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D'Aniello S, Delroisse J, Valero-Gracia A, Lowe EK, Byrne M, Cannon JT, Halanych KM, Elphick MR, Mallefet J, Kaul-Strehlow S, Lowe CJ, Flammang P, Ullrich-Lüter E, Wanninger A, Arnone MI. Opsin evolution in the Ambulacraria. Mar Genomics 2015; 24 Pt 2:177-83. [PMID: 26472700 DOI: 10.1016/j.margen.2015.10.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 10/02/2015] [Accepted: 10/02/2015] [Indexed: 11/16/2022]
Abstract
Opsins--G-protein coupled receptors involved in photoreception--have been extensively studied in the animal kingdom. The present work provides new insights into opsin-based photoreception and photoreceptor cell evolution with a first analysis of opsin sequence data for a major deuterostome clade, the Ambulacraria. Systematic data analysis, including for the first time hemichordate opsin sequences and an expanded echinoderm dataset, led to a robust opsin phylogeny for this cornerstone superphylum. Multiple genomic and transcriptomic resources were surveyed to cover each class of Hemichordata and Echinodermata. In total, 119 ambulacrarian opsin sequences were found, 22 new sequences in hemichordates and 97 in echinoderms (including 67 new sequences). We framed the ambulacrarian opsin repertoire within eumetazoan diversity by including selected reference opsins from non-ambulacrarians. Our findings corroborate the presence of all major ancestral bilaterian opsin groups in Ambulacraria. Furthermore, we identified two opsin groups specific to echinoderms. In conclusion, a molecular phylogenetic framework for investigating light-perception and photobiological behaviors in marine deuterostomes has been obtained.
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Affiliation(s)
- S D'Aniello
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy.
| | - J Delroisse
- Biology of Marine Organisms and Biomimetics, Research Institute for Biosciences, University of Mons, Avenue du Champs de Mars 6, 7000 Mons, Belgium; School of Biological & Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - A Valero-Gracia
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - E K Lowe
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA
| | - M Byrne
- Schools of Medical and Biological Sciences, The University of Sydney, Sydney, NSW, Australia
| | - J T Cannon
- Department of Biological Sciences and Molette Biology Laboratory for Environmental and Climate Change Studies, Auburn University, Auburn, USA; Department of Zoology, Naturhistoriska Riksmuseet, Stockholm, Sweden; Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
| | - K M Halanych
- Department of Biological Sciences and Molette Biology Laboratory for Environmental and Climate Change Studies, Auburn University, Auburn, USA
| | - M R Elphick
- School of Biological & Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - J Mallefet
- Laboratory of Marine Biology, Earth and Life Institute, Université Catholique de Louvain, Louvain-La-Neuve, Place Croix du Sud 3, bt L7.06.04, 1348 Louvain-la-Neuve, Belgium
| | - S Kaul-Strehlow
- Department of Molecular Evolution and Development, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - C J Lowe
- Hopkins Marine Station of Stanford University, Pacific Grove, CA 93950, USA
| | - P Flammang
- Biology of Marine Organisms and Biomimetics, Research Institute for Biosciences, University of Mons, Avenue du Champs de Mars 6, 7000 Mons, Belgium
| | - E Ullrich-Lüter
- Museum fuer Naturkunde Berlin, Invalidenstr 43, 10115 Berlin, Germany
| | - A Wanninger
- Department of Integrative Zoology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - M I Arnone
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
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2
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Abstract
The CyIIa gene of the sea urchin embryo is a model for study of cis-regulation downstream of cell-type specification, as CyIIa transcription follows the specification and initial differentiation of the embryonic domains in which it is expressed. These are the skeletogenic and secondary mesenchyme and gut. We carried out a detailed structural and functional analysis of a cis-regulatory region of this gene, extending 780 bp upstream and 125 bp downstream of the transcription start site, that had been shown earlier to reproduce faithfully the complex and dynamic CyIIa pattern of expression. This analysis revealed that the overall pattern of expression of the CyIIa gene appears to be governed mainly by two independent sets of DNA elements, which are target sites for specific proteins present in blastula-stage nuclear extract. One type of element, which controls a dynamic program of expression in both skeletogenic and secondary mesenchyme cells, contains the consensus-binding site for a member of the ets transcription factor family. The other, which is responsible for the terminal or permanent phase of CyIIa expression in the gut, shares homologies with the late module of the endoderm-specific Endo16 gene (endo16 Module B). Oligonucleotides containing replicas of these two target sites fused upstream of a sea urchin basal promoter are sufficient to confer accurate mesenchyme and late gut expression of an injected GFP construct. The finding of a single protein target site that recapitulates CyIIa expression in both primary and secondary mesenchyme cells suggests the existence of a pan-mesodermal gene expression program in the sea urchin embryo.
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Affiliation(s)
- E L Martin
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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3
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Bogarad LD, Arnone MI, Chang C, Davidson EH. Interference with gene regulation in living sea urchin embryos: transcription factor knock out (TKO), a genetically controlled vector for blockade of specific transcription factors. Proc Natl Acad Sci U S A 1998; 95:14827-32. [PMID: 9843974 PMCID: PMC24534 DOI: 10.1073/pnas.95.25.14827] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
"TKO" is an expression vector that knocks out the activity of a transcription factor in vivo under genetic control. We describe a successful test of this concept that used a sea urchin transcription factor of known function, P3A2, as the target. The TKO cassette employs modular cis-regulatory elements to express an encoded single-chain antibody that prevents the P3A2 protein from binding DNA in vivo. In normal development, one of the functions of the P3A2 transcription factor is to repress directly the expression of the CyIIIa cytoskeletal actin gene outside the aboral ectoderm of the embryo. Ectopic expression in oral ectoderm occurs if P3A2 sites are deleted from CyIIIa expression constructs, and we show here that introduction of an alphaP3A2.TKO expression cassette causes exactly the same ectopic oral expression of a coinjected wild-type CyIIIa construct. Furthermore, the alphaP3A2.TKO cassette derepresses the endogenous CyIIIa gene in the oral ectoderm and in the endoderm. alphaP3A2.TKO thus abrogates the function of the endogenous SpP3A2 transcription factor with respect to spatial repression of the CyIIIa gene. Widespread expression of alphaP3A2.TKO in the endoderm has the additional lethal effect of disrupting morphogenesis of the archenteron, revealing a previously unsuspected function of SpP3A2 in endoderm development. In principle, TKO technology could be utilized for spatially and temporally controlled blockade of any transcription factor in any biological system amenable to gene transfer.
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Affiliation(s)
- L D Bogarad
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
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4
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Arnone MI, Martin EL, Davidson EH. Cis-regulation downstream of cell type specification: a single compact element controls the complex expression of the CyIIa gene in sea urchin embryos. Development 1998; 125:1381-95. [PMID: 9502720 DOI: 10.1242/dev.125.8.1381] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
CyIIa, a cytoskeletal actin gene of Strongylocentrotus purpuratus, is expressed specifically though transiently in the embryonic skeletogenic and secondary mesenchyme and, later in development, is permanently activated in the hindgut and midgut. CyIIa transcription follows, and is therefore downstream of, the initial specification of these embryonic domains. A detailed functional analysis of the cis-regulatory system governing the rate and the location of CyIIa expression during development was carried out using GFP expression constructs. About 4.4 kb of CyIIa sequence including a leader intron were examined for cis-regulatory function. Distal elements scattered over several kb account for 60% of the quantitative output of the expression construct and a strong amplifier of expression is located within the leader intron. However, the complex spatial pattern of CyIIa expression is completely reproduced by a compact upstream regulatory element <450 bp in length. We found no evidence anywhere in the 4.4 kb sequence examined for negative regulators required to repress ectopic expression. The specific site that mediates CyIIa expression in the midgut in late embryos and larvae was identified. This site is the same as that necessary and sufficient for midgut expression of the Endo16 gene late in development, and was shown to bind the same transcription factor. Except for some temporal and quantitative features, the S. purpuratus expression construct is expressed accurately and specifically in the same diverse cell types when introduced into embryos of Lytechinus pictus, which belongs to a different echinoid order. No ectopic expression was observed, in contrast to the result of a similar interspecific gene transfer experiment carried out earlier on a different cytoskeletal actin gene that is expressed much earlier in development. Presentation of the set of transcription factors that activate CyIIa in the differentiated cells in which it is expressed is apparently a conserved feature of these cell types.
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Affiliation(s)
- M I Arnone
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
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5
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Arnone MI, Bogarad LD, Collazo A, Kirchhamer CV, Cameron RA, Rast JP, Gregorians A, Davidson EH. Green Fluorescent Protein in the sea urchin: new experimental approaches to transcriptional regulatory analysis in embryos and larvae. Development 1997; 124:4649-59. [PMID: 9409681 DOI: 10.1242/dev.124.22.4649] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [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: 11/20/2022]
Abstract
The use of Green Fluorescent Protein (GFP) as a reporter for expression transgenes opens the way to several new experimental strategies for the study of gene regulation in sea urchin development. A GFP coding sequence was associated with three different previously studied cis-regulatory systems, viz those of the SM50 gene, expressed in skeletogenic mesenchyme, the CyIIa gene, expressed in archenteron, skeletogenic and secondary mesenchyme, and the Endo16 gene, expressed in vegetal plate, archenteron and midgut. We demonstrate that the sensitivity with which expression can be detected is equal to or greater than that of whole-mount in situ hybridization applied to detection of CAT mRNA synthesized under the control of the same cis-regulatory systems. However, in addition to the important feature that it can be visualized nondestructively in living embryos, GFP has other advantages. First, it freely diffuses even within fine cytoplasmic cables, and thus reveals connections between cells, which in sea urchin embryos is particularly useful for observations on regulatory systems that operate in the syncytial skeletogenic mesenchyme. Second, GFP expression can be dramatically visualized in postembryonic larval tissues. This brings postembryonic larval developmental processes for the first time within the easy range of gene transfer analyses. Third, GFP permits identification and segregation of embryos in which the clonal incorporation of injected DNA has occurred in any particular desired region of the embryo. Thus, we show explicitly that, as expected, GFP transgenes are incorporated in the same nuclei together with other transgenes with which they are co-injected.
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Affiliation(s)
- M I Arnone
- Division of Biology and Stowers Institute for Medical Research, California Institute of Technology, Pasadena 91125, USA
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6
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Zannini M, Avantaggiato V, Biffali E, Arnone MI, Sato K, Pischetola M, Taylor BA, Phillips SJ, Simeone A, Di Lauro R. TTF-2, a new forkhead protein, shows a temporal expression in the developing thyroid which is consistent with a role in controlling the onset of differentiation. EMBO J 1997; 16:3185-97. [PMID: 9214635 PMCID: PMC1169936 DOI: 10.1093/emboj/16.11.3185] [Citation(s) in RCA: 171] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Expression of thyroglobulin (Tg) and thyroperoxidase (TPO) genes in thyroid follicular cells occurs in the mouse at embryonic day (E)14.5. Two transcription factors, TTF-1 and Pax-8, have been implicated in transcriptional activation of Tg and TPO, even though the onset of their expression is at E9.5, suggesting that additional events are necessary for transcriptional activation of Tg and TPO genes. We report in this paper the cloning of TTF-2, a DNA binding protein that recognizes sites on both Tg and TPO promoters. TTF-2 is a new forkhead domain-containing protein whose expression is restricted to the endodermal lining of the foregut and to the ectoderm that will give rise to the anterior pituitary. TTF-2 shows transient expression in the developing thyroid and anterior pituitary. In the thyroid, TTF-2 expression is down-regulated just before the onset of Tg and TPO gene expression, suggesting that this transcription factor plays the role in development of a negative controller of thyroid-specific gene expression.
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Affiliation(s)
- M Zannini
- Stazione Zoologica A. Dohrn, Napoli, Italy
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7
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Abstract
The gene regulatory apparatus that directs development is encoded in the DNA, in the form of organized arrays of transcription factor target sites. Genes are regulated by interactions with multiple transcription factors and the target sites for the transcription factors required for the control of each gene constitute its cis-regulatory system. These systems are remarkably complex. Their hardwired internal organization enables them to behave as genomic information processing systems. Developmental gene regulatory networks consist of the cis-regulatory systems of all the relevant genes and the regulatory linkages amongst them. Though there is yet little explicit information, some general properties of genomic regulatory networks have become apparent. The key to understanding how genomic regulatory networks are organized, and how they work, lies in experimental analysis of cis-regulatory systems at all levels of the regulatory network.
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Affiliation(s)
- M I Arnone
- Stowers Institute for Medical Research, Division of Biology, California Institute of Technology, Pasadena 91125, USA
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8
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Arnone MI, Birolo L, Pascarella S, Cubellis MV, Bossa F, Sannia G, Marino G. Stability of aspartate aminotransferase from Sulfolobus solfataricus. Protein Eng 1997; 10:237-48. [PMID: 9153089 DOI: 10.1093/protein/10.3.237] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Aspartate aminotransferase from Sulfolobus solfataricus (SsAspAT) is an extremely thermophilic and thermostable dimeric enzyme which retains its structure and reaches maximal activity at 100 degrees C. The structural stability of this protein was investigated by coupling isothermally and thermally induced denaturation studies to molecular modeling. Gel filtration analysis indicated that SsAspAT unfolds with an N2 reversible 2D mechanism. In the molecular model, a cluster of hydrophobic residues was shown at the interface between the subunits of SsAspAT and suggested this cluster as a structural feature stabilizing the enzyme quaternary structure. At 25 degrees C, SsAspAT is less resistant to guanidinium chloride-induced denaturation than the cytosolic aspartate aminotransferase from pig heart (cpAspAT), which was chosen as a mesophilic counterpart in the thermodynamic analysis since it shares with SsAspAT the two-state unfolding mechanism. Therefore, in the case of aspartate aminotransferases, thermal stability does not correlate with the stability against chemical denaturants. Isothermal denaturation curves at 25 degrees C and melting profiles recorded in the presence of guanidinium chloride showed that the delta G degrees (H2O) at 25 degrees C of SsAspAT exceeds that of cpAspAT by roughly 15 kJ/mol; the parameter delta n, related to the number of binding sites for the denaturant differentially exposed in unfolded and folded states, is higher for SsAspAT than for cpAspAT; and delta Cp is lower for the thermophilic enzyme than for the mesophilic one by 8 kJ/K.mol. These results are indicative of a less hydrophobic core for SsAspAT than cpAspAT. In agreement with this, the molecular model predicts that some charged side chains are buried in SsAspAT and interact to form an H-bond/ion-pair network.
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Affiliation(s)
- M I Arnone
- Dipartimento di Chimica Organica e Biologica, Università di Napoli, Federico II, Italy
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9
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Zannini M, Acebron A, De Felice M, Arnone MI, Martin-Pérez J, Santisteban P, Di Lauro R. Mapping and functional role of phosphorylation sites in the thyroid transcription factor-1 (TTF-1). J Biol Chem 1996; 271:2249-54. [PMID: 8567686 DOI: 10.1074/jbc.271.4.2249] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [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: 01/31/2023] Open
Abstract
The phosphorylation of thyroid transcription factor-1 (TTF-1), is homeodomain-containing transcription factor that is required for thyroid-specific expression of the thyroglobulin and thyroperoxidase gene promoters, has been studied. Phosphorylation occurs on a maximum of seven serine residues that are distributed in three tryptic peptides. Mutant derivatives of TTF-1, with alanine sites, have been constructed and used to assess the functional relevance of TTF-1 phosphorylation. The DNA binding activity of TTF-1 appears to be phosphorylation-independent, as indicated also by the performance of TTF-1 purified from an overexpressing Escherichia coli strain. Transcriptional activation by TTF-1 could require phosphorylation only in specific cell types since in a co-transfection assay in heterologous cells both wild-type and mutant proteins show a similar transcriptional activity.
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Affiliation(s)
- M Zannini
- Stazione Zoologica A. Dohrn, Napoli, Italy
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10
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Arnone MI, Zannini M, Di Lauro R. The DNA binding activity and the dimerization ability of the thyroid transcription factor I are redox regulated. J Biol Chem 1995; 270:12048-55. [PMID: 7744853 DOI: 10.1074/jbc.270.20.12048] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [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: 01/26/2023] Open
Abstract
The DNA binding activity of the thyroid transcription factor-1 (TTF-1), a homeodomain-containing protein implicated in the control of thyroid- and lung-specific transcription, is controlled, in vitro, by the redox potential. Oxidation decreases TTF-1 DNA binding activity, which is fully restored upon exposure to reducing agents. The decrease in DNA binding activity is due to the formation of disulfide bond(s), formed between two specific cysteine residues located outside the TTF-1 homeodomain; hence, oxidation does not appear to directly hinder TTF-1/DNA contacts. Disulfide bond formation seems to stabilize preexisting, loosely associated, TTF-1 dimers, which, upon oxidation, proceed in the formation of specific, higher order oligomers.
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Affiliation(s)
- M I Arnone
- Stazione Zoologica A. Dohrn, Villa Comunale, Napoli, Italy
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11
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Affiliation(s)
- R Di Lauro
- Stazione Zoologica Anton Dohrn, Napoli, Italy
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12
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Cubellis MV, Arnone MI, Birolo L, Sannia G, Marino G. Comparative studies on thermophilicity and thermostability of aspartate aminotransferases. Biotechnol Appl Biochem 1993; 18:417-25. [PMID: 8297515] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Aspartate aminotransferase from Sulfolobus solfataricus (AspATSs) is an extremely thermophilic and thermostable enzyme. In order to investigate the structural features which underlie thermophilicity and thermostability, two isoforms of AspATSs differing by a single amino acid residue were compared. The first isoform is the naturally occurring enzyme, whereas the second is a genetically engineered mutant. Thermophilicity, short-term and long-term thermostability of the isoenzymes were independently evaluated and the influence of a cysteine residue on the three properties was assessed.
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Affiliation(s)
- M V Cubellis
- Dipartimento di Chimica Organica e Biologica, Università di Napoli, Italy
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13
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Arnone MI, Birolo L, Cubellis MV, Nitti G, Marino G, Sannia G. Expression of a hyperthermophilic aspartate aminotransferase in Escherichia coli. Biochim Biophys Acta 1992; 1160:206-12. [PMID: 1445947 DOI: 10.1016/0167-4838(92)90009-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The gene for an archaebacterial hyperthermophilic enzyme, aspartate aminotransferase from Sulfolobus solfataricus (AspATSs), was expressed in Escherichia coli and the enzyme purified to homogeneity. A suitable expression vector and host strain were selected and culture conditions were optimized so that 6-7 mg of pure enzyme per litre of culture were obtained repeatedly. The recombinant enzyme and the authentic AspATSs are indistinguishable: in fact, they have the same molecular weight, estimated by means of SDS-PAGE and gel filtration, the same Km values for 2-oxo-glutarate and cysteine sulphinate and the same UV-visible spectra. Moreover, recombinant AspATSs is thermophilic and thermostable just as the enzyme extracted from Sulfolobus solfataricus. The protocol described may be used to produce thermostable arachaebacterial enzymes in mesophilic hosts.
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Affiliation(s)
- M I Arnone
- Dipartimento di Chimica Organica e Biologica, Università di Napoli, Italy
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14
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Arnone MI, Birolo L, Giamberini M, Cubellis MV, Nitti G, Sannia G, Marino G. Limited proteolysis as a probe of conformational changes in aspartate aminotransferase from Sulfolobus solfataricus. Eur J Biochem 1992; 204:1183-9. [PMID: 1551394 DOI: 10.1111/j.1432-1033.1992.tb16745.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The analysis of conformational transitions using limited proteolysis was carried out on a hyperthermophilic aspartate aminotransferase isolated from the archaebacterium Sulfolobus solfataricus, in comparison with pig cytosolic aspartate aminotransferase, a thoroughly studied mesophilic aminotransferase which shares about 15% similarity with the archaebacterial protein. Aspartate aminotransferase from S. solfataricus is cleaved at residue 28 by thermolysin and residues 32 and 33 by trypsin; analogously, pig heart cytosolic aspartate aminotransferase is cleaved at residues 19 and 25 [Iriarte, A., Hubert, E., Kraft, K. & Martinez-Carrion, M. (1984) J. Biol. Chem. 259, 723-728] by trypsin. In the case of aspartate aminotransferase from S. solfataricus, proteolytic cleavages also result in transaminase inactivation thus indicating that both enzymes, although evolutionarily distinct, possess a region involved in catalysis and well exposed to proteases which is similarly positioned in their primary structure. It has been reported that the binding of substrates induces a conformational transition in aspartate aminotransferases and protects the enzymes against proteolysis [Gehring, H. (1985) in Transaminases (Christen, P. & Metzler, D. E., eds) pp. 323-326, John Wiley & Sons, New York]. Aspartate aminotransferase from S. solfataricus is protected against proteolysis by substrates, but only at high temperatures (greater than 60 degrees C). To explain this behaviour, the kinetics of inactivation caused by thermolysin were measured in the temperature range 25-75 degrees C. The Arrhenius plot of the proteolytic kinetic constants measured in the absence of substrates is not rectilinear, while the same plot of the constants measured in the presence of substrates is a straight line. Limited proteolysis experiments suggest that aspartate aminotransferase from S. solfataricus undergoes a conformational transition induced by the binding of substrates. Another conformational transition which depends on temperature and occurs in the absence of substrates could explain the non-linear Arrhenius plot of the proteolytic kinetic constants. The latter conformational transition might also be related to the functioning of the archaebacterial aminotransferase since the Arrhenius plot of kcat is non-linear as well.
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Affiliation(s)
- M I Arnone
- Dipartimento di Chimica Organica e Biologica, Università di Napoli, Italy
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15
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Birolo L, Arnone MI, Cubellis MV, Andreotti G, Nitti G, Marino G, Sannia G. The active site of Sulfolobus solfataricus aspartate aminotransferase. Biochim Biophys Acta 1991; 1080:198-204. [PMID: 1954227 DOI: 10.1016/0167-4838(91)90002-h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Aspartate aminotransferase from the archaebacterium Sulfolobus solfataricus binds pyridoxal 5' phosphate, via an aldimine bond, with Lys-241. This residue has been identified by reducing the enzyme in the pyridoxal form with sodium cyanoboro[3H]hydride and sequencing the specifically labeled peptic peptides. The amino acid sequence centered around the coenzyme binding site is highly conserved between thermophilic aspartate aminotransferases and differs from that found in mesophilic isoenzymes. An alignment of aspartate aminotransferase from Sulfolobus solfataricus with mesophilic isoenzymes, attempted in spite of the low degree of similarity, was confirmed by the correspondence between pyridoxal 5' phosphate binding residues. Using this alignment it was possible to insert the archaebacterial aspartate aminotransferase into a subclass, subclass I, of pyridoxal 5' phosphate binding enzymes comprising mesophilic aspartate aminotransferases, tyrosine aminotransferases and histidinol phosphate aminotransferases. These enzymes share 12 invariant amino acids most of which interact with the coenzyme or with the substrates. Some enzymes of subclass I and in particular aspartate aminotransferase from Sulfolobus solfataricus, lack a positively charged residue, corresponding to Arg-292, which in pig cytosolic aspartate aminotransferase interacts with the distal carboxylate of the substrates (and determines the specificity towards dicarboxylic acids). It was confirmed that aspartate aminotransferase from Sulfolobus solfataricus does not possess any arginine residue exposed to chemical modifications responsible for the binding of omega-carboxylate of the substrates. Furthermore, it has been found that aspartate aminotransferase from Sulfolobus solfataricus is fairly active when alanine is used as substrate and that this activity is not affected by the presence of formate. The KM value of the thermophilic aspartate aminotransferase towards alanine is at least one order of magnitude lower than that of the mesophilic analogue enzymes.
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Affiliation(s)
- L Birolo
- Dipartimento di Chimica Organica e Biologica, Università di Napoli Federico II, Italy
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16
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Cubellis MV, Rozzo C, Nitti G, Arnone MI, Marino G, Sannia G. Cloning and sequencing of the gene coding for aspartate aminotransferase from the thermoacidophilic archaebacterium Sulfolobus solfataricus. Eur J Biochem 1989; 186:375-81. [PMID: 2513189 DOI: 10.1111/j.1432-1033.1989.tb15219.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The gene coding for aspartate aminotransferase (EC 2.6.1.1) has been cloned from the extreme thermoacidophilic archaebacterium Sulfolobus solfataricus strain MT4. Partial sequence data obtained directly from the purified protein and from the two cyanogen-bromide-generated peptides confirm the primary structure of aspartate aminotransferase inferred from the nucleotide sequence of its gene. A comparison of the enzyme with other aminotransferases revealed an interesting similarity with tyrosine aminotransferase from rat liver (EC 2.6.1.5) and allowed some tentative assignments of the residues implied in the catalysis. The aspartate aminotransferase gene-flanking regions were compared to those of other archaebacterial genes already described in the literature with the aim of identifying potential regulatory sites.
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Affiliation(s)
- M V Cubellis
- Dipartimento di Chimica Organica e Biologica, Università di Napoli, Italy
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Marino G, Nitti G, Arnone MI, Sannia G, Gambacorta A, De Rosa M. Purification and characterization of aspartate aminotransferase from the thermoacidophilic archaebacterium Sulfolobus solfataricus. J Biol Chem 1988; 263:12305-9. [PMID: 3137225] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Aspartate aminotransferase from the archaebacterium Sulfolobus solfataricus, a thermoacidophilic organism isolated from an acidic hot spring (optimal growth conditions: 87 degrees C, pH 3.5) was purified to homogeneity. The enzyme is a dimer (Mr subunit = 53,000) showing microheterogeneity when submitted to chromatofocusing and/or isoelectric focusing analysis (two main bands having pI = 6.8 and 6.3 were observed). The N-terminal sequence (22 residues) does not show any homology with any stretch of known sequence of aspartate aminotransferases from animal and bacterial sources. The apoenzyme can be reconstituted with pyridoxamine 5'-phosphate and/or pyridoxal 5'-phosphate, each subunit binding 1 mol of coenzyme. The absorption maxima of the pyridoxamine and pyridoxal form are centered at 325 and 335 nm, respectively; the shape of the pyridoxal form band does not change with pH. The enzyme has an optimum temperature higher than 95 degrees C, and at 100 degrees C shows a half-inactivation time of 2 h. The above properties seem to be unique even for enzymes from extreme thermophiles (Daniel, R. M. (1986) in Protein Structure, Folding, and Design (Oxender, D. L., ed) pp. 291-296, Alan R. Liss, Inc., New York) and lead to the conclusion that aspartate aminotransferase from S. solfataricus is one of the most thermophilic and thermostable enzymes so far known.
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Affiliation(s)
- G Marino
- Dipartimento di Chimica Organica e Biologica, Universita' di Napoli, Italy
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