1alpha. These results show that aerobic metabolic remodeling differs between liver and muscle in response to cold acclimation and may be triggered by different stimuli.
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Affiliation(s)
- J I Orczewska
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska 99775, USA
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8
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Oves-Costales D, Song L, Challis GL. Enantioselective desymmetrisation of citric acid catalysed by the substrate-tolerant petrobactin biosynthetic enzyme AsbA. Chem Commun (Camb) 2009:1389-91. [DOI: 10.1039/b823147h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Winger AM, Taylor NL, Heazlewood JL, Day DA, Millar AH. Identification of intra- and intermolecular disulphide bonding in the plant mitochondrial proteome by diagonal gel electrophoresis. Proteomics 2008; 7:4158-70. [PMID: 17994621 DOI: 10.1002/pmic.200700209] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Redox active proteins in plant mitochondria were examined using 2-D oxidant/reductant diagonal-SDS-PAGE to separate and identify proteins with intermolecular or intramolecular disulphide bonds using diamide in the first dimension and DTT in the second dimension. Eighteen proteins spots were resolved either above or below the diagonal and these were in-gel digested and identified by MS/MS. This analysis revealed intermolecular disulphide bonds in alternative oxidase, O-acetylserine (thiol) lyase, citrate synthase and between subunits of the ATP synthase. Intramolecular disulphide bonds were observed in a range of mitochondrial dehydrogenases, elongation factor Tu, adenylate kinase and the phosphate translocator. Many of the soluble proteins found were known glutaredoxin/thioredoxin targets in other plants, but the membrane proteins were not found by these methods nor were the nature of the disulphides able to be investigated. The accessibility of thiols involved in disulphide bonds to modification by a lipid derived aldehyde gave an insight into the potential impact of Cys modification on redox-functions in mitochondria during lipid peroxidation. Comparison of the protein sequences of the identified proteins with homologs from other species has identified specific Cys residues that may be responsible for plant-specific redox modulations of mitochondrial proteins.
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Affiliation(s)
- Alison M Winger
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, WA, Australia
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10
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Smith LD, Stevenson KJ, Hough DW, Danson MJ. Citrate synthase from the thermophilic archaebacteriaThermoplasma acidophilumandSulfolobus acidocaldarius. FEBS Lett 2001. [DOI: 10.1016/0014-5793(87)81174-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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11
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Howard BR, Endrizzi JA, Remington SJ. Crystal structure of Escherichia coli malate synthase G complexed with magnesium and glyoxylate at 2.0 A resolution: mechanistic implications. Biochemistry 2000; 39:3156-68. [PMID: 10715138 DOI: 10.1021/bi992519h] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The crystal structure of selenomethionine-substituted malate synthase G, an 81 kDa monomeric enzyme from Escherichia coli has been determined by MAD phasing, model building, and crystallographic refinement to a resolution of 2.0 A. The crystallographic R factor is 0.177 for 49 242 reflections observed at the incident wavelength of 1.008 A, and the model stereochemistry is satisfactory. The basic fold of the enzyme is that of a beta8/alpha8 (TIM) barrel. The barrel is centrally located, with an N-terminal alpha-helical domain flanking one side. An inserted beta-sheet domain folds against the opposite side of the barrel, and an alpha-helical C-terminal domain forms a plug which caps the active site. Malate synthase catalyzes the condensation of glyoxylate and acetyl-coenzyme A and hydrolysis of the intermediate to yield malate and coenzyme A, requiring Mg(2+). The structure reveals an enzyme-substrate complex with glyoxylate and Mg(2+) which coordinates the aldehyde and carboxylate functions of the substrate. Two strictly conserved residues, Asp631 and Arg338, are proposed to provide concerted acid-base chemistry for the generation of the enol(ate) intermediate of acetyl-coenzyme A, while main-chain hydrogen bonds and bound Mg(2+) polarize glyoxylate in preparation for nucleophilic attack. The catalytic strategy of malate synthase appears to be essentially the same as that of citrate synthase, with the electrophile activated for nucleophilic attack by nearby positive charges and hydrogen bonds, while concerted acid-base catalysis accomplishes the abstraction of a proton from the methyl group of acetyl-coenzyme A. An active site aspartate is, however, the only common feature of these two enzymes, and the active sites of these enzymes are produced by quite different protein folds. Interesting similarities in the overall folds and modes of substrate recognition are discussed in comparisons of malate synthase with pyruvate kinase and pyruvate phosphate dikinase.
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Affiliation(s)
- B R Howard
- Institute of Molecular Biology and Departments of Chemistry and Physics, University of Oregon, Eugene, Oregon 97403, USA
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Winger QA, Hill JR, Watson AJ, Westhusin ME. Characterization of a bovine cDNA encoding citrate synthase, and presence of citrate synthase mRNA during bovine pre-attachment development. Mol Reprod Dev 2000; 55:14-9. [PMID: 10602269 DOI: 10.1002/(sici)1098-2795(200001)55:1<14::aid-mrd3>3.0.co;2-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Citrate synthase is a key regulatory metabolic enzyme that catalyzes the first step in the tricarboxylic acid (TCA) cycle, the synthesis of citrate from acetyl coenzyme A and oxaloacetate. Aerobic metabolism via the TCA cycle is high in bovine embryos at the 4-cell stage then decreases until the compact morula stage before increasing at the expanded blastocyst stage. This study characterizes the presence of citrate synthase mRNA in bovine pre-attachment embryos to determine if a variation in mRNA transcript expression patterns is associated with previous reports of the patterns of TCA cycle activity. The reverse transcription-polymerase chain reaction (RT-PCR) method was used to detect citrate synthase mRNA from the 1-cell to blastocyst stage of bovine embryo development, and in embryos cultured under either an atmosphere of 5% CO(2) in air or 5% CO(2)/5% O(2)/90%N(2). The nucleotide sequence encoding citrate synthase was determined from bovine heart cDNA by the rapid amplification of cDNA ends (RACE) technique. This 1455-bp nucleotide fragment contained an open reading frame that encoded a deduced protein of 466 amino acids. The bovine nucleotide sequence was 92.1% and 93.8% identical to the human and porcine coding sequence, respectively. The amino acid sequence predicted from the bovine sequence is 95.1% identical to the human sequence and 96.3% identical to the porcine sequence. The porcine sequence contains a stop codon that results in a peptide truncated by 2 amino acids. The detection of citrate synthase transcripts from the 1-cell to blastocyst stage demonstrates that the decrease in TCA cycle activity observed following the 4-cell stage is not associated with an absence of citrate synthase mRNA.
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Affiliation(s)
- Q A Winger
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843-4466, USA
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Lundquist JT, Dix TA. Synthesis and human neurotensin receptor binding activities of neurotensin(8-13) analogues containing position 8 alpha-azido-N-alkylated derivatives of ornithine, lysine, and homolysine. J Med Chem 1999; 42:4914-8. [PMID: 10579853 DOI: 10.1021/jm9903444] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of neurotensin(8-13) (NT) analogues were synthesized through intermediates in which the N-terminal Arg(8) was replaced by various omega-bromo-2(S)-azido residues spanning 3-5 methylene units in side-chain length. Subsequent nucleophilic substitution of the omega-bromo groups with ammonia, methylamine, dimethylamine, or trimethylamine provided peptides containing N-terminal 2(S)-azido residues containing primary through quaternary N-alkylated side chains corresponding in length to ornithine, Lys, and homolysine. The synthetic procedure appears applicable for incorporation of a wide variety of amine-containing nonnatural amino acids into peptides. The particular modifications were intended to enhance physiochemical properties of NT(8-13) responsible for human NT 1 receptor (hNTR) binding, overall lipophilicity, and stability that may influence the potency of the peptides in vivo. When the peptides were tested for hNTR binding, the affinities in each series followed the order primary > secondary > tertiary > quaternary amine with the homolysine side-chain length being favored. All analogues possess binding affinities between acetyl-NT(8-13) and NT(8-13) indicating that the sterically less bulky alpha-azido may be inherently preferable to the acetyl group for N-terminal protection. This study extends the strategy of modifying amine-containing drugs through alkylations to peptide modification. The set of alkylated side chains also offers a new method of steric selection between receptor subtypes and could be used to modify the properties and biological effects of any peptide that contains cationic residues.
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Affiliation(s)
- J T Lundquist
- Department of Pharmaceutical Sciences, Medical University of South Carolina, Charleston 29425-2303, USA
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14
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Abstract
The high resolution refined structures of 23 enzymes were analyzed to determine the properties of amino acids involved in active site regions. These regions were found to be rich in G-X-Y or Y-X-G oligopeptides, where X and Y are polar and non-polar residues, respectively, that are small and with low polarity. Other regions of the enzyme molecules have significantly fewer of these sequences. These features suggest that glycine residues may provide flexibility necessary for enzyme active sites to change conformation, and the G-X-Y or Y-X-G oligopeptides may be a motif for the formation of enzyme active sites.
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Affiliation(s)
- B X Yan
- Institute of Microbiology, National Laboratory of Microbial Technology, Shandong University, Jinan 250100, China
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15
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Durchschlag H, Zipper P, Purr G, Jaenicke R. Comparative studies of structural properties and conformational changes of proteins by analytical ultracentrifugation and other techniques. Colloid Polym Sci 1996. [DOI: 10.1007/bf00663444] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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16
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Mitchell CG, Anderson SC, el-Mansi EM. Purification and characterization of citrate synthase isoenzymes from Pseudomonas aeruginosa. Biochem J 1995; 309 ( Pt 2):507-11. [PMID: 7626013 PMCID: PMC1135760 DOI: 10.1042/bj3090507] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Two types of citrate synthase (CS) have been purified from Pseudomonas aeruginosa, a 'large' form (CSI) and a 'small' form (CSII). The M(r)s of the CSI and CSII isoenzymes were determined to be 240,000 +/- 16,000 (mean +/- S.E.M.) and 80,300 +/- 3800 respectively. Chemical cross-linking of the native enzymes with either dimethyl suberimidate or glutaraldehyde followed by electrophoretic analysis by SDS/PAGE showed that CSI is a hexamer and CSII is a dimer. SDS/PAGE showed that CSI and CSII each consist of a single subunit type, of M(r) 42,000 +/- 2000 and M(r) 36,500 +/- 2000 respectively. CSI and CSII were also shown to be distinct kinetically, immunologically and in terms of their regulatory properties. It is suggested that the CS isoenzymes are products of different structural genes.
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Affiliation(s)
- C G Mitchell
- Department of Biological Sciences, Napier University, Edinburgh, U.K
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17
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Man WJ, Li Y, O'Connor CD, Wilton DC. The effect of replacing the conserved active-site residues His-264, Asp-312 and Arg-314 on the binding and catalytic properties of Escherichia coli citrate synthase. Biochem J 1994; 300 ( Pt 3):765-70. [PMID: 8010958 PMCID: PMC1138232 DOI: 10.1042/bj3000765] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The first step in the overall catalytic mechanism of citrate synthase is the binding and polarization of oxaloacetate. Active-site residues Arg-314, Asp-312 and His-264 in Escherichia coli citrate synthase, which are involved in oxaloacetate binding, were converted by site-directed mutagenesis to Gln-314, Asn-312 and Asn-264 respectively. The R314Q and D312N mutants expressed negligible overall catalytic activity at pH 8.0, the normal assay pH, but substantial activities for the partial reactions that reflect the cleavage and hydrolysis of the substrate intermediate citryl-CoA. However, when the pH was lowered to 7.0, the overall reaction of the mutants became significant, in contrast to the wild-type enzyme, whereas the two mutants exhibited reduced activities for the partial reactions. This result is consistent with the existence of a rate-limiting step between the two partial reactions for these mutants that is pH-dependent. The Km for oxaloacetate for the two mutants was increased 10-fold and was paralleled by an increase in the Km for citryl-CoA, whereas the Km for acetyl-CoA was increased only 2-fold. Overall, there was a striking parallel between the results obtained for these two mutants, which suggests that they are functionally linked in the E. coli enzyme. The equivalent of these two residues form a salt bridge in the pig heart citrate synthase crystal structure. The H264N mutant, in which the amide nitrogen of asparagine should mimic the delta-nitrogen of histidine, showed negligible activity in terms of both overall and partial catalysis, which may result from a hindrance of conformational change upon oxaloacetate binding. The affinity of this mutant for oxaloacetate appeared to be greatly reduced when investigated using indirect fluorescence and chemical modification techniques.
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Affiliation(s)
- W J Man
- Department of Biochemistry, University of Southampton, U.K
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18
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Patton AJ, Hough DW, Towner P, Danson MJ. Does Escherichia coli possess a second citrate synthase gene? EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 214:75-81. [PMID: 8508809 DOI: 10.1111/j.1432-1033.1993.tb17898.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Escherichia coli possesses a hexameric citrate synthase that exhibits allosteric kinetics and regulatory sensitivity, and for which the gene (gltA) has previously been cloned and sequenced. A citrate-synthase-deficient strain of E. coli (K114) has been mutated to generate a revertant (K114r4) that produces a dimeric citrate synthase with altered kinetic and regulatory properties. On cloning and sequencing the gltA gene from both K114 and K114r4, a single mutation was found that caused the replacement of Asp362 with Asn. Asp362 has been previously shown to be a catalytically essential residue in E. coli citrate synthase, and we demonstrate that the hexameric enzyme produced on expression of the gltA gene from K114 and K114r4 is inactive. The dimeric citrate synthase from K114r4 has been purified and shown to be immunologically distinct from the wild-type hexameric enzyme. Determination of its N-terminal amino acid sequence demonstrates that the mutant citrate synthase is encoded by a gene distinct from the E. coli gltA gene. The N-terminal sequence is compared with those of other eukaryotic, eubacterial and archaebacterial citrate synthases.
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Affiliation(s)
- A J Patton
- Department of Biochemistry, University of Bath, England
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19
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Ech-Cherif el-Kettani MA, Durup J. Theoretical determination of conformational paths in citrate synthase. Biopolymers 1992; 32:561-74. [PMID: 1515547 DOI: 10.1002/bip.360320512] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two methods are developed for the theoretical determination of a conformational path between two well-documented forms, a closed form and the open form [Remington et al. (1982) J. Mol. Biol. 158, 111-152] of pig heart citrate synthase, a dimeric enzyme of 2 x 437 residues. The first method uses the minimization of the sum of the potential energies at a set of equidistant points, according to Elber and Karplus [(1987) Chem. Phys. Lett. 139, 375-380]. The initialization of the algorithm is modified to account for large-angle rotations of many groups by performing the interpolations in the space of internal polar coordinates of a set of generalized Jacobi vectors earlier introduced by Durup [(1991) J. Phys. Chem. 95, 1817-1829] and by carefully testing all choices of directions of rotation for determining the initialized midpoint between the known forms. The path includes intermediate points, created by successive splittings of each interval into two equal parts, with a partial energy minimization performed after each splitting. The minimization encounters the well-known local-minima problem, which here is handled by low-temperature molecular dynamics annealing. It is shown that the best ratio of potential energy decrease to rms deviation is achieved by running the dynamics at 50 K, as compared to 100 K and above. The main character of the path obtained is the occurrence of strong to-and-fro variations of some dihedral angles at specific stages along the path. The second method, which we name directed dynamics, uses only low-temperature molecular dynamics simulations by starting trajectories from each of the two known forms with initial velocities directed toward the other one. The procedure is iterated by restarting trajectory pairs after the points of closest approach of the preceding pair. The two half-paths thus built eventually meet after 70 iterations. This method provides a second path with strong similarities, as well as some differences, with respect to the path obtained by the first method.
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20
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Glutamate-malate metabolism in liver mitochondria. A model constructed on the basis of mitochondrial levels of enzymes, specificity, dissociation constants, and stoichiometry of hetero-enzyme complexes. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50035-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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21
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Affiliation(s)
- S J Remington
- Department of Physics, University of Oregon, Eugene 97403
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22
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Man WJ, Li Y, O'Connor CD, Wilton DC. Conversion of citrate synthase into citryl-CoA lyase as a result of mutation of the active-site aspartic acid residue to glutamic acid. Biochem J 1991; 280 ( Pt 2):521-6. [PMID: 1684105 PMCID: PMC1130579 DOI: 10.1042/bj2800521] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The active-site aspartic acid residue, Asp-362, of Escherichia coli citrate synthase was changed by site-directed mutagenesis to Glu-362, Asn-362 or Gly-362. Only very low catalytic activity could be detected with the Asp----Asn and Asp----Gly mutations. The Asp----Glu mutation produced an enzyme that expressed about 0.8% of the overall catalytic rate, and the hydrolysis step in the reaction, monitored as citryl-CoA hydrolysis, was inhibited to a similar extent. However, the condensation reaction, measured in the reverse direction as citryl-CoA cleavage to oxaloacetate and acetyl-CoA, was not affected by the mutation, and this citryl-CoA lyase activity was the major catalytic activity of the mutant enzyme. This high condensation activity in an enzyme in which the subsequent hydrolysis step was about 98% inhibited permitted considerable exchange of the methyl protons of acetyl-CoA during catalysis by the mutant enzyme. The Km for oxaloacetate was not significantly altered in the D362E mutant enzyme, whereas the Km for acetyl-CoA was about 5 times lower. A mechanism is proposed in which Asp-362 is involved in the hydrolysis reaction of this enzyme, and not as a base in the deprotonation of acetyl-CoA as recently suggested by others. [Karpusas, Branchaud & Remington (1990) Biochemistry 29, 2213-2219; Alter, Casazza, Zhi, Nemeth, Srere & Evans, (1990) Biochemistry 29, 7557-7563].
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Affiliation(s)
- W J Man
- Department of Biochemistry, University of Southampton, Bassett Crescent East, U.K
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23
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David M, Lubinsky-Mink S, Ben-Zvi A, Suissa M, Ulitzur S, Kuhn J. Citrate synthase from Mycobacterium smegmatis. Cloning, sequence determination and expression in Escherichia coli. Biochem J 1991; 278 ( Pt 1):225-34. [PMID: 1883331 PMCID: PMC1151472 DOI: 10.1042/bj2780225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A Mycobacterium smegmatis PstI library was constructed by cloning these fragments downstream from the lac promoter of the expression vector pHG171. Three identically sized clones were isolated by complementation of an Escherichia coli strain (chi 2338) deficient in citrate synthase. One insert (pBL265) was used in hybridization experiments with DNA from E. coli and M. smegmatis and it was demonstrated that the clones were indeed from M. smegmatis. The transcription of the M. smegmatis citrate synthase gene in E. coli relied upon the lac promoter. In translation experiments performed in vitro pBL265 gave rise to a novel protein of about 42 kDa. This band was not seen in 'opposite-orientation' subclones. Various subclones in which the 5'-end was shortened nevertheless complement E. coli chi 2338 and produce the 42 kDa protein. This demonstrates that the M. smegmatis citrate synthase gene uses its own ribosome-binding site in E. coli. The relevant 1.8 kb of the 2.8 kb insert was sequenced. A consensus E. coli ribosome-binding site was found centred precisely 10 bp upstream of the methionine codon. Other interesting features revealed by the sequence are discussed. Citrate synthase activity was assayed in vitro and the mycobacterial enzyme was found to be similar to those of the Gram-positive bacteria.
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24
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Alter GM, Casazza JP, Zhi W, Nemeth P, Srere PA, Evans CT. Mutation of essential catalytic residues in pig citrate synthase. Biochemistry 1990; 29:7557-63. [PMID: 1702991 DOI: 10.1021/bi00485a003] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Two amino acid residues, His274 and Asp375, were replaced singly in the active site of pig citrate synthase (PCS) with Gly274, Arg274, Gly375, Asn375, Glu375, and Gln375. The nonmutant protein and the mutant proteins were expressed in and purified from Escherichia coli, and the effects of these amino acid substitutions on the overall reaction rate and conformation of the PCS protein were studied by initial velocity and full time course kinetic analysis, behavior during affinity column chromatography, and monoclonal antibody reactivity. Native and mutant proteins purified similarly had a subunit molecular weight of 50,000 and were homologous when examined with 10 independent a-PCS monoclonal IgGs or with a polyclonal anti-PHCS serum. No activity was detected for Asn375 or Gln375. The kcats of the other purified mutant proteins, however, were decreased by about 10(3) compared to the nonmutant enzyme activity. The Km for oxalacetate was decreased 10-fold in the Glu375 protein and was reduced by half in Gly274 and Arg274 PCSs, while the Km for acetyl-CoA was decreased 2-3-fold in Gly274, Arg274, and Gln375 PCSs. A mechanism is proposed that electrostatically links His274 and Asp375.
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Affiliation(s)
- G M Alter
- Pre-Clinical Science Unit, Department of Veterans Affairs Medical Center, Dallas, Texas 75216
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25
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Rogers SW, Rechsteiner M. Degradation of structurally characterized proteins injected into HeLa cells. Basic measurements. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)77711-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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26
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Jordan PM, Thomas SD, Warren MJ. Purification, crystallization and properties of porphobilinogen deaminase from a recombinant strain of Escherichia coli K12. Biochem J 1988; 254:427-35. [PMID: 3052434 PMCID: PMC1135095 DOI: 10.1042/bj2540427] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Porphobilinogen deaminase has been purified and crystallized from an overproducing recombinant strain of Escherichia coli harbouring a hemC-containing plasmid which has permitted the purification of milligram quantities of the enzyme. Determination of the Mr of the enzyme by SDS/polyacrylamide-gel electrophoresis (35,000) and gel filtration (32,000) agrees with the gene-derived Mr of 33,857. The enzyme has a Km of 19 +/- 7 microM, an isoelectric point of 4.5 and an N-terminal sequence NH2-MLDNVLRIAT. The substrate, porphobilinogen, binds to the active-site dipyrromethane cofactor to form three intermediate complexes: ES, ES2 and ES3. The gene-derived primary structure of the E. coli deaminase is compared with that derived from the cDNA of the human enzyme.
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Affiliation(s)
- P M Jordan
- Department of Biochemistry, University of Southampton, U.K
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27
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Else AJ, Danson MJ, Weitzman PD. Models of proteolysis of oligomeric enzymes and their applications to the trypsinolysis of citrate synthases. Biochem J 1988; 254:437-42. [PMID: 3140803 PMCID: PMC1135096 DOI: 10.1042/bj2540437] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A simple statistical approach was used to generate predictive models of the proteolysis of multisubunit enzymes in order to correlate the loss of enzyme activity with the loss of native subunit. The models were applied to the trypsinolysis of the citrate synthases of pig heart, Bacillus megaterium and Escherichia coli. With the dimeric citrate synthases (pig heart and B. megaterium) trypsinolysis of one of the subunits appears to destroy the activity of the whole enzymic molecule. The hexameric E. coli citrate synthase behaves like a trimer of dimeric units, each of the dimers behaving similarly to the B. megaterium and pig heart enzymes. Palmitoyl-CoA is required for the trypsinolysis of pig heart citrate synthase, and at relatively high concentrations of this compound trypsinolysis of one subunit leaves the other subunit fully active. Palmitoyl-CoA is not required for the trypsinolysis of the other citrate synthases, and high concentrations of this metabolite do not affect the correlation of proteolysis with inactivation of these enzymes.
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Affiliation(s)
- A J Else
- Department of Biochemistry, University of Bath, Claverton Down, U.K
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28
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Evans CT, Owens DD, Sumegi B, Kispal G, Srere PA. Isolation, nucleotide sequence, and expression of a cDNA encoding pig citrate synthase. Biochemistry 1988; 27:4680-6. [PMID: 3048387 DOI: 10.1021/bi00413a015] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Citrate synthase is a key enzyme of the Krebs tricarboxylic acid cycle and catalyzes the stereospecific synthesis of citrate from acetyl coenzyme A and oxalacetate. The amino acid sequence and three-dimensional structure of pig citrate synthase dimers are known, and regions of the enzyme involved in substrate binding and catalysis have been identified. A cloned complementary DNA sequence encoding pig citrate synthase has been isolated from a pig kidney lambda gt11 cDNA library after screening with a synthetic oligonucleotide probe. The complete nucleotide sequence of the 1.5-kilobase cDNA was determined. The coding region consists of 1395 base pairs and confirms the amino acid sequence of purified pig citrate synthase. The derived amino acid sequence of pig citrate synthase predicts the presence of a 27 amino acid N-terminal leader peptide whose sequence is consistent with the sequences of other mitochondrial signal peptides. A conserved amino acid sequence in the mitochondrial leader peptides of pig citrate synthase and yeast mitochondrial citrate synthase was identified. To express the pig citrate synthase cDNA in Escherichia coli, we employed the inducible T7 RNA polymerase/promoter double plasmid expression vectors pGP1-2 and pT7-7 [Tabor, S., & Richardson, C. C. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 1074-1078]. The pig citrate synthase cDNA was modified to delete the N-terminal leader sequence; then by use of a synthetic oligonucleotide linker, the modified cDNA was cloned into pT7-7 immediately following the initiator Met. A glutamate-requiring (citrate synthase deficient), recA- E. coli mutant, DEK15, was transformed with pGP1-2 and then pT7-7PCS. pT7-7PCS complemented the E. coli gltA mutation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C T Evans
- Pre-Clinical Science Unit, Veterans Administration Medical Center, Dallas, Texas 75216
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29
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Danson MJ. Archaebacteria: the comparative enzymology of their central metabolic pathways. Adv Microb Physiol 1988; 29:165-231. [PMID: 3132816 DOI: 10.1016/s0065-2911(08)60348-3] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- M J Danson
- Department of Biochemistry, University of Bath, England
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30
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Mitochondrial and nonmitochondrial citrate synthases in Saccharomyces cerevisiae are encoded by distinct homologous genes. Mol Cell Biol 1987. [PMID: 3540614 DOI: 10.1128/mcb.6.12.4509] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Saccharomyces cerevisiae contains two genes, CIT1 and CIT2, encoding functional citrate synthase (K.-S. Kim, M. S. Rosenkrantz, and L. Guarente, Mol. Cell. Biol. 6:1936-1942, 1986). We show here that CIT2 encodes a nonmitochondrial form of citrate synthase. The DNA sequence of CIT2 presented provides a possible explanation for why the CIT2 product, unlike the CIT1 product, fails to be imported into mitochondria. While the products of these two genes are highly homologous, they diverge strikingly at their amino termini. The amino terminus of the CIT1 primary translation product extends 39 residues beyond the amino termini of Escherichia coli and porcine citrate synthases. This extension consists of a typical mitochondrial targeting motif. The amino terminus of the CIT2 primary translation product extends 20 residues beyond the amino termini of the E. coli and porcine enzymes. The CIT2-encoded extension is not homologous to that of CIT1, resulting in a nonmitochondrial localization of the product. The CIT2-encoded extension, however, does bear certain similarities to mitochondrial targeting sequences. The possible role of this sequence in targeting this CIT2 product to a nonmitochondrial organelle is discussed.
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31
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Brent LG, Srere PA. The interaction of yeast citrate synthase with yeast mitochondrial inner membranes. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75929-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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32
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Rosenkrantz M, Alam T, Kim KS, Clark BJ, Srere PA, Guarente LP. Mitochondrial and nonmitochondrial citrate synthases in Saccharomyces cerevisiae are encoded by distinct homologous genes. Mol Cell Biol 1986; 6:4509-15. [PMID: 3540614 PMCID: PMC367235 DOI: 10.1128/mcb.6.12.4509-4515.1986] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Saccharomyces cerevisiae contains two genes, CIT1 and CIT2, encoding functional citrate synthase (K.-S. Kim, M. S. Rosenkrantz, and L. Guarente, Mol. Cell. Biol. 6:1936-1942, 1986). We show here that CIT2 encodes a nonmitochondrial form of citrate synthase. The DNA sequence of CIT2 presented provides a possible explanation for why the CIT2 product, unlike the CIT1 product, fails to be imported into mitochondria. While the products of these two genes are highly homologous, they diverge strikingly at their amino termini. The amino terminus of the CIT1 primary translation product extends 39 residues beyond the amino termini of Escherichia coli and porcine citrate synthases. This extension consists of a typical mitochondrial targeting motif. The amino terminus of the CIT2 primary translation product extends 20 residues beyond the amino termini of the E. coli and porcine enzymes. The CIT2-encoded extension is not homologous to that of CIT1, resulting in a nonmitochondrial localization of the product. The CIT2-encoded extension, however, does bear certain similarities to mitochondrial targeting sequences. The possible role of this sequence in targeting this CIT2 product to a nonmitochondrial organelle is discussed.
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33
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Hammond DC, Kruggel WG, Lewis RV, Barden RE. S-(4-bromo-2,3-dioxobutyl)-CoA labels two distinct sites on citrate synthase. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)83929-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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34
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McEvily AJ, Harrison JH. Subunit equilibria of porcine heart citrate synthase. Effects of enzyme concentration, pH, and substrates. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)35828-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Sakakibara R, Tanaka T, Uyeda K, Richards EG, Thomas H, Kangawa K, Matsuo H. Studies of the structure of fructose-6-phosphate 2-kinase:fructose-2,6-bisphosphatase. Biochemistry 1985; 24:6818-24. [PMID: 3000438 DOI: 10.1021/bi00345a013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Some physicochemical properties of a homogeneous preparation of a bifunctional enzyme, fructose-6-phosphate 2-kinase:fructose-2,6-bisphosphatase, were determined. The molecular weight of the enzyme is 101 000 as determined by high-speed sedimentation equilibrium. The molecular weight of dissociated enzyme is 55 000 in 6 M guanidinium chloride by sedimentation equilibrium and in sodium dodecyl sulfate by polyacrylamide gel electrophoresis. A value of 4.7 was observed for the isoelectric point. Tryptic peptide maps and high-performance liquid chromatography of the trypsin-digested enzyme revealed approximately 60 peptides. Amino acid analysis of the enzyme shows that it contains 27 lysine and 36 arginine residues per 55 000 daltons. No free N-terminal amino acid residue was detectable, suggesting that it is blocked. Hydrolysis of the enzyme by carboxypeptidases A and B releases tyrosine followed by histidine and arginine, indicating that the amino acid sequence at the carboxyl terminus is probably -Arg-His-Tyr. Tryptic digestion of [32P]phosphofructose-6-phosphate 2-kinase:fructose-2,6-bisphosphatase yields a 32P-labeled peptide detected by tryptic peptide mapping and high-performance liquid chromatography. Thermolysin digestion of CNBr-cleaved 32P-enzyme also yields a single 32P-peptide. These results indicate that fructose-6-phosphate 2-kinase:fructose-2,6-bisphosphatase is a dimer of 55 000 daltons and the subunits are very similar, if not identical.
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36
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Buck D, Spencer ME, Guest JR. Primary structure of the succinyl-CoA synthetase of Escherichia coli. Biochemistry 1985; 24:6245-52. [PMID: 3002435 DOI: 10.1021/bi00343a031] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The primary structure of the succinyl-CoA synthetase of Escherichia coli has been deduced from the nucleotide sequence of a 2451-base-pair segment of DNA containing the corresponding sucC (beta subunit) and sucD (alpha subunit) genes. The genes are located at one end of a gene cluster that encodes several citric acid cycle enzymes: gltA-sdhCDAB-sucABCD; gltA, citrate synthase; sdh, succinate dehydrogenase; sucA and sucB, the dehydrogenase (E1) and succinyltransferase (E2) components of the 2-oxoglutarate dehydrogenase complex. The sucC and sucD genes are separated from the sucA and sucB genes by a 273-base-pair segment containing four palindromic units, but they appear to be expressed from a sucABCD read-through transcript that extends from the suc promoter to a potential rho-independent terminator at the distal end of sucD. The stop codon of the sucC gene overlaps the sucD initiation codon by a single nucleotide, indicating close translational coupling of the sucC and sucD genes. The sucC gene comprises 1161 base pairs (388 codons, excluding the stop codon), and it encodes a polypeptide of Mr 41 390 corresponding to the beta subunit of succinyl-CoA synthetase. The sucD gene comprises 864 base pairs (288 codons, excluding the start and stop codons), and it encodes a product of Mr 29 644, corresponding to the alpha subunit of succinyl-CoA synthetase. The alpha subunit contains a 12-residue amino acid sequence that is identical with the histidine peptide previously isolated from the phosphoenzyme. This sequence forms part of one of the two potential nucleotide binding sites detected in the alpha subunit.
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37
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Regulation of aminotransferase-glutamate dehydrogenase interactions by carbamyl phosphate synthase-I, Mg2+ plus leucine versus citrate and malate. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)88939-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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38
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Lill U, Schreil A, Henschen A, Eggerer H. Hysteretic behaviour of citrate synthase. Site-directed limited proteolysis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 143:205-12. [PMID: 6381053 DOI: 10.1111/j.1432-1033.1984.tb08360.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Limited proteolysis of citrate synthase by Astacus protease, chymotrypsin, clostripain, subtilisin and trypsin on primary fragmentation all yielded similarly sized large (Mr 35 000-36 000) and small fragments (Mr 13 500-14 000) but endoproteinase Lys-C gave fragments of Mr 40 500 and Mr 6500. The sites of the proteolytic attack were determined by Edman degradation of the fragmented synthase preparations, Chymotrypsin, subtilisin, trypsin and endoproteinase Lys-C hydrolyse the synthase at positions 323-324 (-Leu-Arg-), 321-322 (-Ala-Val-)/322-323 (-Val-Leu-), 313-314 (-Arg-Val-) and 366-367 (-Lys-Ala-), respectively. Chymotrypsin and subtilisin attack the small domain of the synthase at the loop between helices O and P very near to a catalytic residue, His-320, and abolish all synthase activities. Primary fragmentation by endoproteinase Lys-C and trypsin reduces the catalytic activity in the physiological overall reaction. Both fragmented enzyme species catalyse the hydrolysis and C-C bond cleavage reactions of citryl-CoA in a stimulated fashion compared to the steady-state rates of the native enzyme, and without hysteretic behaviour. The proteolytic cleavage occurs at acetyl-CoA binding sites within the small domain at the loops connecting helices O to P (trypsin) and Q to R (endoproteinase Lys-C) and reduces the affinity of acetyl-CoA. All of the altered kinetic properties of the fragmented enzyme species are related to this reduced affinity. The correlation between structure and function indicated above is strengthened by the unaltered affinity of oxaloacetate towards the fragmented synthase species. None of the proteolytic enzymes applied attacks oxaloacetate binding sites as defined by the structural work. Oxaloacetate inhibits the hydrolysis of citryl-CoA by the fragmented synthases (endoproteinase Lys-C, trypsin) competitively. An explanation is proposed. The isolated small and large fragments (endoproteinase Lys-C, trypsin) were enzymically inactive. Enzymic activity was restored on recombination of the fragments under denaturing conditions. Cleavage of the loops between helices O to P and Q to R by sequential fragmentation with endoproteinase Lys-C and trypsin inactivated the synthase completely. This result lends support to the idea that the open and closed crystal forms of the structural work are interconverted during the catalytic cycle.
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39
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Ghrir R, Becam AM, Lederer F. Primary structure of flavocytochrome b2 from baker's yeast. Purification by reverse-phase high-pressure liquid chromatography and sequencing of fragment alpha cyanogen bromide peptides. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 139:59-74. [PMID: 6365548 DOI: 10.1111/j.1432-1033.1984.tb07976.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Reverse-phase high-pressure liquid chromatography has been used for the purification of some large cyanogen bromide peptides from flavocytochrome b2 fragment alpha. Acetonitrile gradients at acid and/or neutral pH using mu Bondapak C18 columns were useful for the smaller peptides (43 and 67 residues). The two larger ones, alpha CB1 and alpha CB2, could only be separated from each other by trifluoroacetic acid/1-propanol gradients on mu Bondapak-CN columns. The various systems tested are presented and compared. The elucidation of the amino acid sequence of alpha CB2 (95 residues), alpha CB3 (67 residues) and alpha CB4 (43 residues) is described. The fragments were digested with trypsin, chymotrypsin and Staphylococcus aureus V8 protease as necessary. Fragment alpha CB2 was also cleaved at the unique tryptophanyl bond with cyanogen bromide. Peptides were fractionated by Sephadex chromatography, thin-layer finger-printing and/or high-pressure liquid chromatography. Peptides were sequenced mostly in the liquid phase sequenator. The cyanogen bromide peptides could be ordered using information obtained previously, as well as additional data obtained in this work. Together with the previous elucidation of cytochrome b2 core sequence and of the hinge region [Guiard, B. and Lederer, F. (1976) Biochimie (Paris) 58, 305--316; Ghrir, R. and Lederer, F. (1981) Eur. J. Biochem. 120, 279--287], the present results enable us to present the complete sequence of fragment alpha (314 residues) with only three overlaps missing between cyanogen bromide peptides. Sequence comparisons with other known flavoproteins do not indicate any noticeable similarity. Structural predictions indicate an alteration of alpha helices and beta structure. The possibility that the non-heme-binding portion of fragment alpha could constitute a flavin-binding domain is discussed.
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40
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Hansel BC, Powell GL. Regulation of enzymes by fatty acyl coenzyme A. Interactions of short and long chain spin-labeled acyl-CoA with the acetyl-CoA site on pig heart citrate synthase. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43423-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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41
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Löhlein-Werhahn G, Bayer E, Bauer B, Eggerer H. Hysteretic behaviour of citrate synthase. Alternating sites during the catalytic cycle. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 133:665-72. [PMID: 6861748 DOI: 10.1111/j.1432-1033.1983.tb07515.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Chemically and stereochemically pure (3S)-citryl-CoA was prepared enzymically and used as a substrate for citrate synthase to investigate the previously determined unexpectedly low rate of hydrolysis of the (3RS)-substrate. The unnatural R-diastereomer of this mixture is not inhibitory. At low enzyme concentrations the rate of citryl-CoA hydrolysis was linear until the reaction went near to completion; the hydrolysis approached Michaelis-Menten kinetics at high enzyme concentrations. In between these concentration extremes a biphasic rate dependence was detectable, where a fast initial phase lasting a few seconds was followed by a slow steady-state phase. Citrate synthase was characterized as a hysteretic enzyme existing in two interconvertible forms, which were designated according to their functions as hydrolase E and ligase E'. The hysteretic behaviour originates in the cleavage of citryl-CoA to acetyl-CoA and oxaloacetate. This reaction occurs on the ligase form E', which represents a trap for enzyme form E, the hydrolase. The conclusions given above are strengthened by the ordinary hydrolysis kinetics of (2S)-malyl-CoA, a substrate that is not subject to cleavage of the C-C bond on the synthase. The results satisfy the kinetic criterion for citryl-CoA being an intermediate of the physiological synthase reaction and, therefore, establish the oscillation of the synthase between hydrolase and ligase states during the catalytic cycle. A disorganization of these oscillations can be achieved by limited tryptic proteolysis of the synthase.
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Robinson MS, Danson MJ, Weitzman PD. Citrate synthase from a Gram-positive bacterium. Purification and characterization of the Bacillus megaterium enzyme. Biochem J 1983; 213:53-9. [PMID: 6412681 PMCID: PMC1152089 DOI: 10.1042/bj2130053] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Citrate synthase was purified to homogeneity from a Gram-positive bacterium (Bacillus megaterium) for the first time. The Mr of the native enzyme was determined to be 84 000 (S.E.M. +/- 5000). Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and gel filtration in guanidinium chloride revealed a single protein species of Mr 40 300 (S.E.M. +/- 4400), indicating a dimeric enzyme. This dimeric structure was confirmed by cross-linking the native enzyme with dimethyl suberimidate and with glutaraldehyde, followed by electrophoretic analysis. The enzyme follows Michaelis-Menten kinetics with respect to both substrates, acetyl-CoA and oxaloacetate, and is sensitive to non-specific inhibition by a range of adenine nucleotides. In both molecular and catalytic properties the citrate synthase closely resembles the enzyme from eukaryotic sources and contrasts markedly with the larger, hexameric, enzyme from Gram-negative bacteria.
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Prediction of peptide retention times in reversed-phases high-performance liquid chromatography during linear gradient elution. J Chromatogr A 1982. [DOI: 10.1016/s0021-9673(00)99612-2] [Citation(s) in RCA: 134] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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