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Acta Crystallographica. Section D, Structural Biology

Marina Plaza-Garrido, M Carmen Salinas-Garcia, Ana Camara-Artigas
The structure of orthorhombic lysozyme has been obtained at 298 K and pH 4.5 using sodium chloride as the precipitant and in the presence of sodium phosphate at a concentration as low as 5 mM. Crystals belonging to space group P21 21 21 (unit-cell parameters a = 30, b = 56, c = 73 Å, α = β = γ = 90.00°) diffracted to a resolution higher than 1 Å, and the high quality of these crystals permitted the identification of a phosphate ion bound to Arg14 and His15. The binding of this ion produces long-range conformational changes affecting the loop containing Ser60-Asn74...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Timothy J Tyree, Ritwik Dan, Robert E Thorne
The glass-phase densities at T = 77 K of aqueous solutions of the common cryoprotective agents (CPAs) methanol, ethanol, 2-propanol, glycerol, 2-methyl-2,4-pentanediol (MPD), ethylene glycol, polyethylene glycol 200 and polypropylene glycol 425 were measured as a function of CPA concentration. Individual drops with volumes as small as ∼65 pl were rapidly cooled to achieve the glass phase, and their densities at T = 77 K were determined by cryoflotation. These densities were used to determine the glass-phase electron density of each solution and its volume thermal contraction between room temperature and 77 K...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Christian Roth, Olga V Moroz, Antonio Ariza, Lars K Skov, Keiichi Ayabe, Gideon J Davies, Keith S Wilson
Glucoamylases are one of the most important classes of enzymes in the industrial degradation of starch biomass. They consist of a catalytic domain and a carbohydrate-binding domain (CBM), with the latter being important for the interaction with the polymeric substrate. Whereas the catalytic mechanisms and structures of the individual domains are well known, the spatial arrangement of the domains with respect to each other and its influence on activity are not fully understood. Here, the structures of three industrially used fungal glucoamylases, two of which are full length, have been crystallized and determined...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Arne C Rufer, Eric Kusznir, Dominique Burger, Martine Stihle, Armin Ruf, Markus G Rudolph
Doublecortin, a microtubule-associated protein that is only produced during neurogenesis, cooperatively binds to microtubules and stimulates microtubule polymerization and cross-linking by unknown mechanisms. A domain swap is observed in the crystal structure of the C-terminal domain of doublecortin. As determined by analytical ultracentrifugation, an open conformation is also present in solution. At higher concentrations, higher-order oligomers of the domain are formed. The domain swap and additional interfaces observed in the crystal lattice can explain the formation of doublecortin tetramers or multimers, in line with the analytical ultracentrifugation data...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Keitaro Yamashita, Kunio Hirata, Masaki Yamamoto
In protein microcrystallography, radiation damage often hampers complete and high-resolution data collection from a single crystal, even under cryogenic conditions. One promising solution is to collect small wedges of data (5-10°) separately from multiple crystals. The data from these crystals can then be merged into a complete reflection-intensity set. However, data processing of multiple small-wedge data sets is challenging. Here, a new open-source data-processing pipeline, KAMO, which utilizes existing programs, including the XDS and CCP4 packages, has been developed to automate whole data-processing tasks in the case of multiple small-wedge data sets...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Olof Svensson, Maciej Gilski, Didier Nurizzo, Matthew W Bowler
Macromolecular crystallography is now a mature and widely used technique that is essential in the understanding of biology and medicine. Increases in computing power combined with robotics have not only enabled large numbers of samples to be screened and characterized but have also enabled better decisions to be taken on data collection itself. This led to the development of MASSIF-1 at the ESRF, the first beamline in the world to run fully automatically while making intelligent decisions taking user requirements into account...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Christian Kubitza, Annette Faust, Miriam Gutt, Luzia Gäth, Dietrich Ober, Axel J Scheidig
The high-resolution crystal structure of the flavin-dependent monooxygenase (FMO) from the African locust Zonocerus variegatus is presented and the kinetics of structure-based protein variants are discussed. Z. variegatus expresses three flavin-dependent monooxygenase (ZvFMO) isoforms which contribute to a counterstrategy against pyrrolizidine alkaloids (PAs). PAs are protoxic compounds produced by some angiosperm lineages as a chemical defence against herbivores. N-Oxygenation of PAs and the accumulation of PA N-oxides within their haemolymph result in two evolutionary advantages for these insects: (i) they circumvent the defence mechanism of their food plants and (ii) they can use PA N-oxides to protect themselves against predators, which cannot cope with the toxic PAs...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Michael C Thompson, Duilio Cascio, Todd O Yeates
Real macromolecular crystals can be non-ideal in a myriad of ways. This often creates challenges for structure determination, while also offering opportunities for greater insight into the crystalline state and the dynamic behavior of macromolecules. To evaluate whether different parts of a single crystal of a dynamic protein, EutL, might be informative about crystal and protein polymorphism, a microfocus X-ray synchrotron beam was used to collect a series of 18 separate data sets from non-overlapping regions of the same crystal specimen...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Richard J Gildea, Graeme Winter
Combining X-ray diffraction data from multiple samples requires determination of the symmetry and resolution of any indexing ambiguity. For the partial data sets typical of in situ room-temperature experiments, determination of the correct symmetry is often not straightforward. The potential for indexing ambiguity in polar space groups is also an issue, although methods to resolve this are available if the true symmetry is known. Here, a method is presented to simultaneously resolve the determination of the Patterson symmetry and the indexing ambiguity for partial data sets...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Andrew J Thompson, Richard J Spears, Yanping Zhu, Michael D L Suits, Spencer J Williams, Harry J Gilbert, Gideon J Davies
A dominant human gut microbe, the well studied symbiont Bacteroides thetaiotaomicron (Bt), is a glyco-specialist that harbors a large repertoire of genes devoted to carbohydrate processing. Despite strong similarities among them, many of the encoded enzymes have evolved distinct substrate specificities, and through the clustering of cognate genes within operons termed polysaccharide-utilization loci (PULs) enable the fulfilment of complex biological roles. Structural analyses of two glycoside hydrolase family 92 α-mannosidases, BT3130 and BT3965, together with mechanistically relevant complexes at 1...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Tanja Küssau, Marion Flipo, Niel Van Wyk, Albertus Viljoen, Vincent Olieric, Laurent Kremer, Mickaël Blaise
In mycobacteria, the ketoacyl-acyl carrier protein (ACP) reductase MabA (designated FabG in other bacteria) catalyzes the NADPH-dependent reduction of β-ketoacyl-ACP substrates to β-hydroxyacyl-ACP products. This first reductive step in the fatty-acid biosynthesis elongation cycle is essential for bacteria, which makes MabA/FabG an interesting drug target. To date, however, very few molecules targeting FabG have been discovered and MabA remains the only enzyme of the mycobacterial type II fatty-acid synthase that lacks specific inhibitors...
May 1, 2018: Acta Crystallographica. Section D, Structural Biology
Schuyler Lee, Chao Wang, Haolin Liu, Jian Xiong, Renee Jiji, Xia Hong, Xiaoxue Yan, Zhangguo Chen, Michal Hammel, Yang Wang, Shaodong Dai, Jing Wang, Chengyu Jiang, Gongyi Zhang
The paper by Lee et al. [(2017). Acta Cryst. D73, 955-969] is withdrawn.
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
Michail N Isupov, Ewald Schröder, Robert P Gibson, Jean Beecher, Giuliana Donadio, Vahid Saneei, Stephlina A Dcunha, Emma J McGhie, Christopher Sayer, Colin F Davenport, Peter C K Lau, Yoshie Hasegawa, Hiroaki Iwaki, Maria Kadow, Kathleen Balke, Uwe T Bornscheuer, Gleb Bourenkov, Jennifer A Littlechild
A statement is amended in the article by Isupov et al. [(2015). Acta Cryst. D71, 2344-2353].
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
Nicolas Foos, Carolin Seuring, Robin Schubert, Anja Burkhardt, Olof Svensson, Alke Meents, Henry N Chapman, Max H Nanao
Specific radiation damage can be used to determine phases de novo from macromolecular crystals. This method is known as radiation-damage-induced phasing (RIP). One limitation of the method is that the dose of individual data sets must be minimized, which in turn leads to data sets with low multiplicity. A solution to this problem is to use data from multiple crystals. However, the resulting signal can be degraded by a lack of isomorphism between crystals. Here, it is shown that serial synchrotron crystallography in combination with selective merging of data sets can be used to determine high-quality phases for insulin and thaumatin, and that the increased multiplicity can greatly enhance the success rate of the experiment...
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
Igor Melnikov, Olof Svensson, Gleb Bourenkov, Gordon Leonard, Alexander Popov
In macromolecular crystallography, mesh (raster) scans are carried out either as part of X-ray-based crystal-centring routines or to identify positions on the sample holder from which diffraction images can be collected. Here, the methods used in MeshBest, software which automatically analyses diffraction images collected during a mesh scan and produces a two-dimensional crystal map showing estimates of the dimensions, centre positions and diffraction qualities of each crystal contained in the mesh area, are presented...
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
Santosh Kumar Chaudhary, Jeyaraman Jeyakanthan, Kanagaraj Sekar
Thymidylate kinase is an important enzyme in DNA synthesis. It catalyzes the conversion of thymidine monophosphate to thymidine diphosphate, with ATP as the preferred phosphoryl donor, in the presence of Mg2+ . In this study, the dynamics of the active site and the communication paths between the substrates, ATP and TMP, are reported for thymidylate kinase from Thermus thermophilus. Conformational changes upon ligand binding and the path for communication between the substrates and the protein are important in understanding the catalytic mechanism of the enzyme...
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
C E Alvarez, F Trajtenberg, N Larrieux, M Saigo, A Golic, C S Andreo, S A Hogenhout, M A Mussi, M F Drincovich, A Buschiazzo
Phytoplasmas are wall-less phytopathogenic bacteria that produce devastating effects in a wide variety of plants. Reductive evolution has shaped their genome, with the loss of many genes, limiting their metabolic capacities. Owing to the high concentration of C4 compounds in plants, and the presence of malic enzyme (ME) in all phytoplasma genomes so far sequenced, the oxidative decarboxylation of L-malate might represent an adaptation to generate energy. Aster yellows witches'-broom (Candidatus Phytoplasma) ME (AYWB-ME) is one of the smallest of all characterized MEs, yet retains full enzymatic activity...
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
Nina M Wolf, Hiten J Gutka, Farahnaz Movahedzadeh, Celerino Abad-Zapatero
The crystal structures of native class II fructose-1,6-bisphosphatase (FBPaseII) from Mycobacterium tuberculosis at 2.6 Å resolution and two active-site protein variants are presented. The variants were complexed with the reaction product fructose 6-phosphate (F6P). The Thr84Ala mutant is inactive, while the Thr84Ser mutant has a lower catalytic activity. The structures reveal the presence of a 222 tetramer, similar to those described for fructose-1,6/sedoheptulose-1,7-bisphosphatase from Synechocystis (strain 6803) as well as the equivalent enzyme from Thermosynechococcus elongatus...
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
Renate Gessmann, Hans Brückner, Albrecht Berg, Kyriacos Petratos
The crystal structure of the natural nonapeptide antibiotic helioferin has been determined and refined to 0.9 Å resolution. Helioferin consists of helioferin A and B, which contain 2-(2'-aminopropyl)aminoethanol (Apae) and 2-[(2'-aminopropyl)methylamino]ethanol (Amae) at their respective alkanolamine termini. In addition, helioferin contains the unusual amino-acid residues α-aminoisobutyric acid (Aib) and (2S,4S,6S)-2-amino-6-hydroxy-4-methyl-8-oxodecanoic acid (Ahmod). The amino-terminus is capped with 2-methyl-n-1-octanoic acid (M8a)...
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
Jingxu Guo, Alun R Coker, Steve P Wood, Jonathan B Cooper, Ronan M Keegan, Nasir Ahmad, Majida Atta Muhammad, Naeem Rashid, Muhummad Akhtar
Pullulan-hydrolysing enzymes, more commonly known as debranching enzymes for starch and other polysaccharides, are of great interest and have been widely used in the starch-saccharification industry. Type III pullulan hydrolase from Thermococcus kodakarensis (TK-PUL) possesses both pullulanase and α-amylase activities. Until now, only two enzymes in this class, which are capable of hydrolysing both α-1,4- and α-1,6-glycosidic bonds in pullulan to produce a mixture of maltose, panose and maltotriose, have been described...
April 1, 2018: Acta Crystallographica. Section D, Structural Biology
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