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Thermotoga Maritima (thermotoga + maritima)
Kinds of Thermotoga Maritima Selected AbstractsTargeting clusters of transferred genes in Thermotoga maritimaENVIRONMENTAL MICROBIOLOGY, Issue 11 2003Camilla L. Nesbø Summary We screened a Thermotoga sp. strain RQ2 lambda library for genes present in that strain but absent from the closely related completely sequenced relative Thermotoga maritima strain MSB8, by using probes generated in an earlier genomic subtraction study. Five lambda insert fragments were sequenced, containing, respectively, an archaeal type ATPase operon, rhamnose biosynthetic genes, ORFs with similarity to an arabinosidase, a Thermotoga sp. strain RQ2-specific alcohol dehydrogenase and a novel archaeal Mut-S homologue. All but one of these fragments contained additional Thermotoga sp. strain RQ2-specific sequences not screened for, suggesting that many such strain-specific genes will be found clustered in the genome. Moreover, phylogenetic analyses, phylogenetic distribution and/or G + C content suggests that all the Thermotoga sp. strain RQ2 specific sequences in the sequenced lambda clones have been acquired by lateral gene transfer. We suggest that the use of strain-specific small insert clones obtained by subtractive hybridization to target larger inserts for sequencing is an efficient, economical way to identify environmentally (or clinically) relevant interstrain differences and novel gene clusters, and will be invaluable in comparative genomics. [source] Characterization and mode of action of an exopolygalacturonase from the hyperthermophilic bacterium Thermotoga maritimaFEBS JOURNAL, Issue 21 2005Leon D. Kluskens An intracellular pectinolytic enzyme, PelB (TM0437), from the hyperthermophilic bacterium Thermotoga maritima was functionally produced in Escherichia coli and purified to homogeneity. PelB belongs to family 28 of the glycoside hydrolases, consisting of pectin-hydrolysing enzymes. As one of the few bacterial exopolygalacturonases, it is able to remove monogalacturonate units from the nonreducing end of polygalacturonate. Detailed characterization of the enzyme showed that PelB is highly thermo-active and thermostable, with a melting temperature of 105 °C and a temperature optimum of 80 °C, the highest described to date for hydrolytic pectinases. PelB showed increasing activity on oligosaccharides with an increasing degree of polymerization. The highest activity was found on the pentamer (1000 U·mg,1). In addition, the affinity increased in conjunction with the length of the oligoGalpA chain. PelB displayed specificity for saturated oligoGalpA and was unable to degrade unsaturated or methyl-esterified oligoGalpA. Analogous to the exopolygalacturonase from Aspergillus tubingensis, it showed low activity with xylogalacturonan. Calculations on the subsite affinity revealed the presence of four subsites and a high affinity for GalpA at subsite +1, which is typical of exo-active enzymes. The physiological role of PelB and the previously characterized exopectate lyase PelA is discussed. [source] Glucose-6-phosphate dehydrogenase from the hyperthermophilic bacterium Thermotoga maritima: expression of the g6pd gene and characterization of an extremely thermophilic enzymeFEMS MICROBIOLOGY LETTERS, Issue 2 2002Thomas Hansen Abstract The gene (open reading frame Tm1155, g6pd) encoding glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) of the hyperthermophilic bacterium Thermotoga maritima was cloned and functionally expressed in Escherichia coli. The purified recombinant enzyme is a homodimer with an apparent molecular mass of 95 kDa composed of 60-kDa subunits. Rate dependence (at 80°C) on glucose-6-phosphate and NADP+ followed Michaelis,Menten kinetics with apparent Km values of 0.15 mM and 0.03 mM, respectively; apparent Vmax values were about 20 U mg,1. The enzyme also reduced NAD+ (apparent Km 12 mM, Vmax 12 U mg,1). The 1000-fold higher catalytic activity (kcat/Km) with NADP+ over NAD+ defines the G6PD as NADP+ specific in vivo. G6PD activity was competitively inhibited by NADPH with a Ki value of 0.11 mM. With a temperature optimum of 92°C the enzyme is the most thermoactive G6PD described. [source] Kinetics of TmHU binding to DNA as observed by optical tweezersMICROSCOPY RESEARCH AND TECHNIQUE, Issue 11 2007Mathias Salomo Abstract The kinetics of binding for the histone-like protein TmHU (from Thermotoga maritima) to DNA is analyzed on a single molecule level by use of optical tweezers. For the reaction rate a pronounced concentration-dependence is found with an "all or nothing"-limit which suggests the cooperative nature of the binding-reaction. By analyzing the statistics of mechanically induced dissociation-events of TmHU from DNA multiple reaction sites are observed to become more likely with increasing TmHU concentration. This is interpreted as a hint for a secondary organizational level of the TmHU/DNA complex. The reaction rate of TmHU binding to DNA is remarkably higher than that of the HU protein from Escherichia coli which will be discussed. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source] Structure of nondiscriminating glutamyl-tRNA synthetase from Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2010Takuhiro Ito Aminoacyl-tRNA synthetases produce aminoacyl-tRNAs from the substrate tRNA and its cognate amino acid with the aid of ATP. Two types of glutamyl-tRNA synthetase (GluRS) have been discovered: discriminating GluRS (D-GluRS) and nondiscriminating GluRS (ND-GluRS). D-GluRS glutamylates tRNAGlu only, while ND-GluRS glutamylates both tRNAGlu and tRNAGln. ND-GluRS produces the intermediate Glu-tRNAGln, which is converted to Gln-tRNAGln by Glu-tRNAGln amidotransferase. Two GluRS homologues from Thermotoga maritima, TM1875 and TM1351, have been biochemically characterized and it has been clarified that only TM1875 functions as an ND-GluRS. Furthermore, the crystal structure of the T. maritima ND-GluRS, TM1875, was determined in complex with a Glu-AMP analogue at 2.0,Å resolution. The T. maritima ND-GluRS contains a characteristic structure in the connective-peptide domain, which is inserted into the catalytic Rossmann-fold domain. The glutamylation ability of tRNAGln by ND-GluRS was measured in the presence of the bacterial Glu-tRNAGln amidotransferase GatCAB. Interestingly, the glutamylation efficiency was not affected even in the presence of excess GatCAB. Therefore, GluRS avoids competition with GatCAB and glutamylates tRNAGln. [source] Complexes of Thermotoga maritimaS -adenosylmethionine decarboxylase provide insights into substrate specificityACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2010Shridhar Bale The polyamines putrescine, spermidine and spermine are ubiquitous aliphatic cations and are essential for cellular growth and differentiation. S -Adenosylmethionine decarboxylase (AdoMetDC) is a critical pyruvoyl-dependent enzyme in the polyamine-biosynthetic pathway. The crystal structures of AdoMetDC from humans and plants and of the AdoMetDC proenzyme from Thermotoga maritima have been obtained previously. Here, the crystal structures of activated T. maritima AdoMetDC (TmAdoMetDC) and of its complexes with S -adenosylmethionine methyl ester and 5,-deoxy-5,-dimethylthioadenosine are reported. The results demonstrate for the first time that TmAdoMetDC autoprocesses without the need for additional factors and that the enzyme contains two complete active sites, both of which use residues from both chains of the homodimer. The complexes provide insights into the substrate specificity and ligand binding of AdoMetDC in prokaryotes. The conservation of the ligand-binding mode and the active-site residues between human and T. maritima AdoMetDC provides insight into the evolution of AdoMetDC. [source] Structures of and interactions between domains of trigger factor from Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2007Erik Martinez-Hackert Trigger factor (TF) is a eubacterial chaperone that associates with ribosomes at the peptide-exit tunnel and also occurs in excess free in the cytosol. TF is a three-domain protein that appears to exist in a dynamic equilibrium of oligomerization states and interdomain conformations. X-ray crystallography and chemical cross-linking were used to study the roles of the N- and C-terminal domains of Thermotoga maritima TF in TF oligomerization and chaperone activity. The structural conservation of both the N- and C-terminal TF domains was unambiguously established. The biochemical and crystallographic data reveal a tendency for these domains to partake in diverse and apparently nonspecific protein,protein interactions. It is found that the T. maritima and Escherichia coli TF surfaces lack evident exposed hydrophobic patches. Taken together, these data suggest that TF chaperones could interact with nascent proteins via hydrophilic surfaces. [source] Crystallization and preliminary X-ray studies of xylanase 10B from Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2003Ihsanawati Xylanases catalyze the hydrolysis of the ,-1,4-glycosidic bonds of xylan, which is the second most abundant component of plant cell walls after cellulose. The recombinant xylanase 10B from Thermotoga maritima MSB8 was prepared and crystallized by the sitting-drop vapour-diffusion method using 40,mM zinc acetate, 20,mM MES buffer pH 6.0 and 3% ethanol. Intensity data were collected to 2.5,Å resolution at beamline BL26B2 of SPring-8. Preliminary X-ray analysis showed that the crystal belongs to space group P21212, with unit-cell parameters a = 77.3, b = 80.6, c = 58.2,Å and one molecule per asymmetric unit. [source] Towards the crystal structure of glycerol dehydrogenase from Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2002Vasundara Srinivasan The NAD+ -dependent glycerol dehydrogenase (EC 1.1.1.6) from the extremely thermophilic bacterium Thermotoga maritima has been crystallized in the presence of glycerol by the hanging-drop vapour-diffusion method using 2-methyl-2,4-pentanediol (MPD) as the precipitating agent. Crystals of the enzyme complexed with NAD+ have also been obtained. The crystals belong to the tetragonal system with space group I422 and unit-cell parameters a = 105.3, c = 134.5,Å. They diffract to a maximum resolution of 1.4,Å using synchrotron radiation (, = 0.838,Å). Crystals of the enzyme,NAD+ complex diffract to 2.5,Å resolution using in-house Cu,K, radiation. [source] Crystallization and preliminary X-ray characterization of a thermostable pectate lyase from Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2002Michael A. McDonough Pectate lyase is an enzyme involved in the degradation of the pectate portion of the primary plant cell wall. A recombinant pectate lyase from Thermotoga maritima where three of the four cysteine residues have been mutated (C132I, C156N, C194L) has been crystallized. Crystals of the same morphology and trigonal space group R3 with similar unit-cell parameters were obtained under two different conditions. The first, 0.3,M (NH4)H2PO4 pH 4.2, gave crystals with a maximum size of 0.4 × 0.2 × 0.2,mm in one week that diffracted to a resolution of 1.87,Å and had unit-cell parameters a = b = 80.6, c = 148.8,Å. The second, 0.1,M sodium acetate, 6%(w/v) PEG 4000 pH 6.5, gave the same size crystals in two weeks that diffracted to a resolution of 2.1,Å and had unit-cell parameters a = b = 80.0, c = 150.1,Å. [source] Crystallization and preliminary X-ray analysis of RecG, a replication-fork reversal helicase from Thermotoga maritima complexed with a three-way DNA junctionACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2001Martin R. Singleton The monomeric 3,-5, helicase RecG from the thermophilic bacterium Thermotoga maritima has been crystallized in complex with a three-way DNA junction, the preferred physiological substrate. The crystals were obtained by hanging-drop vapour diffusion. The crystals belong to space group C2, with unit-cell parameters a = 133.7, b = 144.6, c = 84.0,Å, , = 113.8°. Native data to a resolution of 3.25,Å were collected from crystals flash-cooled to 100,K. [source] Structure of the endonuclease IV homologue from Thermotoga maritima in the presence of active-site divalent metal ionsACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2010Stephen J. Tomanicek The most frequent lesion in DNA is at apurinic/apyrimidinic (AP) sites resulting from DNA-base losses. These AP-site lesions can stall DNA replication and lead to genome instability if left unrepaired. The AP endonucleases are an important class of enzymes that are involved in the repair of AP-site intermediates during damage-general DNA base-excision repair pathways. These enzymes hydrolytically cleave the 5,-phosphodiester bond at an AP site to generate a free 3,-hydroxyl group and a 5,-terminal sugar phosphate using their AP nuclease activity. Specifically, Thermotoga maritima endonuclease IV is a member of the second conserved AP endonuclease family that includes Escherichia coli endonuclease IV, which is the archetype of the AP endonuclease superfamily. In order to more fully characterize the AP endonuclease family of enzymes, two X-ray crystal structures of the T. maritima endonuclease IV homologue were determined in the presence of divalent metal ions bound in the active-site region. These structures of the T. maritima endonuclease IV homologue further revealed the use of the TIM-barrel fold and the trinuclear metal binding site as important highly conserved structural elements that are involved in DNA-binding and AP-site repair processes in the AP endonuclease superfamily. [source] Structure of a putative ,-phosphoglucomutase (TM1254) from Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 12 2009Richard W. Strange The structure of TM1254, a putative ,-phosphoglucomutase from T. maritima, was determined to 1.74,Å resolution in a high-throughput structural genomics programme. Diffraction data were obtained from crystals belonging to space group P22121, with unit-cell parameters a = 48.16, b = 66.70, c = 83.80,Å, and were refined to an R factor of 19.2%. The asymmetric unit contained one protein molecule which is comprised of two domains. Structural homologues were found from protein databases that confirmed a strong resemblance between TM1254 and members of the haloacid dehalogenase (HAD) hydrolase family. [source] Purification, crystallization and preliminary crystallographic analysis of a thermostable endonuclease IV from Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 12 2009Ronny C. Hughes The DNA-repair enzyme endonuclease IV from the thermophilic bacterium Thermotoga maritima MSB8 (reference sequence NC_000853) has been expressed in Escherichia coli and crystallized for X-ray analysis. T. maritima endonuclease IV is a 287-amino-acid protein with 32% sequence identity to E. coli endonuclease IV. The protein was purified to homogeneity and was crystallized using the sitting-drop vapor-diffusion method. The protein crystallized in space group P61, with one biological molecule in the asymmetric unit, corresponding to a Matthews coefficient of 2.39,Å3,Da,1 and 47% solvent content. The unit-cell parameters of the crystals were a = b = 123.2, c = 35.6,Å. Microseeding and further optimization yielded crystals with an X-ray diffraction limit of 2.36,Å. A single 70° data set was collected and processed, resulting in an overall Rmerge and a completeness of 9.5% and 99.3%, respectively. [source] Crystallization and preliminary X-ray diffraction analysis of the truncated cytosolic domain of the iron transporter FeoBACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2009Yaohua Jin FeoB-family proteins are widely distributed in bacteria and archaea and are involved in high-affinity Fe2+ uptake through the plasma membrane. FeoB consists of an N-terminal cytosolic region followed by a C-terminal transmembrane region. The cytosolic region contains small GTPase and GDP dissociation inhibitor-like domains, which serve a regulatory function. The truncated cytosolic region of the iron transporter FeoB from Thermotoga maritima was overexpressed, purified and crystallized. Four native or SeMet crystal forms in a nucleotide-free state or in complex with either GDP or GMPPNP diffracted to resolutions of between 1.5 and 2.1,Å. [source] Structure of a d -tagatose 3-epimerase-related protein from the hyperthermophilic bacterium Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2009Haruhiko Sakuraba The crystal structure of a d -tagatose 3-epimerase-related protein (TM0416p) encoded by the hypothetical open reading frame TM0416 in the genome of the hyperthermophilic bacterium Thermotoga maritima was determined at a resolution of 2.2,Å. The asymmetric unit contained two homologous subunits and a dimer was generated by twofold symmetry. The main-chain coordinates of the enzyme monomer proved to be similar to those of d -tagatose 3-epimerase from Pseudomonas cichorii and d -psicose 3-epimerase from Agrobacterium tumefaciens; however, TM0416p exhibited a unique solvent-accessible substrate-binding pocket that reflected the absence of an ,-helix that covers the active-site cleft in the two aforementioned ketohexose 3-epimerases. In addition, the residues responsible for creating a hydrophobic environment around the substrate in TM0416p differ entirely from those in the other two enzymes. Collectively, these findings suggest that the substrate specificity of TM0416p is likely to differ substantially from those of other d -tagatose 3-epimerase family enzymes. [source] Plant cell calcium-rich environment enhances thermostability of recombinantly produced ,-amylase from the hyperthermophilic bacterium Thermotoga maritimeBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Monica C. Santa-Maria Abstract In the industrial processing of starch for sugar syrup and ethanol production, a liquefaction step is involved where starch is initially solubilized at high temperature and partially hydrolyzed with a thermostable and thermoactive ,-amylase. Most amylases require calcium as a cofactor for their activity and stability, therefore calcium, along with the thermostable enzyme, are typically added to the starch mixture during enzymatic liquefaction, thereby increasing process costs. An attractive alternative would be to produce the enzyme directly in the tissue to be treated. In a proof of concept study, tobacco cell cultures were used as model system to test in planta production of a hyperthermophilic ,-amylase from Thermotoga maritima. While comparable biochemical properties to recombinant production in Escherichia coli were observed, thermostability of the plant-produced ,-amylase benefited significantly from high intrinsic calcium levels in the tobacco cells. The plant-made enzyme retained 85% of its initial activity after 3,h incubation at 100°C, whereas the E. coli -produced enzyme was completely inactivated after 30,min under the same conditions. The addition of Ca2+ or plant cell extracts from tobacco and sweetpotato to the E. coli -produced enzyme resulted in a similar stabilization, demonstrating the importance of a calcium-rich environment for thermostability, as well as the advantage of producing this enzyme directly in plant cells where calcium is readily available. Biotechnol. Bioeng. 2009; 104: 947,956. © 2009 Wiley Periodicals, Inc. [source] Purification, crystallization and preliminary X-ray diffraction analysis of the putative ABC transporter ATP-binding protein from Thermotoga maritimaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2008Abdul S. Ethayathulla Adenosine triphosphate (ATP) binding cassette transporters (ABC transporters) are ATP hydrolysis-dependent transmembrane transporters. Here, the overproduction, purification and crystallization of the putative ABC transporter ATP-binding protein TM0222 from Thermotoga maritima are reported. The protein was crystallized in the hexagonal space group P6422, with unit-cell parameters a = b = 148.49, c = 106.96,Å, , = 120.0°. Assuming the presence of two molecules in the asymmetric unit, the calculated VM is 2.84,Å3,Da,1, which corresponds to a solvent content of 56.6%. A three-wavelength MAD data set was collected to 2.3,Å resolution from SeMet-substituted TM0222 crystals. Data sets were collected on the BL38B1 beamline at SPring-8, Japan. [source] Direct measurement of the kinetics of CBM9 fusion-tag bioprocessing using luminescence resonance energy transferBIOTECHNOLOGY PROGRESS, Issue 3 2009Mojgan Kavoosi Abstract The economics of affinity-tagging technologies, particularly at preparative scales, depends in part on the cost and efficiency of the bioprocessing step used to remove the affinity tag and obtain the final purified product (Lowe et al., J Biochem Biophys Methods. 2001;49:561,574). When CBM9, the family 9 cellulose binding module from Thermotoga maritima, serves as the affinity tag, the overall efficiency of tag removal is a function of the choice of processing enzyme and the local structure of the cleavage site, most notably the linker sequence flanking the bioprocessing recognition site on the tag side. A novel spectroscopic method is reported and used to rapidly and accurately measure CBM9 fusion-tag bioprocessing kinetics and their dependence on the choice of linker sequence. The assay monitors energy transfer between a lanthanide-based donor bound to the CBM9 tag and an acceptor fluorophore presented on the target protein or peptide. Enzyme-catalyzed cleavage of the fusion tag terminates this resonance energy transfer, resulting in a change in fluorescence intensity that can be monitored to quantify substrate concentration over time. The assay is simple, fast and accurate, providing kcat/KM values that contain standard errors of less than 3%. As a result, both substantial and subtle differences in bioprocessing kinetics can be measured and used to guide bioproduct design. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Crystallization and preliminary X-ray diffraction analysis of the cytosolic domain of a cation diffusion facilitator family proteinACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2007Motoyuki Hattori The cation diffusion facilitator (CDF) family proteins are ubiquitously distributed in the three domains of life and transport metals such as zinc and various heavy metals. Prokaryotic CDF proteins consists of an N-terminal putative six-transmembrane domain followed by a C-terminal cytosolic domain. The cytosolic domain of the CDF-family protein from Thermotoga maritima has been overexpressed, purified and crystallized. The selenomethionine-substituted crystals diffracted X-rays to 2.5,Å resolution using synchrotron radiation, belonged to space group R32, with unit-cell parameters a = b = 97.7, c = 83.4,Å, and are expected to contain one molecule in each asymmetric unit. [source] The Role of Arginine 28 in Catalysis by Dihydrofolate Reductase from the Hyperthermophile Thermotoga maritimaCHEMBIOCHEM, Issue 16 2009E. Joel Loveridge Dr. Get a grip: Dihydrofolate reductase from Thermotoga maritima (TmDHFR) is unusual in that it has an arginine residue within its active site (ringed residue). Here, we address the role of this residue in catalysis. We find no evidence that Arg28 compromises catalysis in TmDHFR by preventing protonation of the substrate or that it acts as an acid to protonate the substrate. Instead, it appears that this residue plays an important role in binding the substrate tightly to ensure its thermal stability. [source] Molecular Basis for ,-Glucosidase Inhibition by Ring-Modified Calystegine AnaloguesCHEMBIOCHEM, Issue 16 2008Matilde Aguilar Neutral calystegine B2analogues, such as the 1-deoxy-6-oxa- N -(N, -octyl)thiocarbamoyl derivative, proved to be more potent ,-glucosidase inhibitors than the natural alkaloid. Structural studies of the complex with a clan GH-A ,-glucosidase from Thermotoga maritima showed a binding mode markedly different from that of the parent compound. [source] A Robust Protein Host for Anchoring Chelating Ligands and OrganocatalystsCHEMBIOCHEM, Issue 4 2008Manfred T. Reetz Prof. Dr. Abstract In order to put the previously proposed concept of directed evolution of hybrid catalysts (proteins that harbor synthetic transition-metal catalysts or organocatalysts) into practice, several prerequisites must be met. The availability of a robust host protein that can be expressed in sufficiently large amounts, and that can be purified in a simple manner is crucial. The thermostable enzyme tHisF from Thermotoga maritima, which constitutes the synthase subunit of a bi-enzyme complex that is instrumental in the biosynthesis of histidine, fulfills these requirements. In the present study, fermentation has been miniaturized and parallelized, as has purification of the protein by simple heat treatment. Several mutants with strategically placed cysteines for subsequent bioconjugation have been produced. One of the tHisF mutants, Cys9Ala/Asp11Cys, was subjected to bioconjugation by the introduction of a variety of ligands for potential metal ligation, of a ligand/metal moiety, and of several organocatalytic entities that comprise a flavin or thiazolium salts. Characterization by mass spectrometry and tryptic digestion was achieved. As a result of this study, a platform for performing future directed evolution of these hybrid catalysts is now available. [source] Dissection of Conformationally Restricted Inhibitors Binding to a ,-GlucosidaseCHEMBIOCHEM, Issue 5 2006Tracey M. Gloster Dr. Glycosidase inhibition, important in the quest for highly potent and specific drugs, can be achieved by mimicking the oxocarbenium ion-like transition-state species that form during the catalytic mechanism. Castanospermine (left) and calystegine B2 (right) are potent inhibitors that are conformationally restricted by the inclusion of ethylene linkers. Their binding to a ,-glucosidase from Thermotoga maritima has been studied by structural, kinetic and thermodynamic methods. Although both compounds inhibit with a similar potency, castanospermine derives the majority of it energetic contribution from enthalpy whereas calystegine B2 binding is more entropically driven. [source] Complexes of Thermotoga maritimaS -adenosylmethionine decarboxylase provide insights into substrate specificityACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2010Shridhar Bale The polyamines putrescine, spermidine and spermine are ubiquitous aliphatic cations and are essential for cellular growth and differentiation. S -Adenosylmethionine decarboxylase (AdoMetDC) is a critical pyruvoyl-dependent enzyme in the polyamine-biosynthetic pathway. The crystal structures of AdoMetDC from humans and plants and of the AdoMetDC proenzyme from Thermotoga maritima have been obtained previously. Here, the crystal structures of activated T. maritima AdoMetDC (TmAdoMetDC) and of its complexes with S -adenosylmethionine methyl ester and 5,-deoxy-5,-dimethylthioadenosine are reported. The results demonstrate for the first time that TmAdoMetDC autoprocesses without the need for additional factors and that the enzyme contains two complete active sites, both of which use residues from both chains of the homodimer. The complexes provide insights into the substrate specificity and ligand binding of AdoMetDC in prokaryotes. The conservation of the ligand-binding mode and the active-site residues between human and T. maritima AdoMetDC provides insight into the evolution of AdoMetDC. [source] | |||||||||||||