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Hinson DD, Ross RM, Krisans S, Shaw JL, Kozich V, Rolland MO, Divry P, Mancini J, Hoffmann GF, Gibson KM. Identification of a mutation cluster in mevalonate kinase deficiency, including a new mutation in a patient of Mennonite ancestry. Am J Hum Genet 1999; 65:327-35. [PMID: 10417275 PMCID: PMC1377931 DOI: 10.1086/302489] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Mevalonate kinase (MKase) deficiency (MKD) is a rare autosomal recessive disorder in the pathway of cholesterol and nonsterol isoprenoid biosynthesis. Thus far, two disease-causing missense alleles have been identified, N301T and A334T. We report four additional mutations associated with MKD: L264F, T243I, L265P, and I268T, the last found in a patient of Mennonite ancestry. Electrophoretic analysis of bacterially expressed wild-type and mutant MKase indicated that I268T and T243I mutants produced normal or somewhat reduced amounts of MKase protein; conversely, L264F and L265P mutations resulted in considerably decreased, or absent, MKase protein. Immunoblot analysis of MKase from all patients suggested that the MKase polypeptide was grossly intact and produced in amounts comparable to control levels. Three mutations resulted in significantly diminished MKase enzyme activity (<2%), whereas the I268T allele yielded approximately 20% residual enzyme activity. Our results should allow more-accurate identification of carriers and indicate a mutation "cluster" within amino acids 240-270 of the mature MKase polypeptide.
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Affiliation(s)
- D D Hinson
- Institute of Metabolic Disease, Baylor University Medical Center, Dallas, TX, USA
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Hinson DD, Chambliss KL, Hoffmann GF, Krisans S, Keller RK, Gibson KM. Identification of an active site alanine in mevalonate kinase through characterization of a novel mutation in mevalonate kinase deficiency. J Biol Chem 1997; 272:26756-60. [PMID: 9334262 DOI: 10.1074/jbc.272.42.26756] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Sequencing of polymerase chain reaction-amplified cDNAs from cultured cells of three patients with mevalonate kinase deficiency revealed a G --> A transversion at nucleotide 1000 of the coding region, converting alanine to threonine at position 334 (A334T). To characterize this defect, we expressed wild-type and mutant cDNAs in Escherichia coli as the glutathione S-transferase fusion proteins, with purification by affinity chromatography. SDS-polyacrylamide gel electrophoresis analysis for wild-type and mutant fusion proteins indicated an expected molecular mass of 42-43 kDa. Kinetic characterization of the wild-type fusion protein yielded Km values of 150 +/- 23 and 440 +/- 190 microM (mean +/- S.E.) for substrates (RS)-mevalonate and ATP, respectively. Expressed wild-type mevalonate kinase (MKase) had a maximum velocity of 13.6 +/- 1.4 units/mg of protein (n = 22, +/-S.E.), whereas the A334T mutation yielded an enzyme with average Vmax of 0.26 +/- 0.02 unit/mg of protein (n = 6, +/-S.E.), representing a decrease to 1.4% of control Vmax. Restriction digestion with HhaI, in conjunction with direct sequencing of cDNAs, revealed that two patients were homozygous and one heterozygous for the A334T allele, establishing autosomal recessive inheritance within families. Although the A334T enzyme had a normal Km for ATP of 680 +/- 226 microM (n = 3, +/-S.E.), the Michaelis constant for (RS)-mevalonate was increased >30-fold to 4623 +/- 1167 microM (n = 4, +/-S.E.) under standard assay conditions. Comparable kinetic results were obtained using extracts of lymphoblasts, which were homozygous for the A334T allele. Alanine 334 is invariant in MKase from bacteria to man and located in a glycine-rich region postulated to have homology with ATP-binding sequences. Our results indicate that the bacterial expression system for human MKase will provide a useful model system in which to analyze inherited mutations and identify the first active site residue in MKase associated with stabilization of mevalonate binding.
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Affiliation(s)
- D D Hinson
- Institute of Metabolic Disease, Baylor University Medical Center, Dallas, Texas 75226, USA
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Keller GA, Krisans S, Gould SJ, Sommer JM, Wang CC, Schliebs W, Kunau W, Brody S, Subramani S. Evolutionary conservation of a microbody targeting signal that targets proteins to peroxisomes, glyoxysomes, and glycosomes. J Biophys Biochem Cytol 1991; 114:893-904. [PMID: 1831458 PMCID: PMC2289121 DOI: 10.1083/jcb.114.5.893] [Citation(s) in RCA: 140] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Peroxisomes, glyoxysomes, glycosomes, and hydrogenosomes have each been classified as microbodies, i.e., subcellular organelles with an electron-dense matrix that is bound by a single membrane. We investigated whether these organelles might share a common evolutionary origin by asking if targeting signals used for translocation of proteins into these microbodies are related. A peroxisomal targeting signal (PTS) consisting of the COOH-terminal tripeptide serine-lysine-leucine-COOH has been identified in a number of peroxisomal proteins (Gould, S.J., G.-A. Keller, N. Hosken, J. Wilkinson, and S. Subramani. 1989. J. Cell Biol. 108:1657-1664). Antibodies raised to a peptide ending in this sequence (SKL-COOH) recognize a number of peroxisomal proteins. Immunocryoelectron microscopy experiments using this anti-SKL antibody revealed the presence of proteins containing the PTS within glyoxysomes of cells from Pichia pastoris, germinating castor bean seeds, and Neurospora crassa, as well as within the glycosomes of Trypanosoma brucei. Western blot analysis of purified organelle fractions revealed the presence of many proteins containing this PTS in both glyoxysomes and glycosomes. These results indicate that at least one of the signals, and therefore the mechanism, for protein translocation into peroxisomes, glyoxysomes, and glycosomes has been conserved, lending support to a common evolutionary origin for these microbodies. Hydrogenosomes, the fourth type of microbody, did not contain proteins that cross-reacted with the anti-PTS antibody, suggesting that this organelle is unrelated to microbodies.
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Affiliation(s)
- G A Keller
- Department of Preclinical Pharmacology, Genentech Inc., South San Francisco, California 94080
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Hamilton RL, Wong JS, Guo LS, Krisans S, Havel RJ. Apolipoprotein E localization in rat hepatocytes by immunogold labeling of cryothin sections. J Lipid Res 1990. [DOI: 10.1016/s0022-2275(20)42343-0] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Hamilton RL, Wong JS, Guo LS, Krisans S, Havel RJ. Apolipoprotein E localization in rat hepatocytes by immunogold labeling of cryothin sections. J Lipid Res 1990; 31:1589-603. [PMID: 2246612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The distribution of apolipoprotein (apo) E in rat hepatocytes was investigated with an affinity-purified polyclonal antibody raised against apoE isolated from hepatogeneous very low density lipoproteins (VLDL). The distribution of this antibody was visualized with colloidal gold complexed to anti-rabbit IgG. By epipolarization microscopy, apoE was found uniformly along the basolateral surfaces of all hepatic parenchymal cells, showing a striking intensity along the sinusoidal front. Punctate deposits of colloidal gold appeared to be randomly distributed within all hepatocytes. Widely scattered Kupffer cells also stained for apoE. Electron microscopic examination of immunogold-labeled cryothin sections showed that hepatocytic microvilli projecting into the space of Disse consistently contained clusters of immunogold. The gold particles were variably associated with evident lipoprotein particles, raising the possibility that apoE alone may bind to receptors or other macromolecules at the surface of hepatocytes. Endosomes near the sinusoidal front and multivesicular bodies in the Golgi/biliary area labeled intensely for apoE, consistent with a high content of apoE associated with triglyceride-rich lipoprotein remnants contained within these organelles. Some but not all nascent VLDL particles within putative forming Golgi secretory vesicles were labeled, but many other Golgi vesicles and cisternae that lacked evident VLDL particles were also labeled. These results suggest that at least some apoE associates with nascent VLDL in forming Golgi secretory vesicles. Unexpectedly, the matrix of all hepatocytic peroxisomes was heavily labeled. Immunoblots with the affinity-purified anti-rat apoE IgG against proteins from highly purified peroxisomes isolated from rat hepatocytes revealed a protein with an apparent molecular mass of 34.5 kDa, similar to that of rat apoE in rat blood plasma. In addition, gold was sometimes found in the area either adjacent to peroxisomes or between multivesicular bodies and the bile canaliculus not evidently associated with a membranous compartment. These observations suggest that apoE may participate in interorganellar cholesterol transport within hepatocytes.
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Affiliation(s)
- R L Hamilton
- Department of Anatomy, University of California, San Francisco 94143-0130
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Gould SJ, Krisans S, Keller GA, Subramani S. Antibodies directed against the peroxisomal targeting signal of firefly luciferase recognize multiple mammalian peroxisomal proteins. J Cell Biol 1990; 110:27-34. [PMID: 1688562 PMCID: PMC2115984 DOI: 10.1083/jcb.110.1.27] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We have previously shown that the peroxisomal targeting signal in firefly luciferase consists of the COOH-terminal three amino acids of the protein, serine-lysine-leucine (Gould, S.J., G.A. Keller, N. Hosken, J. Wilkinson, and S. Subramani, 1989. J. Cell Biol. 108:1657-1664). Antibodies were raised against a synthetic peptide that contained this tripeptide at its COOH terminus. Immunofluorescence and immunocryoelectron microscopy revealed that the anti-peptide antibodies specifically detected peroxisomes in mammalian cells. Further characterization revealed that the antibodies were primarily directed against the COOH-terminal three amino acids of the peptide. In Western blot experiments, the antibodies recognized 15-20 rat liver peroxisomal proteins, but reacted with only a few proteins from other subcellular compartments. These results provide independent immunological evidence that the peroxisomal targeting signal identified in firefly luciferase is present in many peroxisomal proteins.
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Affiliation(s)
- S J Gould
- Department of Biology, University of California, La Jolla 92093
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Gutierrez C, Okita R, Krisans S. Demonstration of cytochrome reductases in rat liver peroxisomes: biochemical and immunochemical analyses. J Lipid Res 1988. [DOI: 10.1016/s0022-2275(20)38504-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Gutierrez C, Okita R, Krisans S. Demonstration of cytochrome reductases in rat liver peroxisomes: biochemical and immunochemical analyses. J Lipid Res 1988; 29:613-28. [PMID: 3137303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In this study we utilized the analytical cell fractionation approach in combination with immunoblotting techniques and immunoelectron microscopy to test for the presence of NADPH cytochrome P-450 reductase and NADH cytochrome c (b5) reductase in rat liver peroxisomes. Highly purified peroxisomes from clofibrate-treated rats exhibited both NADPH cytochrome P-450 reductase activity and NADH cytochrome c reductase activity (using cytochrome c as an electron acceptor). These activities were inhibited by the respective reductase antibodies made against the endoplasmic reticulum (ER) enzymes. Immunoblot data in combination with immunoelectron microscopy indicated that the peroxisomal NADPH cytochrome P-450 reductase is localized in the matrix of the organelle and has a subunit of molecular weight similar to that of the ER enzyme, whereas the NADH cytochrome c (b5) reductase is localized in the membranes of the peroxisomes. Again, the subunit molecular weight was similar to that of the ER enzyme. The presence of these reductases in peroxisomes further supports the role of this organelle in bile acid synthesis and cholesterol metabolism.
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Affiliation(s)
- C Gutierrez
- Department of Biology, San Diego State University, CA 92182
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Keller GA, Pazirandeh M, Krisans S. 3-Hydroxy-3-methylglutaryl coenzyme A reductase localization in rat liver peroxisomes and microsomes of control and cholestyramine-treated animals: quantitative biochemical and immunoelectron microscopical analyses. J Biophys Biochem Cytol 1986; 103:875-86. [PMID: 3745272 PMCID: PMC2114277 DOI: 10.1083/jcb.103.3.875] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, a key regulatory enzyme involved in cholesterol biosynthesis, has recently been reported to be present in rat liver peroxisomes (Keller, G.A., M.C. Barton, D.J. Shapiro, and S.J. Singer, 1985, Proc. Natl. Acad. Sci. USA, 82:770-774). Immunoelectron labeling of ultrathin frozen sections of normal liver, using two monoclonal antibodies to purified rat liver microsomal HMG-CoA reductase, indicated that the enzyme is present in the matrix of peroxisomes. This study is a quantitative biochemical and immunoelectron microscopical analysis of HMG-CoA reductase in rat liver peroxisomes and microsomes of normal and cholestyramine-treated animals. Cholestyramine treatment produced a six- to sevenfold increase in the specific activity of peroxisomal HMG-CoA reductase, whereas the microsomal HMG-CoA reductase specific activity increased by about twofold. Using a computer program that calculates optimal linear combinations of marker enzymes, it was determined that between 20 and 30% of the total reductase activity was located in the peroxisomes of cholestyramine-treated animals. Less than 5% of the reductase activity was present in peroxisomes under control conditions. Quantitation of the immunoelectron microscopical data was in excellent agreement with the biochemical results. After cholestyramine treatment there was an eightfold increase in the density of gold particles per peroxisome, and we estimate about a threefold increase in the labeling of the ER.
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Somanathan R, Krisans S. Synthesis of C-22, C-23-3H-labeled 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestane. J Lipid Res 1985; 26:774-5. [PMID: 4031656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
This report describes an efficient synthesis of C-22, C-23-(3)H-labeled 3alpha,7alpha,12alpha-trihydroxy-5beta-cholestane. - Somanathan, R., and S. Krisans. Synthesis of C-22, C-23-(3)H-labeled 3alpha,7alpha,12alpha-trihydroxy-5beta-cholestane.
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Somanathan R, Krisans S. Synthesis of C-22, C-23-3H-labeled 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestane. J Lipid Res 1985. [DOI: 10.1016/s0022-2275(20)34336-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Abstract
Synthesis of a mixture of the 25(R) and 25(S) isomers of 5 beta-cholestane-3 alpha,7 alpha,12 alpha, 26(27)-tetrol from cholic acid in four steps, including a Wittig reaction, is described.
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