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Abstract
The ethylene-forming enzyme (EFE), like many other 2-oxoglutarate (2OG)-dependent nonheme iron(II) oxygenases, catalyzes the oxidative decarboxylation of 2OG to succinate and CO2 to generate a highly reactive iron species that hydroxylates a specific alkane C-H bond, in this case targeting l-arginine (Arg) for hydroxylation. However, the prominently observed reactivity of EFE is the transformation of 2OG into ethylene and three molecules of CO2. Crystallographic and biochemical studies have led to several proposed mechanisms for this 2-fold reactivity, but the detailed reaction steps are still obscure. Here, the thermodynamics associated with iron(II), 2OG, and Arg binding to EFE are studied using calorimetry (isothermal titration calorimetry and differential scanning calorimetry) to gain insight into how these binding equilibria organize the active site of EFE, which may have an impact on the O2 activation pathways observed in this system. Calorimetric data show that the addition of iron(II), Arg, and 2OG increases the stability over that of the apoenzyme, and there is distinctive cooperativity between substrate and cofactor binding. The energetics of binding of 2OG to Fe·EFE are consistent with a unique monodentate binding mode, which is different than the prototypical 2OG coordination mode in other 2OG-dependent oxygenases. This difference in the pre-O2 activation equilibria may be important for supporting the alternative ethylene-forming chemistry of EFE.
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Affiliation(s)
- Mingjie Li
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Salette Martinez
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-4320, United States
| | - Robert P. Hausinger
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-4320, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-4320, United States
| | - Joseph P. Emerson
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
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2
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Abstract
1-Aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase are key enzymes in the ethylene biosynthetic pathway in plant tissues, and in vitro assay of their activities is indispensable for analysis, especially, for studying the action mechanism of inhibitors of ethylene biosynthesis. The enzymes can be obtained from plant tissues that are producing ethylene abundantly, such as ripening fruit- and senescing flower tissues, but it is necessary to separate the enzymes from co-extracted ACC by partial purification, making the procedure laborious and time-consuming. Here, we describe the production of the enzymes in Escherichia coli cells from corresponding cDNAs, and the procedures for assay of activities of the enzymes.
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Affiliation(s)
- Shigeru Satoh
- Faculty of Agriculture, Ryukoku University, Otsu, 520-2194, Japan.
| | - Yusuke Kosugi
- Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa, 761-0795, Japan
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3
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Selvi AA, Manonmani HK. Purification and characterization of carbon-phosphorus bond-cleavage enzyme from glyphosate degrading Pseudomonas putida T5. Prep Biochem Biotechnol 2015; 45:380-97. [PMID: 24840030 DOI: 10.1080/10826068.2014.923448] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
An inducible, carbon-phosphorus bond-cleavage enzyme was purified from cells of Pseudomonas putida T5 grown on N-phosphonomethyl glycine. The native enzyme had a molecular mass of approximately 70 kD and upon sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), yielded a homogeneous protein band with an apparent molecular mass of about 70 kD. Activity of purified enzyme was increased by 627-fold compared to the crude extract and showed pH and temperature optima of approximately 7 and 30°C, respectively. The purified enzyme had an apparent Km and Vmax of 3.7 mM and 6.8 mM/min, respectively, for its sole substrate N-phosphonomethyl glycine. The enzyme was inhibited by phenylmethylsulfonyl fluoride (PMSF), indicating the presence of serine at the active site. The enzyme was not inhibited by SDS, suggesting the absence of disulfide linkage in the enzyme. The enzyme was found to be inhibited by most of the metals studied except Mg(2+). Detergents studied also inhibited glyphosate acting as a carbon-phosphorus bond-cleavage enzyme. Thus initial characterization of the purified enzyme suggested that it could be used as a potential candidate for glyphosate bioremediation.
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Affiliation(s)
- A Arul Selvi
- a Fermentation Technology and Bioengineering Department , Central Food Technological Research Institute (CSIR) , Mysore , Karnataka , India
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4
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Munt O, Prüfer D, Schulze Gronover C. A novel C-S lyase from the latex-producing plant Taraxacum brevicorniculatum displays alanine aminotransferase and l-cystine lyase activity. J Plant Physiol 2013; 170:33-40. [PMID: 23073363 DOI: 10.1016/j.jplph.2012.08.018] [Citation(s) in RCA: 2] [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] [Received: 07/10/2012] [Revised: 08/14/2012] [Accepted: 08/16/2012] [Indexed: 06/01/2023]
Abstract
We isolated a novel pyridoxal-5-phosphate-dependent l-cystine lyase from the dandelion Taraxacum brevicorniculatum. Real time qPCR analysis showed that C-S lyase from Taraxacum brevicorniculatum (TbCSL) mRNA is expressed in all plant tissues, although at relatively low levels in the latex and pedicel. The 1251 bp TbCSL cDNA encodes a protein with a calculated molecular mass of 46,127 kDa. It is homologous to tyrosine and alanine aminotransferases (AlaATs) as well as to an Arabidopsis thaliana carbon-sulfur lyase (C-S lyase) (SUR1), which has a role in glucosinolate metabolism. TbCSL displayed in vitrol-cystine lyase and AlaAT activities of 4 and 19nkatmg(-1) protein, respectively. However, we detected no in vitro tyrosine aminotransferase (TyrAT) activity and RNAi knockdown of the enzyme had no effect on phenotype, showing that TbCSL substrates might be channeled into redundant pathways. TbCSL is in vivo localized in the cytosol and functions as a C-S lyase or an aminotransferase in planta, but the purified enzyme converts at least two substrates specifically, and can thus be utilized for further in vitro applications.
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Affiliation(s)
- Oliver Munt
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität Münster, Hindenburgplatz 55, 48143 Münster, Germany
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5
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Choudhury SR, Roy S, Sengupta DN. A Ser/Thr protein kinase phosphorylates MA-ACS1 (Musa acuminata 1-aminocyclopropane-1-carboxylic acid synthase 1) during banana fruit ripening. Planta 2012; 236:491-511. [PMID: 22419220 DOI: 10.1007/s00425-012-1627-9] [Citation(s) in RCA: 13] [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] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 02/24/2012] [Indexed: 05/09/2023]
Abstract
1-Aminocyclopropane-1-carboxylic acid synthase (ACS) catalyzes the rate-limiting step in ethylene biosynthesis during ripening. ACS isozymes are regulated both transcriptionally and post-translationally. However, in banana, an important climacteric fruit, little is known about post-translational regulation of ACS. Here, we report the post-translational modification of MA-ACS1 (Musa acuminata ACS1), a ripening inducible isozyme in the ACS family, which plays a key role in ethylene biosynthesis during banana fruit ripening. Immunoprecipitation analyses of phospholabeled protein extracts from banana fruit using affinity-purified anti-MA-ACS1 antibody have revealed phosphorylation of MA-ACS1, particularly in ripe fruit tissue. We have identified the induction of a 41-kDa protein kinase activity in pulp at the onset of ripening. The 41-kDa protein kinase has been identified as a putative protein kinase by MALDI-TOF/MS analysis. Biochemical analyses using partially purified protein kinase fraction from banana fruit have identified the protein kinase as a Ser/Thr family of protein kinase and its possible involvement in MA-ACS1 phosphorylation during ripening. In vitro phosphorylation analyses using synthetic peptides and site-directed mutagenized recombinant MA-ACS1 have revealed that serine 476 and 479 residues at the C-terminal region of MA-ACS1 are phosphorylated. Overall, this study provides important novel evidence for in vivo phosphorylation of MA-ACS1 at the molecular level as a possible mechanism of post-translational regulation of this key regulatory protein in ethylene signaling pathway in banana fruit during ripening.
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Affiliation(s)
- Swarup Roy Choudhury
- Division of Plant Biology, Bose Institute, 93/1, Acharya Prafulla Chandra Road, Kolkata, 700 009, West Bengal, India.
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6
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Lai KW, Yau CP, Tse YC, Jiang L, Yip WK. Heterologous expression analyses of rice OsCAS in Arabidopsis and in yeast provide evidence for its roles in cyanide detoxification rather than in cysteine synthesis in vivo. J Exp Bot 2009; 60:993-1008. [PMID: 19181864 PMCID: PMC2652057 DOI: 10.1093/jxb/ern343] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
While most dicot plants produce little ethylene in their vegetative stage, many monocots such as rice liberate a relatively large amount of ethylene with cyanide as a co-product in their seedling stage when etiolated. One of the known functions of beta-cyanoalanine synthase (CAS) is to detoxify the co-product cyanide during ethylene biosynthesis in higher plants. Based on a tryptic peptide sequence obtained from a partially purified CAS activity protein preparation in etiolated rice seedlings, the full-length putative rice CAS-encoding cDNA sequence (OsCAS), which is homologous to those O-acetylserine sulphydrylase (OASS) genes, was cloned. Unlike most of the CAS genes reported from dicots, the transcription of OsCAS is promoted by auxins but suppressed by ethylene. To address the function and the subcellular localization of this gene product in planta, a binary vector construct consisting of this gene appended with a yellow fluorescent protein-encoding sequence was employed to transform Arabidopsis. Specific activities on CAS and OASS of the purified recombinant protein from transgenic Arabidopsis were 181.04 micromol H(2)S mg(-1) protein min(-1) and 0.92 micromol Cys mg(-1) protein min(-1), respectively, indicating that OsCAS favours CAS activity. The subcellular localization of OsCAS was found mostly in the mitochondria by immunogold electron-microscopy. Chemical cross-linking and in-gel assay on a heterodimer composed of functional and non-functional mutants in a yeast expression system on OsCAS suggested that OsCAS functions as a homodimer, similar to that of OASS. Despite the structural similarity of OsCAS with OASS, it has also been confirmed that OsCAS could not interact with serine-acetyltransferase, indicating that OsCAS mainly functions in cyanide detoxification.
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Affiliation(s)
- Kwok Wai Lai
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Chi Ping Yau
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Yu Chung Tse
- Department of Biology and Molecular Biotechnology Program, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Liwen Jiang
- Department of Biology and Molecular Biotechnology Program, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, China
| | - Wing Kin Yip
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, China
- To whom correspondence should be addressed. E-mail:
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Hartshorne RS, Kern M, Meyer B, Clarke TA, Karas M, Richardson DJ, Simon J. A dedicated haem lyase is required for the maturation of a novel bacterial cytochrome c with unconventional covalent haem binding. Mol Microbiol 2007; 64:1049-60. [PMID: 17501927 DOI: 10.1111/j.1365-2958.2007.05712.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [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: 11/29/2022]
Abstract
In bacterial c-type cytochromes, the haem cofactor is covalently attached via two cysteine residues organized in a haem c-binding motif. Here, a novel octa-haem c protein, MccA, is described that contains only seven conventional haem c-binding motifs (CXXCH), in addition to several single cysteine residues and a conserved CH signature. Mass spectrometric analysis of purified MccA from Wolinella succinogenes suggests that two of the single cysteine residues are actually part of an unprecedented CX15CH sequence involved in haem c binding. Spectroscopic characterization of MccA identified an unusual high-potential haem c with a red-shifted absorption maximum, not unlike that of certain eukaryotic cytochromes c that exceptionally bind haem via only one thioether bridge. A haem lyase gene was found to be specifically required for the maturation of MccA in W. succinogenes. Equivalent haem lyase-encoding genes belonging to either the bacterial cytochrome c biogenesis system I or II are present in the vicinity of every known mccA gene suggesting a dedicated cytochrome c maturation pathway. The results necessitate reconsideration of computer-based prediction of putative haem c-binding motifs in bacterial proteomes.
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Affiliation(s)
- Robert S Hartshorne
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
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8
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Ogunlabi OO, Agboola FK. A soluble beta-cyanoalanine synthase from the gut of the variegated grasshopper Zonocerus variegatus (L.). Insect Biochem Mol Biol 2007; 37:72-9. [PMID: 17175447 DOI: 10.1016/j.ibmb.2006.10.003] [Citation(s) in RCA: 8] [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] [Received: 08/14/2006] [Revised: 10/15/2006] [Accepted: 10/23/2006] [Indexed: 05/13/2023]
Abstract
Beta-cyanoalanine synthase (beta-cyano-l-alanine synthase; l-cysteine: hydrogen sulphide lyase (adding hydrogen cyanide (HCN)); EC 4. 4.1.9) was purified from the cytosolic fraction of the gut of grasshopper Zonocerus variegatus (L.) by ion-exchange chromatography on DEAE-Cellulose and gel filtration on Sephadex G-100 columns. The crude enzyme had a specific activity of 2.16nmol H2S/min/mg. A purified enzyme with a specific activity, which was seventeen times higher than that of the crude extract, was obtained. A molecular weight of about 55.23+/-1.00Kd was estimated from its elution volume on Sephadex G-100. The fraction when subjected to sodium dodecyl sulphate-polyacrylamide elel electrophoresis revealed the presence of a protein band with Mr of 23.25+/-0.25Kd. The enzyme exhibited Michaelis-Menten kinetics having Km of 0.38mM for l-cysteine and Km of 6.25mM for cyanide. The optimum temperature and pH for activity were determined to be at 30 degrees C and pH 9.0, respectively. This enzyme might be responsible for the ability to detoxify cyanide in this insect pest and hence its tolerance of the cyanogenic cassava plant. Biophysical, biochemical and kinetic properties of this enzyme, which will reveal how this ability can possibly be compromised by enzyme inhibition, may lead, in the long term, to the potential use of this enzyme as drug target for pest control.
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Cescutti P, Scussolin S, Herasimenka Y, Impallomeni G, Bicego M, Rizzo R. First report of a lyase for cepacian, the polysaccharide produced by Burkholderia cepacia complex bacteria. Biochem Biophys Res Commun 2006; 339:821-6. [PMID: 16325774 DOI: 10.1016/j.bbrc.2005.11.104] [Citation(s) in RCA: 9] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Accepted: 11/16/2005] [Indexed: 11/27/2022]
Abstract
Bacteria belonging to the Burkholderia cepacia complex (Bcc) are interesting for their involvement in pulmonary infections in patients affected by cystic fibrosis (CF) or chronic granulomatous disease. Many Bcc strains isolated from CF patients produce high amounts of exopolysaccharides (EPS). Although different strains sometimes biosynthesise different EPS, the majority of Bcc bacteria produce only one type of polysaccharide, which is called cepacian. The polymer has a unique heptasaccharidic repeating unit, containing three side chains, and up to three O-acetyl substituents.. We here report for the first time the isolation and characterisation of a lyase active towards cepacian produced by a Bacillus sp., which was isolated in our laboratory. The enzyme molecular mass, evaluated by size-exclusion chromatography, is 32,700+/-1500Da. The enzyme catalyses a beta-elimination reaction of the disaccharide side chain beta-d-Galp-(1-->2)-alpha-d-Rhap-(1--> from the C-4 of the glucuronic acid residue present in the polymer backbone. Although active on both native and de-acetylated cepacian, the enzyme showed higher activity on the latter polymer.
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Affiliation(s)
- Paola Cescutti
- Dipartimento di Biochimica Biofisica e Chimica delle Macromolecole, Università di Trieste, via L. Giorgieri 1, I-34127 Trieste, Italy.
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10
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Witschel M, Egli T. Purification and characterization of a lyase from the EDTA-degrading bacterial strain DSM 9103 that catalyzes the splitting of [S,S]-ethylenediaminedisuccinate, a structural isomer of EDTA. Biodegradation 2005; 8:419-28. [PMID: 15765587 DOI: 10.1023/a:1008267931018] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [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: 11/12/2022]
Abstract
The bacterial strain DSM 9103, able to utilize EDTA as a sole source of carbon, nitrogen, and energy, is also capable to grow with [S,S]-ethylenediaminedisuccinate ([S,S]-EDDS), a structural isomer of EDTA. In cell-free extracts of [S,S]-EDDS-grown bacteria, [S,S]-EDDS degradation was observed in the absence of any cofactors. An enzyme was purified 41-fold that catalyzed the non-hydrolytic splitting of [S,S]-EDDS leading to the formation of fumarate and N-(2-aminoethyl) aspartic acid. These data strongly suggest that the enzyme belongs to the group of carbon-nitrogen lyases. The splitting reaction was reversible, and an equilibrium constant of approximately 43.0 10(-1) M was determined. Out of the three stereo-isomers of EDDS, [S,S]- and [R,S]-EDDS were accepted as substrates by the lyase, whereas [R,R]-EDDS remained unchanged in assays with both cell-free extracts and pure enzyme. The enzyme catalyzed the transformation of free [S,S]-EDDS and of [S,S]-EDDS-metal complexes with stability constant lower than 10, namely of MgEDDS, CaEDDS, BaEDDS and to a small extent also of MnEDDS; FeIIIEDDS, NiEDDS, CuEDDS, CoEDDS and ZnEDDS were not transformed.
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Affiliation(s)
- M Witschel
- Swiss Federal Institute for Environmental Science and Technology (EAWAG) and Swiss Federal Institute of Technology (ETH), CH-8600 Dübendorf, Switzerland
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11
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Matarasso N, Schuster S, Avni A. A novel plant cysteine protease has a dual function as a regulator of 1-aminocyclopropane-1-carboxylic Acid synthase gene expression. Plant Cell 2005; 17:1205-16. [PMID: 15749766 PMCID: PMC1087997 DOI: 10.1105/tpc.105.030775] [Citation(s) in RCA: 43] [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] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Accepted: 02/16/2005] [Indexed: 05/19/2023]
Abstract
The hormone ethylene influences plant growth, development, and some defense responses. The fungal elicitor Ethylene-Inducing Xylanase (EIX) elicits ethylene biosynthesis in tomato (Lycopersicon esculentum) and tobacco (Nicotiana tabacum) leaves by induction of 1-aminocyclopropane-1-caboxylic acid synthase (Acs) gene expression. A minimal promoter element in the LeAcs2 gene required for EIX responsiveness was defined by deletion analysis in transgenic tomato plants. The sequence between -715 and -675 of the tomato Acs2 gene was found to be essential for induction by EIX. A Cys protease (LeCp) was isolated that specifically binds to this cis element in vitro. Ectopic expression of LeCp in tomato leaves induced the expression of Acs2. Moreover, chromatin immunoprecipitation showed that LeCp binds in vivo to the Acs promoter. We propose a mechanism for the dual function of the LeCp protein. The protease acts enzymatically in the cytoplasm. Then, upon signaling, a small ubiquitin-related modifier protein binds to it, enabling entrance into the nucleus, where it acts as a transcription factor. Thus, LeCp can be considered a dual-function protein, having enzymatic activity and, upon elicitor signaling, exhibiting transcriptional factor activity that induces LeAcs2 expression.
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MESH Headings
- Active Transport, Cell Nucleus/physiology
- Cysteine Endopeptidases/genetics
- Cysteine Endopeptidases/isolation & purification
- Cysteine Endopeptidases/metabolism
- DNA, Complementary/analysis
- DNA, Complementary/genetics
- Gene Expression Regulation, Enzymologic/physiology
- Gene Expression Regulation, Plant/physiology
- Lyases/genetics
- Lyases/isolation & purification
- Lyases/metabolism
- Solanum lycopersicum/enzymology
- Solanum lycopersicum/genetics
- Molecular Sequence Data
- Plant Proteins/genetics
- Plant Proteins/isolation & purification
- Plant Proteins/metabolism
- Plants, Genetically Modified/enzymology
- Plants, Genetically Modified/genetics
- Promoter Regions, Genetic/genetics
- Protein Binding/physiology
- Response Elements/genetics
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Transcription Factors/genetics
- Transcription Factors/isolation & purification
- Transcription Factors/metabolism
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Affiliation(s)
- Noa Matarasso
- Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Teranishi M, Iwamatsu Y, Hidema J, Kumagai T. Ultraviolet-B sensitivities in Japanese lowland rice cultivars: cyclobutane pyrimidine dimer photolyase activity and gene mutation. Plant Cell Physiol 2004; 45:1848-1856. [PMID: 15653803 DOI: 10.1093/pcp/pch215] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
There is a cultivar difference in the response to ultraviolet-B (UVB: 280-320 nm) in rice (Oryza sativa L.). Among Japanese lowland rice cultivars, Sasanishiki, a leading Japanese rice cultivar, is resistant to the damaging effects of UVB while Norin 1, a close relative, is less resistant. We found previously that Norin 1 was deficient in cyclobutane pyrimidine dimer (CPD) photorepair ability and suggested that the UVB sensitivity in rice depends largely on CPD photorepair ability. In order to verify that suggestion, we examined the correlation between UVB sensitivity and CPD photolyase activity in 17 rice cultivars of progenitors and relatives in breeding of UV-resistant Sasanishiki and UV-sensitive Norin 1. The amino acid at position 126 of the deduced amino acid sequence of CPD photolyase in cultivars including such as Norin 1 was found to be arginine, the CPD photolyase activities of which were lower. The amino acid at that position in cultivars including such as Sasanishiki was glutamine. Furthermore, cultivars more resistant to UVB were found to exhibit higher photolyase activities than less resistant cultivars. These results emphasize that single amino acid alteration from glutamine to arginine leads to a deficit of CPD photolyase activity and that CPD photolyase activity is one of the main factors determining UVB sensitivity in rice.
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Affiliation(s)
- Mika Teranishi
- Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577 Japan
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13
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Stepnaia OA, Begunova EA, Tsfasman IM, Tul'skaia EM, Streshinskaia GM, Naumova IB, Kulaev IS. [Mechanism of action of the extracellular bacteriolytic enzymes of Lysobacter sp. on gram-positive bacteria: role of the cell wall anionic polymers of the target bacteria]. Mikrobiologiia 2004; 73:479-85. [PMID: 15521173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The study of the extracellular bacteriolytic enzymes of Lysobacter sp. showed that they can efficiently hydrolyze the peptidoglycan of gram-positive bacteria provided that there is an electrostatic interaction of these enzymes with the cell wall anionic polymers, teichoic and teichuronic acids in particular. The hydrolytic action of bacteriolytic enzymes on the cell wall largely depends on the negative charge of teichoic and teichuronic acids, rather than on their chemical composition.
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Alekseeva SA, Bakunina IY, Nedashkovskaya OI, Isakov VV, Mikhailov VV, Zvyagintseva TN. Intracellular alginolytic enzymes of the marine bacterium Pseudoalteromonas citrea KMM 3297. Biochemistry (Mosc) 2004; 69:262-9. [PMID: 15061691 DOI: 10.1023/b:biry.0000022055.33763.62] [Citation(s) in RCA: 8] [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: 11/12/2022]
Abstract
The marine bacterium Pseudoalteromonas citrea KMM 3297 is an associate of the holothurian Apostichopus japonicus. When grown in a medium containing glucose, the strain produces two intracellular alginolytic enzymes, AlI and AlII. Fucoidan from the brown alga Fucus evanescens induces synthesis of one more alginolytic enzyme, AlIII. These enzymes were separated using anion-exchange chromatography. The alginate lyase AlI completely retains its activity at 35 degrees C, AlII and AlIII being stable at 45 degrees C. The alginate lyases exhibit maximal activities in the range of pH 7-8. The molecular weights of AlI, AlII, and AlIII determined by gel filtration are 25, 79, and 61 kD, respectively. All the investigated enzymes are endo-type alginate lyases. They catalyze degradation of polyguluronate (poly-G) and polymannuronate (poly-M) yielding oligosaccharides of the polymerization degree of 5 > or = n > or = 3 with the unsaturated bond between the C4 and C5 atoms of the non-reducing terminus. A mixture of these three enzymes exhibits synergism while acting on the polymeric substrate. The Km values of the alginate lyase AlI for poly-G and poly-M are 24 and 34 micro g/ml, respectively. Alginate lyase AlIII exhibits less affinity to poly-M (Km = 130.0 microg/ml) than to poly-G (Km = 40.0 microg/ml). NaCl (0.2 M), MgCl2 and MgSO4 (0.01 M) activate all three enzymes more than twofold. The presence of several alginolytic enzymes of different specificity provides efficient destruction of alginic acids of brown algae by the strain P. citrea KMM 3297.
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Affiliation(s)
- S A Alekseeva
- Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok 690022, Russia
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15
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Tsuchisaka A, Theologis A. Heterodimeric interactions among the 1-amino-cyclopropane-1-carboxylate synthase polypeptides encoded by the Arabidopsis gene family. Proc Natl Acad Sci U S A 2004; 101:2275-80. [PMID: 14983000 PMCID: PMC356941 DOI: 10.1073/pnas.0308515101] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Indexed: 11/18/2022] Open
Abstract
The pyridoxal phosphate-dependent enzyme, 1-aminocyclopropane-1-carboxylate synthase (ACS; EC 4.4.1.14), catalyzes the rate-limiting step in the ethylene biosynthetic pathway in plants. The Arabidopsis genome encodes nine ACS polypeptides that form eight functional (ACS2, ACS4-9, ACS11) and one nonfunctional (ACS1) homodimers. Because the enzyme is a homodimer with shared active sites, the question arises whether the various polypeptides can form functional heterodimers. Intermolecular complementation experiments in Escherichia coli by coexpressing the K278A and Y92A mutants of different polypeptides show that all of them have the capacity to heterodimerize. However, functional heterodimers are formed only among gene family members that belong to one or the other of the two phylogenetic branches. ACS7 is an exception to this rule, which forms functional heterodimers with some members of both branches when it provides the wt K278 residue. ACS1, the nonfunctional polypeptide as a homodimer, can also form functional heterodimers with members of its phylogenetic branch when its partners provide the wt K278 residue. The ACS gene family products can potentially form 45 homo- and heterodimers of which 25 are functional. Bimolecular fluorescence complementation and biochemical coaffinity purification assays show that the inactivity of certain heterodimers is not due to the absence of heterodimerization but rather to structural restraint(s) that prevents the shared active sites from being functional. We propose that functional heterodimerization enhances the isozyme diversity of the ACS gene family and provides physiological versatility by being able to operate in a broad gradient of S-adenosylmethionine concentration in various cells/tissues during plant growth and development. Nonfunctional heterodimerization may also play a regulatory role during the plant life cycle.
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Affiliation(s)
- Ruth A Schmitz
- Institute for Micorbiology and Genetics, University of Göttingen, Germany
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Yamagami T, Tsuchisaka A, Yamada K, Haddon WF, Harden LA, Theologis A. Biochemical diversity among the 1-amino-cyclopropane-1-carboxylate synthase isozymes encoded by the Arabidopsis gene family. J Biol Chem 2003; 278:49102-12. [PMID: 12968022 DOI: 10.1074/jbc.m308297200] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.3] [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: 11/06/2022] Open
Abstract
1-Amino-cyclopropane-1-carboxylate synthase (ACS, EC 4.4.1.14) is the key enzyme in the ethylene biosynthetic pathway in plants. The completion of the Arabidopsis genome sequence revealed the presence of twelve putative ACS genes, ACS1-12, dispersed among five chromosomes. ACS1-5 have been previously characterized. However, ACS1 is enzymatically inactive whereas ACS3 is a pseudogene. Complementation analysis with the Escherichia coli aminotransferase mutant DL39 shows that ACS10 and 12 encode aminotransferases. The remaining eight genes are authentic ACS genes and together with ACS1 constitute the Arabidopsis ACS gene family. All genes, except ACS3, are transcriptionally active and differentially expressed during Arabidopsis growth and development. IAA induces all ACS genes, except ACS7 and ACS9; CHX enhances the expression of all functional ACS genes. The ACS genes were expressed in E. coli, purified to homogeneity by affinity chromatography, and biochemically characterized. The quality of the recombinant proteins was verified by N-terminal amino acid sequence and MALDI-TOF mass spectrometry. The analysis shows that all ACS isozymes function as dimers and have an optimum pH, ranging between 7.3 and 8.2. Their Km values for AdoMet range from 8.3 to 45 microm, whereas their kcat values vary from 0.19 to 4.82 s-1 per monomer. Their Ki values for AVG and sinefungin vary from 0.019 to 0.80 microm and 0.15 to 12 microm, respectively. The results indicate that the Arabidopsis ACS isozymes are biochemically distinct. It is proposed that biochemically diverse ACS isozymes function in unique cellular environments for the biosynthesis of C2H4, permitting the signaling molecule to exert its unique effects in a tissue- or cell-specific fashion.
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Affiliation(s)
- Takeshi Yamagami
- Plant Gene Expression Center, United States Department of Agriculture, Albany, California 94710, USA
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18
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Tantaleán JC, Araya MA, Saavedra CP, Fuentes DE, Pérez JM, Calderón IL, Youderian P, Vásquez CC. The Geobacillus stearothermophilus V iscS gene, encoding cysteine desulfurase, confers resistance to potassium tellurite in Escherichia coli K-12. J Bacteriol 2003; 185:5831-7. [PMID: 13129955 PMCID: PMC193957 DOI: 10.1128/jb.185.19.5831-5837.2003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [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: 12/22/2022] Open
Abstract
Many eubacteria are resistant to the toxic oxidizing agent potassium tellurite, and tellurite resistance involves diverse biochemical mechanisms. Expression of the iscS gene from Geobacillus stearothermophilus V, which is naturally resistant to tellurite, confers tellurite resistance in Escherichia coli K-12, which is naturally sensitive to tellurite. The G. stearothermophilus iscS gene encodes a cysteine desulfurase. A site-directed mutation in iscS that prevents binding of its pyridoxal phosphate cofactor abolishes both enzyme activity and its ability to confer tellurite resistance in E. coli. Expression of the G. stearothermophilus iscS gene confers tellurite resistance in tellurite-hypersensitive E. coli iscS and sodA sodB mutants (deficient in superoxide dismutase) and complements the auxotrophic requirement of an E. coli iscS mutant for thiamine but not for nicotinic acid. These and other results support the hypothesis that the reduction of tellurite generates superoxide anions and that the primary targets of superoxide damage in E. coli are enzymes with iron-sulfur clusters.
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Affiliation(s)
- Juan C Tantaleán
- Laboratorio de Microbiología Molecular, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
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19
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Abstract
Nuclear genes control plastid differentiation in response to developmental signals, environmental signals, and retrograde signals from plastids themselves. In return, plastids emit signals that are essential for proper expression of many nuclear photosynthetic genes. Accumulation of magnesium-protoporphyrin IX (Mg-Proto), an intermediate in chlorophyll biosynthesis, is a plastid signal that represses nuclear transcription through a signaling pathway that, in Arabidopsis, requires the GUN4 gene. GUN4 binds the product and substrate of Mg- chelatase, an enzyme that produces Mg-Proto, and activates Mg-chelatase. Thus, GUN4 participates in plastid-to-nucleus signaling by regulating Mg-Proto synthesis or trafficking.
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Affiliation(s)
- Robert M Larkin
- Howard Hughes Medical Institute, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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20
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Abstract
Nuclear genes control plastid differentiation in response to developmental signals, environmental signals, and retrograde signals from plastids themselves. In return, plastids emit signals that are essential for proper expression of many nuclear photosynthetic genes. Accumulation of magnesium-protoporphyrin IX (Mg-Proto), an intermediate in chlorophyll biosynthesis, is a plastid signal that represses nuclear transcription through a signaling pathway that, in Arabidopsis, requires the GUN4 gene. GUN4 binds the product and substrate of Mg- chelatase, an enzyme that produces Mg-Proto, and activates Mg-chelatase. Thus, GUN4 participates in plastid-to-nucleus signaling by regulating Mg-Proto synthesis or trafficking.
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Affiliation(s)
- Robert M Larkin
- Howard Hughes Medical Institute, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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Zhao KH, Wu D, Wang L, Zhou M, Storf M, Bubenzer C, Strohmann B, Scheer H. Characterization of phycoviolobilin phycoerythrocyanin-alpha 84-cystein-lyase-(isomerizing) from Mastigocladus laminosus. Eur J Biochem 2002; 269:4542-50. [PMID: 12230566 DOI: 10.1046/j.1432-1033.2002.03148.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cofactor requirements and enzyme kinetics have been studied of the novel, dual-action enzyme, the isomerizing phycoviolobilin phycoerythrocyanin-alpha84-cystein-lyase(PVB-PEC-lyase) from Mastigocladus laminosus, which catalyses both the covalent attachment of phycocyanobilin to PecA, the apo-alpha-subunit of phycoerythrocyanin, and its isomerization to phycoviolobilin. Thiols and the divalent metals, Mg2+ or Mn2+, were required, and the reaction was aided by the detergent, Triton X-100. Phosphate buffer inhibits precipitation of the proteins present in the reconstitution mixture, but at the same time binds the required metal. Kinetic constants were obtained for both substrates, the chromophore (Km = 12-16 micro m, depending on [PecA], kcat approximately 1.2 x 10-4.s-1) and the apoprotein (Km = 2.4 micro m at 14 micro m PCB, kcat = 0.8 x 10-4.s-1). The kinetic analysis indicated that the reconstitution reaction proceeds by a sequential mechanism. By a combination of untagged and His-tagged subunits, evidence was obtained for a complex formation between PecE and PecF (subunits of PVB-PEC-lyase), and by experiments with single subunits for the prevalent function of PecE in binding and PecF in isomerizing the chromophore.
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Affiliation(s)
- Kai-Hong Zhao
- College of Life Science and Technology Huazhong University of Science and Technology, Wuhan, Hubei, China.
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22
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Affiliation(s)
- Hisaaki Mihara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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23
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Aubel D, Germond JE, Gilbert C, Atlan D. Isolation of the patC gene encoding the cystathionine beta-lyase of Lactobacillus delbrueckii subsp. bulgaricus and molecular analysis of inter-strain variability in enzyme biosynthesis. Microbiology (Reading) 2002; 148:2029-2036. [PMID: 12101291 DOI: 10.1099/00221287-148-7-2029] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The patC gene encoding the cystathionine beta-lyase (CBL) of Lactobacillus delbrueckii subsp. bulgaricus NCDO 1489 was cloned and expressed in Escherichia coli. Overexpression of CBL complemented the methionine auxotrophy of an E. coli metC mutant, demonstrating in vivo that this enzyme functions as a CBL. However, PatC is distinguishable from the MetC CBLs by a low identity in amino acid sequence, a sensitivity to iodoacetic acid, greater thermostability and a lower substrate affinity. Homologues of patC were detected in the 13 Lb. delbrueckii strains studied, but only seven of them showed CBL activity. In constrast to CBL(+) strains, all CBL-deficient strains analysed were auxotrophic for methionine. This supports the hypothesis that CBLs from lactobacilli are probably involved in methionine biosynthesis. Moreover, the results of this study suggest that post-transcriptional mechanisms account for the differences in CBL activities observed between strains of Lb. delbrueckii.
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Affiliation(s)
- Dominique Aubel
- Unité de Microbiologie et Génétique, UMR 5122, Université Claude Bernard-Lyon 1, bât. Lwoff, 10 rue Dubois, F-69622 Villeurbanne Cedex, France1
| | | | - Christophe Gilbert
- Unité de Microbiologie et Génétique, UMR 5122, Université Claude Bernard-Lyon 1, bât. Lwoff, 10 rue Dubois, F-69622 Villeurbanne Cedex, France1
| | - Danièle Atlan
- Unité de Microbiologie et Génétique, UMR 5122, Université Claude Bernard-Lyon 1, bât. Lwoff, 10 rue Dubois, F-69622 Villeurbanne Cedex, France1
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Tamegai H, Nango E, Koike-Takeshita A, Kudo F, Kakinuma K. Significance of the 20-kDa subunit of heterodimeric 2-deoxy-scyllo-inosose synthase for the biosynthesis of butirosin antibiotics in Bacillus circulans. Biosci Biotechnol Biochem 2002; 66:1538-45. [PMID: 12224638 DOI: 10.1271/bbb.66.1538] [Citation(s) in RCA: 8] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A gene (btrC2) encoding the 20-kDa subunit of 2-deoxy-scyllo-inosose (DOI) synthase, a key enzyme in the biosynthesis of 2-deoxystreptamine, was identified from the butirosin-producer Bacillus circulans by reverse genetics. The deduced amino acid sequence of BtrC2 closely resembled that of YaaE of B. subtilis, but the function of the latter has not been known to date. Instead, BtrC2 appeared to show sequence similarity to a certain extent with HisH of B. subtilis, an amidotransferase subunit of imidazole glycerol phosphate synthase. Disruption of btrC2 reduced the growth rate compared with the wild type, and simultaneously antibiotic producing activity was lost. Addition of NH4Cl to the medium complemented only the growth rate of the disruptant, and both the growth rate and antibiotic production were restored by addition of yeast extract. In addition, a heterologous co-expression system of btrC2 with btrC was constructed in Escherichia coli. The simultaneously over-expressed BtrC2 and BtrC constituted a heterodimer, the biochemical features of which resembled those of DOI synthase from B. circulans more than those of the recombinant homodimeric BtrC. Despite the similarity of BtrC2 to HisH the heterodimer showed neither aminotransfer nor amidotransfer activity for 2-deoxy-scyllo-inosose as a substrate. All the observations suggest that BtrC2 is involved not only in the secondary metabolism, but also in the primary metabolism in B. circulans. The function of BtrC2 in the butirosin biosynthesis appears to be indirect, and may be involved in stabilization of DOI synthase and in regulation of its enzyme activity.
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Abstract
The present study describes the isolation of a protein from Escherichia coli possessing kynurenine aminotransferase (KAT) activity and its identification as aspartate aminotransferase (AspAT). KAT catalyses the transamination of kynurenine and 3-hydroxykynurenine to kynurenic acid and xanthurenic acid respectively, and the enzyme activity can be easily detected in E. coli cells. Separation of the E. coli protein possessing KAT activity through various chromatographic steps led to the isolation of the enzyme. N-terminal sequencing of the purified protein determined its first 10 N-terminal amino acid residues, which were identical with those of the E. coli AspAT. Recombinant AspAT (R-AspAT), homologously expressed in an E. coli/pET22b expression system, was capable of catalysing the transamination of both l-kynurenine (K(m)=3 mM; V(max)=7.9 micromol.min(-1).mg(-1)) and 3-hydroxy-dl-kynurenine (K(m)=3.7 mM; V(max)=1.25 micromol.min(-1).mg(-1)) in the presence of pyruvate as an amino acceptor, and exhibited its maximum activity at temperatures between 50-60 degrees C and at a pH of approx. 7.0. Like mammalian KATs, R-AspAT also displayed high glutamine transaminase K activity when l-phenylalanine was used as an amino donor (K(m)=8 mM; V(max)=20.6 micromol.min(-1).mg(-1)). The exact match of the first ten N-terminal amino acid residues of the KAT-active protein with that of AspAT, in conjunction with the high KAT activity of R-AspAT, provides convincing evidence that the identity of the E. coli protein is AspAT.
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Affiliation(s)
- Q Han
- Department of Pathobiology, University of Illinois at Champaign-Urbana, 2001 S. Lincoln Avenue, Urbana, IL 61802, U.S.A
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Abstract
To investigate how cell type proportions are regulated during Dictyostelium development, we have attempted to find out which cell type produces DIF-1, a diffusible signal molecule inducing the differentiation of prestalk-O cells. DIF-1 is a chlorinated alkyl phenone that is synthesized from a C12 polyketide precursor by chlorination and methylation, with the final step catalysed by the dmtA methyltransferase. All our evidence points to the prespore cells as the major source of DIF-1. (1) dmtA mRNA and enzyme activity are greatly enriched in prespore compared with prestalk cells. The chlorinating activity is also somewhat prespore-enriched. (2) Expression of dmtA is induced by cyclic-AMP and this induction is inhibited by DIF-1. This regulatory behaviour is characteristic of prespore products. (3) Short-term labelling experiments, using the polyketide precursor, show that purified prespore cells produce DIF-1 at more than 20 times the rate of prestalk cells. (4) Although DIF-1 has little effect on its own synthesis in short-term labelling experiments, in long-term experiments, using 36Cl– as label, it is strongly inhibitory (IC50 about 5 nM), presumably because it represses expression of dmtA; this is again consistent with DIF-1 production by prespore cells. Inhibition takes about 1 hour to become effective.
We propose that prespore cells cross-induce the differentiation of prestalk-O cells by making DIF-1, and that this is one of the regulatory loops that sets the proportion of prespore-to-prestalk cells in the aggregate.
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Affiliation(s)
- R R Kay
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
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Maruyama A, Saito K, Ishizawa K. Beta-cyanoalanine synthase and cysteine synthase from potato: molecular cloning, biochemical characterization, and spatial and hormonal regulation. Plant Mol Biol 2001; 46:749-760. [PMID: 11575729 DOI: 10.1023/a:1011629703784] [Citation(s) in RCA: 25] [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] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Beta-cyanoalanine synthase (CAS, L-3-cyanoalanine synthase; EC 4.4.1.9) is the most important enzyme in cyanide metabolism. In addition to CAS, cysteine synthase (CS, EC 4.2.99.8) possesses CAS activity. To explore the physiological significance of cyanide metabolism, we isolated the cDNA clones corresponding to purified CAS (designated PCAS-1 and PCAS-2) and CS (designated PCS-1 and PCS-2) from potato using the information of these amino acid sequences. The recombinant proteins of PCS-1, PCS-2 and PCAS-1 catalyzed both CAS and CS reactions, although the ratios between CAS and CS activity were remarkably different. PCAS-1 preferred the substrates for the CAS reaction to the substrates for the CS reaction. From the kinetic characters and homology of amino acid sequences with known CS-like proteins, PCS-1, PCS-2 and PCAS-1 were identified as cytosolic CS, plastidic CS and mitochondrial CAS, respectively. The highest level of CAS activity, CAS protein and its mRNA were detected in potato buds. Stimulation of CAS activity and protein accumulation by ethylene without the concomitant increase of its mRNA suggested that ethylene induces CAS protein accumulation at the post-transcriptional level.
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Affiliation(s)
- A Maruyama
- Department of Molecular Biology and Biotechnology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan
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Kato Y, Asano Y. Occurrence of a novel lyase catalyzing beta-elimination reaction toward threo-3-chloro-L-aspartate in Pseudomonas putida TPU 7151. Biosci Biotechnol Biochem 2001; 65:435-7. [PMID: 11302183 DOI: 10.1271/bbb.65.435] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A bacterium, Pseudomonas putida TPU 7151, which degrades threo-3-chloro-L-aspartate, was isolated from soil and the enzyme responsible for the degradation of the amino acid was partially purified from the cell-free extract of the strain. The enzyme, which required PLP for its reaction, catalyzed a stoichiometric beta-elimination reaction of threo-3-chloro-L-aspartate to form oxaloacetate, Cl-, and NH4. The enzyme was active toward only threo-3-chloro-L-aspartate and L-cysteine, but did not catalyze a beta-replacement reaction. The enzyme can be classified in a new group of PLP-dependent amino acid-lyases [EC 4.2.1.-].
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Affiliation(s)
- Y Kato
- Biotechnology Research Center, Faculty of Engineering, Toyama Prefectural University, Kosugi, Japan
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Kato S, Mihara H, Kurihara T, Yoshimura T, Esaki N. Gene cloning, purification, and characterization of two cyanobacterial NifS homologs driving iron-sulfur cluster formation. Biosci Biotechnol Biochem 2000; 64:2412-9. [PMID: 11193410 DOI: 10.1271/bbb.64.2412] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [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: 11/08/2022]
Abstract
Iron-sulfur proteins are essential in the photosynthetic system and many other biological processes. We have isolated and characterized enzymes driving the formation of iron-sulfur clusters from Synechocystis sp. PCC6803. Two genes (slr0387 and sll0704), showing similarity to nifS of Azotobacter vinelandii, were cloned, and their gene products (SsCsdl and SsCsd2) were purified. They catalyzed the desulfuration of L-cysteine. Reconstitution of a [2Fe-2S] cluster of cyanobacterial ferredoxin proceeded much faster in the presence of L-cysteine and either of these enzymes than when using sodium sulfide. These results suggest that SsCsdl and SsCsd2 facilitate the iron-sulfur cluster assembly by producing inorganic sulfur from L-cysteine. Synechocystis sp. PCC6803 has no gene coding for a protein with similarity to the N-terminal domain of NifU of A. vinelandii, which is believed to cooperate with NifS to assemble iron-sulfur clusters. Thus, the cluster formation in the cyanobacterium probably proceeds through a mechanism that is different from that in A. vinelandii.
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Affiliation(s)
- S Kato
- Institute for Chemical Research, Kyoto University, Japan
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Abstract
Diverse organisms ranging from Escherichia coli to humans contain a variety of DNA repair proteins that function in the removal of damage caused by shortwave UV light. This study reports the identification, purification, and biochemical characterization of two DNA glycosylases with associated abasic lyase activity from Neisseria mucosa. These enzymes, pyrimidine dimer glycosylase I and II (Nmu-pdg I and Nmu-pdg II), were purified 30,000- and 10,000-fold, respectively. SDS-polyacrylamide gel electrophoresis analysis indicated that Nmu-pdg I is approximately 30 kDa, whereas Nmu-pdg II is approximately 19 kDa. The N-terminal amino acid sequence of Nmu-pdg II exhibits 64 and 66% identity with E. coli and Hemophilus parainfluenzae endonuclease III, respectively. Both Nmu-pdg I and Nmu-pdg II were found to have broad substrate specificities, as evidenced by their ability to incise DNA containing many types of UV and some types of oxidative damage. Consistent with other glycosylase/abasic lyases, the existence of a covalent enzyme-DNA complex could be demonstrated for both Nmu-pdg I and II when reactions were carried out in the presence of sodium borohydride. These data indicate the involvement of an amino group in the catalytic reaction mechanism of both enzymes.
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Affiliation(s)
- S G Nyaga
- Center for Molecular Science, the University of Texas Medical Branch, Galveston, Texas 77555, USA
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31
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Commandeur JN, Andreadou I, Rooseboom M, Out M, de Leur LJ, Groot E, Vermeulen NP. Bioactivation of selenocysteine Se-conjugates by a highly purified rat renal cysteine conjugate beta-lyase/glutamine transaminase K. J Pharmacol Exp Ther 2000; 294:753-61. [PMID: 10900257] [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: 02/17/2023] Open
Abstract
Selenocysteine Se-conjugates have recently been proposed as potential prodrugs to target pharmacologically active selenol compounds to the kidney. Although rat renal cytosol displayed a high activity of beta-elimination activity toward these substrates, the enzymes involved in this activation pathway as yet have not been identified. In the present study, the possible involvement of cysteine conjugate beta-lyase/glutamine transaminase K (beta-lyase/GTK) in cytosolic activity was investigated. To this end, the enzyme kinetics of 15 differentially substituted selenocysteine Se-conjugates and 11 cysteine S-conjugates was determined using highly purified rat renal beta-lyase/GTK. The results demonstrate that most selenocysteine Se-conjugates are beta-eliminated at a very high activity by purified beta-lyase/GTK, implicating an important role of this protein in the previously reported beta-elimination reactions in rat renal cytosol. As indicated by the rapid consumption of alpha-keto-gamma-methiolbutyric acid, purified beta-lyase/GTK also catalyzed transamination reactions, which appeared to even exceed that of beta-elimination. The corresponding sulfur analogs also showed significant transamination but were beta-eliminated at an extremely low rate. Comparison of the obtained enzyme kinetic data of purified beta-lyase/GTK with previously obtained data from rat renal cytosol showed a poor correlation. By determining the activity profiles of cytosolic fractions applied to anion exchange fast protein liquid chromatography and gel filtration chromatography, the involvement of multiple enzymes in the beta-elimination of selenocysteine Se-conjugates in rat renal cytosol was demonstrated. The identity and characteristics of these alternative selenocysteine conjugate beta-lyases, however, remain to be established.
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Affiliation(s)
- J N Commandeur
- Leiden/Amsterdam Center for Drug Research, Division of Molecular Toxicology, Department of Pharmacochemistry, Vrije Universiteit Amsterdam, The Netherlands.
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Warrilow AG, Hawkesford MJ. Cysteine synthase (O-acetylserine (thiol) lyase) substrate specificities classify the mitochondrial isoform as a cyanoalanine synthase. J Exp Bot 2000; 51:985-993. [PMID: 10948226 DOI: 10.1093/jexbot/51.347.985] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A cyanoalanine synthase and two isoforms (A, cytosolic and B, chloroplastic) of cysteine synthase (O:-acetylserine (thiol) lyase) were isolated from spinach. N-terminal amino acid sequence analysis of the cyanoalanine synthase gave 100% homology for the determined 12 residues with a published sequence for the mitochondrial cysteine synthase isoform. All three enzymes catalysed both the cysteine synthesis and cyanoalanine synthesis reactions, although with different efficiencies. Michaelis-Menten kinetics were observed for all three enzymes when substrate saturation experiments were performed varying O:-acetylserine, chloroalanine and cysteine. Negative co-operative kinetics were observed for cysteine synthases A and B when substrate saturation experiments were performed varying sulphide and cyanide, compared with the Michaelis-Menten kinetics observed for cyanoalanine synthase. The exception was negative co-operativity observed towards sulphide for cyanoalanine synthase with O:-acetylserine as co-substrate. The optimum sulphide concentration was dependent on the alanyl co-substrate used. The amino acid sequence similarity places these three enzymes in the same gene family, and whilst the close kinetic similarities support this, they also indicate distinct roles for the isoforms.
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Affiliation(s)
- A G Warrilow
- IACR-Rothamsted, Biochemistry and Physiology Department, Harpenden, Hertfordshire AL5 2JQ, UK
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Prapanthadara L, Promtet N, Koottathep S, Somboon P, Ketterman AJ. Isoenzymes of glutathione S-transferase from the mosquito Anopheles dirus species B: the purification, partial characterization and interaction with various insecticides. Insect Biochem Mol Biol 2000; 30:395-403. [PMID: 10745163 DOI: 10.1016/s0965-1748(00)00013-8] [Citation(s) in RCA: 18] [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: 05/23/2023]
Abstract
Previously we have purified and characterized a major glutathione S-transferase (GST) activity, GST-4a, from the Thai mosquito Anopheles dirus B, a model mosquito for study of anopheline malaria vectors [Prapanthadara, L. Koottathep, S., Promtet, N., Hemingway, J. and Ketterman, A.J. (1996) Insect Biochem. Mol. Biol. 26:3, 277-285]. In this report we have purified an isoenzyme, GST-4c, which has the greatest DDT-dehydrochlorinase activity. Three additional isoenzymes, GST-4b, GST-5 and GST-6, were also partially purified and characterized for comparison. All of the Anopheles GST isoenzymes preferred 1-chloro-2,4-dinitrobenzene (CDNB) as an electrophilic substrate. In kinetic studies with CDNB as an electrophilic substrate, the V(max) of GST-4c was 24.38 micromole/min/mg which was seven-fold less than GST-4a. The two isoenzymes also possessed different K(m)s for CDNB and glutathione. Despite being only partially pure GST-4b had nearly a four-fold greater V(max) for CDNB than GST-4c. In contrast, GST-4c possessed the greatest DDT-dehydrochlorinase specific activity among the purified insect GST isoenzymes and no activity was detected for GST-5. Seven putative GST substrates used in this study were not utilized by An. dirus GSTs, although they were capable of inhibiting CDNB conjugating activity to different extents for the different isoenzymes. Bromosulfophthalein and ethacrynic acid were the most potent inhibitors. The inhibition studies demonstrate different degrees of interaction of the An. dirus isoenzymes with various insecticides. The GSTs were inhibited more readily by organochlorines and pyrethroids than by the phosphorothioates and carbamate. In a comparison between An. dirus and previous data from An. gambiae the two anopheline species possess a similar pattern of GST isoenzymes although the individual enzymes differ significantly at the functional level. The available data suggests there may be a minimum of three GST classes in anopheline insects.
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Affiliation(s)
- L Prapanthadara
- Research Institute for Health Sciences, Chiangmai University, Chiangmai, Thailand.
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Yamaguchi Y, Nakamura T, Kusano T, Sano H. Three Arabidopsis genes encoding proteins with differential activities for cysteine synthase and beta-cyanoalanine synthase. Plant Cell Physiol 2000; 41:465-476. [PMID: 10845460 DOI: 10.1093/pcp/41.4.465] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Three cDNA clones encoding putative cysteine synthases (O-acetylserine (thiol) lyase, EC 4.2.99.8) were isolated from Arabidopsis thaliana and designated AtcysC1, AtcysD1 and AtcysD2, respectively. Southern blot analyses suggested that the corresponding genes were present as a single copy, or at most two copies, in the A. thaliana genome. Escherichia coli complementation analyses confirmed that the cDNAs encode cysteine synthase and the corresponding proteins produced in E. coli clearly showed cysteine synthase activity. In addition, AtcysC1 protein showed beta-cyanoalanine synthase (EC 4.4.1.9) activity, but the other two did not. Kinetic analysis suggests that AtcysC1 actually functions as beta-cyanoalanine synthase rather than cysteine synthase in vivo. The mRNA accumulation of AtcysC1, AtcysD1 and AtcysD2 differed in various organs, but did not change markedly when A. thaliana seedlings were subjected to various stresses, including nutrient deprivation. In vivo targeting experiments indicated that AtcysD1 and AtcysD2 are cytoplasmic isozymes, and AtcysC1 is a mitochondrial isozyme.
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Affiliation(s)
- Y Yamaguchi
- Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Ikoma, Japan
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Mihara H, Kurihara T, Watanabe T, Yoshimura T, Esaki N. cDNA cloning, purification, and characterization of mouse liver selenocysteine lyase. Candidate for selenium delivery protein in selenoprotein synthesis. J Biol Chem 2000; 275:6195-200. [PMID: 10692412 DOI: 10.1074/jbc.275.9.6195] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [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: 11/06/2022] Open
Abstract
Selenocysteine lyase (SCL) (EC 4.4.1.16) is a pyridoxal 5'-phosphate-dependent enzyme that specifically catalyzes the decomposition of L-selenocysteine to L-alanine and elemental selenium. The enzyme was proposed to function as a selenium delivery protein to selenophosphate synthetase in selenoprotein biosynthesis (Lacourciere, G. M., and Stadtman, T. C. (1998) J. Biol. Chem. 273, 30921-30926). We purified SCL from pig liver and determined its partial amino acid sequences. Mouse cDNA clones encoding peptides resembling pig SCL were found in the expressed sequence tag data base, and their sequences were used as probes to isolate full-length mouse liver cDNA. The cDNA for mouse SCL (mSCL) was determined to be 2,172 base pairs in length, containing an open reading frame encoding a polypeptide chain of 432 amino acid residues (M(r) 47, 201). We also determined the sequence of the N-terminal region of putative human SCL. These enzymes were shown to be distantly related in primary structure to NifS, which catalyzes the desulfurization of L-cysteine to provide sulfur for iron-sulfur clusters. The recombinant mSCL overproduced in Escherichia coli was a homodimer with the subunit M(r) of 47,000. The enzyme was pyridoxal phosphate-dependent and highly specific to L-selenocysteine (the k(cat)/K(m) value for L-selenocysteine was about 4,200 times higher than that for L-cysteine). Reverse transcriptase-polymerase chain reaction and Western blot analyses revealed that mSCL is cytosolic and predominantly exists in the liver, kidney, and testis, where mouse selenophosphate synthetase is also abundant, supporting the view that mSCL functions in cooperation with selenophosphate synthetase in selenoprotein synthesis. This is the first report of the primary structure of mammalian SCL.
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Affiliation(s)
- H Mihara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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Maruyama A, Ishizawa K, Takagi T. Purification and characterization of beta-cyanoalanine synthase and cysteine synthases from potato tubers: are beta-cyanoalanine synthase and mitochondrial cysteine synthase same enzyme? Plant Cell Physiol 2000; 41:200-208. [PMID: 10795315 DOI: 10.1093/pcp/41.2.200] [Citation(s) in RCA: 10] [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: 05/23/2023]
Abstract
beta-Cyanoalanine synthase (CAS; EC 4.4.1.9) and two kinds of cysteine synthases (CS; EC 4.2.99.8) have been purified from the particulate fraction of potato tubers. By DEAE Sephacel and Resource PHE chromatography, CAS activity was separated from two CS activities, designated as CS-1 and CS-2. The molecular masses of CAS, CS-1 and CS-2 were estimated to be 37, 39 and 34 kDa, respectively, by SDS-PAGE analysis. The purified CAS had CS activity, and both CS-1 and CS-2 had CAS activity. However, CAS and CSs had significant differences in kinetic characters. The antibody raised against purified CAS discriminated CAS from CSs, whereas the antibody raised against purified CS-2 recognized CS-1 and CS-2 but not CAS. The molecular mass and the partial amino acid sequence of CS-2 were similar to those of the cytosolic CS of potato, whereas the molecular mass of CS-1 was similar to that of the plastidic CS. The partial amino acid sequence of CAS was similar to those of CS isozymes, especially the mitochondrial CS isolated from spinach.
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Affiliation(s)
- A Maruyama
- Biological Institute, Graduate School of Science, Tohoku University, Sendai, Japan
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Kato Y, Nakamura K, Sakiyama H, Mayhew SG, Asano Y. Novel heme-containing lyase, phenylacetaldoxime dehydratase from Bacillus sp. strain OxB-1: purification, characterization, and molecular cloning of the gene. Biochemistry 2000; 39:800-9. [PMID: 10651646 DOI: 10.1021/bi991598u] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [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: 11/30/2022]
Abstract
A novel dehydratase that catalyzes the stoichiometric dehydration of Z-phenylacetaldoxime to phenylacetonitrile has been purified 483-fold to homogeneity from a cell-free extract of Bacillus sp. strain OxB-1 isolated from soil. It has a M(r) of about 40 000 and is composed of a single polypeptide chain with a loosely bound protoheme IX. The enzyme is inactive unless FMN is added to the assay, but low activity is also observed when sulfite replaces FMN. The activity in the presence of FMN is enhanced 5-fold under anaerobic conditions compared to the activity measured in air. The enzyme has maximum activity at pH 7.0 and 30 degrees C, and it is stable at up to 45 degrees C at around neutral pH. The aerobically measured activity in the presence of FMN is also enhanced by Fe(2+), Sn(2+), SO(3)(2)(-), and NaN(3). Metal-chelating reagents, carbonyl reagents, electron donors, and ferri- and ferrocyanides strongly inhibit the enzyme with K(i) values in the micromolar range. The enzyme is active with arylalkylaldoximes and to a lesser extent with alkylaldoximes. The enzyme prefers the Z-form of phenylacetaldoxime over its E-isomer. On the basis of its substrate specificity, the enzyme has been tentatively named phenylacetaldoxime dehydratase. The gene coding for the enzyme was cloned into plasmid pUC18, and a 1053 base-pair open reading frame that codes for 351 amino acid residues was identified as the oxd gene. A nitrilase, which participates in aldoxime metabolism in the organism, was found to be coded by the region just upstream from the oxd gene. In addition an open reading frame (orf2), whose gene product is similar to bacterial regulatory (DNA-binding) proteins, was found just upstream from the coding region of the nitrilase. These findings provide genetic evidence for a novel gene cluster that is responsible for aldoxime metabolism in this microorganism.
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Affiliation(s)
- Y Kato
- Biotechnology Research Center, Toyama Prefectural University, Kosugi, Toyama 939-0398, Japan
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Mihara H, Maeda M, Fujii T, Kurihara T, Hata Y, Esaki N. A nifS-like gene, csdB, encodes an Escherichia coli counterpart of mammalian selenocysteine lyase. Gene cloning, purification, characterization and preliminary x-ray crystallographic studies. J Biol Chem 1999; 274:14768-72. [PMID: 10329673 DOI: 10.1074/jbc.274.21.14768] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.1] [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: 11/06/2022] Open
Abstract
Selenocysteine lyase is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the exclusive decomposition of L-selenocysteine to L-alanine and elemental selenium. An open reading frame, named csdB, from Escherichia coli encodes a putative protein that is similar to selenocysteine lyase of pig liver and cysteine desulfurase (NifS) of Azotobacter vinelandii. In this study, the csdB gene was cloned and expressed in E. coli cells. The gene product was a homodimer with the subunit Mr of 44,439, contained 1 mol of PLP as a cofactor per mol of subunit, and catalyzed the release of Se, SO2, and S from L-selenocysteine, L-cysteine sulfinic acid, and L-cysteine, respectively, to yield L-alanine; the reactivity of the substrates decreased in this order. Although the enzyme was not specific for L-selenocysteine, the high specific activity for L-selenocysteine (5.5 units/mg compared with 0.019 units/mg for L-cysteine) supports the view that the enzyme can be regarded as an E. coli counterpart of mammalian selenocysteine lyase. We crystallized CsdB, the csdB gene product, by the hanging drop vapor diffusion method. The crystals were of suitable quality for x-ray crystallography and belonged to the tetragonal space group P43212 with unit cell dimensions of a = b = 128.1 A and c = 137.0 A. Consideration of the Matthews parameter Vm (3.19 A3/Da) accounts for the presence of a single dimer in the crystallographic asymmetric unit. A native diffraction dataset up to 2.8 A resolution was collected. This is the first crystallographic analysis of a protein of NifS/selenocysteine lyase family.
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Affiliation(s)
- H Mihara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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Jia YJ, Kakuta Y, Sugawara M, Igarashi T, Oki N, Kisaki M, Shoji T, Kanetuna Y, Horita T, Matsui H, Honma M. Synthesis and degradation of 1-aminocyclopropane-1-carboxylic acid by Penicillium citrinum. Biosci Biotechnol Biochem 1999; 63:542-9. [PMID: 10227140 DOI: 10.1271/bbb.63.542] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.0] [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: 11/08/2022]
Abstract
1-Aminocyclopropane-1-carboxylic acid (ACC), which is a precursor of ethylene in plants, has never been known to occur in microorganisms. We describe the synthesis of ACC by Penicillium citrinum, purification of ACC synthase [EC 4.4.1.14] and ACC deaminase [EC 4.1.99.4], and their properties. Analyses of P. citrinum culture showed occurrence of ACC in the culture broth and in the cell extract. ACC synthase was purified from cells grown in a medium containing 0.05% L-methionine and ACC deaminase was done from cells incubated in a medium containing 1% 2-aminoisobutyrate. The purified ACC synthase, with a specific activity of 327 milliunit/mg protein, showed a single band of M(r) 48,000 in SDS-polyacrylamide gel electrophoresis. The molecular mass of the native enzyme by gel filtration was 96,000 Da. The ACC synthase had the Km for S-adenosyl-L-methionine of 1.74 mM and kcat of 0.56 s-1 per monomer. The purified ACC deaminase, with a specific activity of 4.7 unit/mg protein, showed one band in SDS-polyacrylamide gel electrophoresis of M(r) 41,000. The molecular mass of the native ACC deaminase was 68,000 Da by gel filtration. The enzyme had a Km for ACC of 4.8 mM and kcat of 3.52 s-1. The presence of 7 mM Cu2+ in alkaline buffer solution was effective for increasing the stability of the ACC deaminase in the process of purification.
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Affiliation(s)
- Y J Jia
- Faculty of Agriculture, Hokkaido University, Sapporo, Japan.
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Kudo F, Hosomi Y, Tamegai H, Kakinuma K. Purification and characterization of 2-deoxy-scyllo-inosose synthase derived from Bacillus circulans. A crucial carbocyclization enzyme in the biosynthesis of 2-deoxystreptamine-containing aminoglycoside antibiotics. J Antibiot (Tokyo) 1999; 52:81-8. [PMID: 10344560 DOI: 10.7164/antibiotics.52.81] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [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: 11/21/2022]
Abstract
The biosynthesis of 2-deoxystreptamine, the central aglycon of a major group of clinically important aminoglycoside antibiotics, commences with the initial carbocycle formation step from D-glucose-6-phosphate to 2-deoxy-scyllo-inosose. This crucial step is known to be catalyzed by 2-deoxy-scyllo-inosose synthase, which has not yet been characterized so far. Reported in this paper is the first purification of 2-deoxy-scyllo-inosose synthase from butirosin-producing Bacillus circulans SANK 72073 to electrophoretic homogeneity. The enzyme was isolated as a heterodimeric protein comprising from a 23 kDa- and a 42 kDa polypeptide chains. The Km of the enzyme for D-glucose-6-phosphate was estimated to be 9.0 x 10(-4) M and that for NAD+ 1.7 x 10(-4) M, kcat for D-glucose-6-phosphate being 7.3 x 10(-2) s(-1). The presence of Co2+ was essential for the enzyme activity, but Zn2+ was totally inhibitory. While the reaction mechanisms are quite similar, 2-deoxy-scyllo-inosose synthase appears to be distinct from dehydroquinate synthase in the shikimate pathway, with respect to the quaternary structure, metal ion requirement, and the kinetic parameters.
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Affiliation(s)
- F Kudo
- Department of Chemistry, Tokyo Institute of Technology, Japan
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41
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Gibson LC, Jensen PE, Hunter CN. Magnesium chelatase from Rhodobacter sphaeroides: initial characterization of the enzyme using purified subunits and evidence for a BchI-BchD complex. Biochem J 1999; 337 ( Pt 2):243-51. [PMID: 9882621 PMCID: PMC1219958] [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: 02/09/2023]
Abstract
The enzyme magnesium-protoporphyrin IX chelatase (Mg chelatase) catalyses the insertion of Mg into protoporphyrin IX, the first committed step in (bacterio)chlorophyll biosynthesis. In the photosynthetic bacterium Rhodobacter sphaeroides, this reaction is catalysed by the products of the bchI, bchD and bchH genes. These genes have been expressed in Escherichia coli so that the BchI, BchD and BchH proteins are produced with N-terminal His6 affinity tags, which has led to the production of large amounts of highly purified, highly active Mg chelatase subunits from a single chromatography step. Furthermore, BchD has been purifed free of contamination with the chaperone GroEL, which had proven to be a problem in the past. BchD, present largely as an insoluble protein in E. coli, was purified in 6 M urea and refolded by addition of BchI, MgCl2 and ATP, yielding highly active protein. BchI/BchD mixtures prepared in this way were used in conjunction with BchH to determine the kinetic parameters of R. sphaeroides Mg chelatase for its natural substrates. We have been able to demonstrate for the first time that BchI and BchD form a complex, and that Mg2+ and ATP are required to establish and maintain this complex. Gel filtration data suggest that BchI and BchD form a complex of molecular mass 200 kDa in the presence of Mg2+ and ATP. Our data suggest that, in vivo, BchD is only folded correctly and maintained in its correct conformation in the presence of BchI, Mg2+ and ATP.
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Affiliation(s)
- L C Gibson
- Krebs Institute for Biomolecular Research and Robert Hill Institute for Photosynthesis, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K.
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Cai B, Vuilleumier S, Wackett LP. Purification and characterization of the mutant enzyme W117Y of the dichloromethane dehalogenase from Methylophilus sp. strain DM11. Ann N Y Acad Sci 1998; 864:210-3. [PMID: 10075637 DOI: 10.1111/j.1749-6632.1998.tb10307.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- B Cai
- Institute of Molecular Biology, Nankai University, Tianjin 30071, China
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Zhou H, Huxtable S, Xin H, Li N. Enhanced high-level expression of soluble 1-aminocyclopropane-1-carboxylase synthase and rapid purification by expanded-bed adsorption. Protein Expr Purif 1998; 14:178-84. [PMID: 9790879 DOI: 10.1006/prep.1998.0923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [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: 11/22/2022]
Abstract
1-Aminocyclopropane-1-carboxylate (ACC) synthase is a key enzyme regulating the biosynthesis of the plant hormone ethylene. Expression of ACC synthase in Escherichia coli can result in the production of a large proportion of the enzyme in the form of insoluble aggregates (inclusion bodies). We investigated the effect on the soluble expression in E. coli of tomato and zucchini ACC synthases, by manipulation of the induction conditions, changing the vector, and deletions in the amino acid sequence. Manipulation of the induction conditions did not influence the soluble expression; however, soluble expression increased significantly when the enzyme was cloned into vector pET11d, in comparison to the other vector used, pET30a. It was also found that when ACC synthase with a portion of the C-terminus deleted was inserted into pET11d, the soluble expression was further enhanced in comparison to that of the full length. Structural and functional analysis of ACC synthase requires the purification of milligram quantities of protein to homogeneity. The development of a faster and simpler protocol for the purification of ACC synthase is highly desirable due to the extreme lability of the enzyme. C-terminal truncated tomato ACC synthase was overexpressed in E. coli pET11d and purified by expanded-bed adsorption and hydroxylapatite FPLC. This improved two-step purification protocol allows for rapid, high-level purification with a significantly improved yield in comparison to the multistage purification it replaces. 15.7 mg of highly purified tomato ACC synthase del-1 were obtained from 2 L of cells in comparison to 2 mg from 10 L using a multistage purification. This represents a 40-fold improvement in yield. Antibodies were raised against C-terminal deleted ACC synthase. The antibodies were purified by epitope-specific affinity chromatography and used to assess the identity and purity of the C-terminal-deleted tomato ACC synthase purified by expanded-bed adsorption.
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Affiliation(s)
- H Zhou
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
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Zaborina O, Daubaras DL, Zago A, Xun L, Saido K, Klem T, Nikolic D, Chakrabarty AM. Novel pathway for conversion of chlorohydroxyquinol to maleylacetate in Burkholderia cepacia AC1100. J Bacteriol 1998; 180:4667-75. [PMID: 9721310 PMCID: PMC107482 DOI: 10.1128/jb.180.17.4667-4675.1998] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [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] [Received: 04/01/1998] [Accepted: 06/08/1998] [Indexed: 11/20/2022] Open
Abstract
Burkholderia cepacia AC1100 metabolizes 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) via formation of 5-chlorohydroxyquinol (5-CHQ), hydroxyquinol (HQ), maleylacetate, and beta-oxoadipate. The step(s) leading to the dechlorination of 5-CHQ to HQ has remained unidentified. We demonstrate that a dechlorinating enzyme, TftG, catalyzes the conversion of 5-CHQ to hydroxybenzoquinone, which is then reduced to HQ by a hydroxybenzoquinone reductase (HBQ reductase). HQ is subsequently converted to maleylacetate by hydroxyquinol 1,2-dioxygenase (HQDO). All three enzymes were purified. We demonstrate specific product formation by colorimetric assay and mass spectrometry when 5-CHQ is treated successively with the three enzymes: TftG, TftG plus HBQ reductase, and TftG plus HBQ reductase plus HQDO. This study delineates the complete enzymatic pathway for the degradation of 5-CHQ to maleylacetate.
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Affiliation(s)
- O Zaborina
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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Maruyama A, Ishizawa K, Takagi T, Esashi Y. Cytosolic beta-cyanoalanine synthase activity attributed to cysteine synthases in cocklebur seeds. Purification and characterization of cytosolic cysteine synthases. Plant Cell Physiol 1998; 39:671-680. [PMID: 9729892 DOI: 10.1093/oxfordjournals.pcp.a029421] [Citation(s) in RCA: 14] [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: 05/22/2023]
Abstract
The activity of beta-cyanoalanine synthase (CAS, EC 4.4.1.9) in cotyledons of cocklebur seeds (Xanthium pennsylvanicum Wallr.) was detected both in the soluble and particulate fractions. The CAS activity of the soluble fraction (cytosolic CAS activity) was 10 times higher than that of the particulate fraction. The CAS activity of the particulate fraction was confirmed to be localized in the mitochondria. Both enzymatic activities were clearly separated by non-denaturing PAGE. The enzyme with cytosolic CAS activity has been extensively purified and separated into three different forms designated as cyt-1, cyt-2, and cyt-3. According to the SDS-PAGE analysis, the three enzymes are estimated to be a homodimer composed of 35-kDa subunits. The purified enzymes showed CS activity. Partial amino acid sequences of cyt-1 were determined and had a high homology with cysteine synthases (CS, EC 4.2.99.8) from other plant sources. The catalytic action of the purified CSs in converting cyanide and cysteine into H2S and beta-cyanoalanine was confirmed by the detection of significant 14CN incorporation into beta-cyanoalanine. These results indicated that cytosolic CAS activity is due to cytosolic CS and suggested that the CAS activity of CS is likely to be involved in cyanide metabolism in plant tissues.
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Affiliation(s)
- A Maruyama
- Biological Institute, Graduate School of Science, Tohoku University, Senda, Japan
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Huxtable S, Zhou H, Wong S, Li N. Renaturation of 1-aminocyclopropane-1-carboxylate synthase expressed in Escherichia coli in the form of inclusion bodies into a dimeric and catalytically active enzyme. Protein Expr Purif 1998; 12:305-14. [PMID: 9535697 DOI: 10.1006/prep.1997.0847] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [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: 11/22/2022]
Abstract
1-Aminocyclopropane-1-carboxylate (ACC) synthase is a key enzyme regulating the biosynthesis of the plant hormone ethylene. A wound-inducible zucchini ACC synthase cDNA was isolated by reverse-transcription polymerase chain reaction (RT-PCR) and expressed in a heterologous Escherichia coli BL21(DE3)pLysS:pET30a protein expression system. A method was developed and optimized for the renaturation of the ACC synthase expressed in the form of inclusion bodies. The optimum conditions were found to be unfolding in a buffer containing 100 mM Mops, pH 9.5, 6 M urea, and 50 mM DTT, for 3 h at 4 degrees C and refolding by a combined process of dialysis and dilution in 100 mM Mops, pH 8, 30 mM Chaps, and 5 mM GSH at a protein concentration of 45 microg/ml. The purified enzyme has a specific activity of 90,000 U mg-1 and exhibits an apparent homogeneity on SDS-PAGE fractionation. Biochemical characterization of the refolded enzyme revealed a high degree of similarity to the enzyme purified from the soluble source. The refolded enzyme was found to be a dimer with a native size of 110 kDa, a Km of 23 microM, and a Vmax of 112,000 U mg-1.
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Affiliation(s)
- S Huxtable
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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Abstract
The endogenous neuroprotectant kynurenic acid (KYNA) is produced by irreversible transamination of L-kynurenine (KYN). In the brain, two distinct kynurenine aminotransferases (KAT I and KAT II) are responsible for the formation of KYNA. The present experiments were designed to examine the respective roles of the two KATs in the normal rat brain. To this end, the two enzymes were partially purified, and their characteristics were examined. KAT I (identical with glutamine transaminase K) had an optimal pH of 9.5, preferred pyruvate as a cosubstrate and was potently inhibited by glutamine. KAT II (identical with L-alpha-aminoadipate transaminase) had a neutral optimal pH, showed no preference for pyruvate, and was essentially insensitive to inhibition by glutamine. KAT II was selectively inhibited by quisqualic acid (IC50: 520 microM). The endogenous substrate 3-hydroxykynurenine had an approximately 10-fold preference for KAT II. The distinct properties of the two enzymes made it possible to measure brain KAT I and KAT II in parallel by using dialyzed tissue homogenate (to remove interfering endogenous amino acids). Under these conditions, both enzymes presented essentially the same apparent Km values as the partially purified enzymes. In lesioned, neurondepleted brain tissue and in brain regions other than the cerebellum, KYNA derived primarily from KAT II at physiologic pH. In summary, the present study describes a simple methodology for the simultaneous determination of the two KYNA-producing enzymes in small rat brain tissue samples and provides baseline values for future work in experimentally challenged animals.
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Affiliation(s)
- P Guidetti
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore 21228, USA
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48
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Abstract
Prenylated proteins contain one of two isoprenoid lipids, either the 15-carbon farnesyl or the 20-carbon geranylgeranyl, covalently attached to cysteine residues at or near their C terminus. The cellular abundance of prenylated proteins, which can comprise up to 2% of total cellular protein, raises the question of how cells dispose of prenylcysteines produced during the normal turnover of prenylated proteins. We have identified and characterized a novel enzyme, which we term prenylcysteine lyase, that is capable of cleaving the thioether bond of prenylcysteines. The enzyme was isolated from bovine brain membranes and exhibits an apparent molecular mass of 63 kDa. The enzyme did not require NADPH as cofactor for prenylcysteine degradation, thus distinguishing it from cytochrome P450- and flavin-containing monooxygenases that catalyze S-oxidation of thioethers. Purified prenylcysteine lyase shows similar kinetics in utilization of both farnesylcysteine and geranylgeranylcysteine as substrates, although Vmax is 2-fold higher with the former compound. Interaction of prenylcysteine substrates with the enzyme requires that they possess a free amino group; N-acetylated prenylcysteines and prenyl peptides are not substrates. These findings suggest that prenylcysteine lyase is a specific enzyme involved in prenylcysteine metabolism in mammalian cells, most likely comprising the final step in the degradation of prenylated proteins.
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Affiliation(s)
- L Zhang
- Department of Molecular Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710-3686, USA
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49
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Mihara H, Kurihara T, Yoshimura T, Soda K, Esaki N. Cysteine sulfinate desulfinase, a NIFS-like protein of Escherichia coli with selenocysteine lyase and cysteine desulfurase activities. Gene cloning, purification, and characterization of a novel pyridoxal enzyme. J Biol Chem 1997; 272:22417-24. [PMID: 9278392 DOI: 10.1074/jbc.272.36.22417] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.6] [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
Selenocysteine lyase (EC 4.4.1.16) exclusively decomposes selenocysteine to alanine and elemental selenium, whereas cysteine desulfurase (NIFS protein) of Azotobacter vinelandii acts indiscriminately on both cysteine and selenocysteine to produce elemental sulfur and selenium respectively, and alanine. These proteins exhibit some sequence homology. The Escherichia coli genome contains three genes with sequence homology to nifS. We have cloned the gene mapped at 63.4 min in the chromosome and have expressed, purified to homogeneity, and characterized the gene product. The enzyme comprises two identical subunits with 401 amino acid residues (Mr 43,238) and contains pyridoxal 5'-phosphate as a coenzyme. The enzyme catalyzes the removal of elemental sulfur and selenium atoms from L-cysteine, L-cystine, L-selenocysteine, and L-selenocystine to produce L-alanine. Because L-cysteine sulfinic acid was desulfinated to form L-alanine as the preferred substrate, we have named this new enzyme cysteine sulfinate desulfinase. Mutant enzymes having alanine substituted for each of the four cysteinyl residues (Cys-100, Cys-176, Cys-323, and Cys-358) were all active. Cys-358 corresponds to Cys-325 of A. vinelandii NIFS, which is conserved among all NIFS-like proteins and catalytically essential (Zheng, L., White, R. H., Cash, V. L., and Dean, D. R. (1994) Biochemistry 33, 4714-4720), is not required for cysteine sulfinate desulfinase. Thus, the enzyme is distinct from A. vinelandii NIFS in this respect.
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Affiliation(s)
- H Mihara
- Laboratory of Microbial Biochemistry, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611, Japan
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50
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Nakagawa Y, Watanabe S, Akiyama K, Sarker AH, Tsutsui K, Inoue H, Seki S. cDNA cloning, sequence analysis and expression of a mouse 44-kDa nuclear protein copurified with DNA repair factors for acid-depurinated DNA. Acta Med Okayama 1997; 51:195-206. [PMID: 9284967 DOI: 10.18926/amo/30763] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We purified a 44-kDa nuclear protein from salt-extract of permeable mouse ascites sarcoma cells in an effort to isolate factors involved in the repair of acid-depurinated DNA. It was copurified with a major AP endonuclease (APEX nuclease) by sequential column chromatography then further purified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis as a possible DNA repair support factor. Its partial amino acid sequences were determined, and a cDNA clone for the protein was isolated from a mouse T-cell cDNA library using long degenerate oligonucleotide probes deduced from the amino acid sequence. The complete nucleotide sequence of the cDNA (1.7 kilobases) was determined. Northern hybridization using this cDNA detected two transcripts: 1.8 kb being the major one and 2.6 kb being the minor one. The complete amino acid sequence for the protein predicted from the nucleotide sequence of the cDNA indicates that the 44-kDa protein consists of 394 amino acids with a calculated molecular weight of 43,698. In tests performed thus far, the recombinant 44-kDa protein expressed in Escherichia coli has not expressed any repair-support activity. It remains to be analyzed whether the protein attains this activity after appropriate posttranslational modifications. Most parts of the 44-kDa protein cDNA and the deduced amino acid sequence were found to be identical to those of the protein p38-2G4, recently reported as a cell cycle-specifically modulated nuclear protein of 38kDa. The p38-2G4 may be a truncated form of the present 44-kDa protein.
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Affiliation(s)
- Y Nakagawa
- Department of Molecuclar Biology, Okayama University Medical School, Japan
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