scholarly journals How cyanophage S-2L rejects adenine and incorporates 2-aminoadenine to saturate hydrogen bonding in its DNA

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dariusz Czernecki ◽  
Pierre Legrand ◽  
Mustafa Tekpinar ◽  
Sandrine Rosario ◽  
Pierre-Alexandre Kaminski ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Active Site ◽  
Metal Ion ◽  
Restriction Endonucleases ◽  
Structural Element

AbstractBacteriophages have long been known to use modified bases in their DNA to prevent cleavage by the host’s restriction endonucleases. Among them, cyanophage S-2L is unique because its genome has all its adenines (A) systematically replaced by 2-aminoadenines (Z). Here, we identify a member of the PrimPol family as the sole possible polymerase of S-2L and we find it can incorporate both A and Z in front of a T. Its crystal structure at 1.5 Å resolution confirms that there is no structural element in the active site that could lead to the rejection of A in front of T. To resolve this contradiction, we show that a nearby gene is a triphosphohydolase specific of dATP (DatZ), that leaves intact all other dNTPs, including dZTP. This explains the absence of A in S-2L genome. Crystal structures of DatZ with various ligands, including one at sub-angstrom resolution, allow to describe its mechanism as a typical two-metal-ion mechanism and to set the stage for its engineering.

Crystal structure of dimeric Synechococcus spermidine synthase with bound polyamine substrate and product

2019 ◽  
Vol 476 (6) ◽  
pp. 1009-1020 ◽  
Author(s):  
Gabriela Guédez ◽  
Apiradee Pothipongsa ◽  
Saija Sirén ◽  
Arto Liljeblad ◽  
Saowarath Jantaro ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Catalytic Reaction ◽  
Active Site ◽  
Enzymatic Reaction ◽  
Spermidine Synthase ◽  
Structural Element ◽  
Expression Host ◽  
Gate Keeping

AbstractSpermidine is a ubiquitous polyamine synthesized by spermidine synthase (SPDS) from the substrates, putrescine and decarboxylated S-adenosylmethionine (dcAdoMet). SPDS is generally active as homodimer, but higher oligomerization states have been reported in SPDS from thermophiles, which are less specific to putrescine as the aminoacceptor substrate. Several crystal structures of SPDS have been solved with and without bound substrates and/or products as well as inhibitors. Here, we determined the crystal structure of SPDS from the cyanobacterium Synechococcus (SySPDS) that is a homodimer, which we also observed in solution. Unlike crystal structures reported for bacterial and eukaryotic SPDS with bound ligands, SySPDS structure has not only bound putrescine substrate taken from the expression host, but also spermidine product most probably as a result of an enzymatic reaction. Hence, to the best of our knowledge, this is the first structure reported with both amino ligands in the same structure. Interestingly, the gate-keeping loop is disordered in the putrescine-bound monomer while it is stabilized in the spermidine-bound monomer of the SySPDS dimer. This confirms the gate-keeping loop as the key structural element that prepares the active site upon binding of dcAdoMet for the catalytic reaction of the amine donor and putrescine.

Complexes of Copper, Silver, and Gold with Urea Homologues. Crystal Structures of [{µ2-SeC(NH2)2} Ag{SeC(NH2)2}2]22+2Cl- • 4 DMF and [Ph3PAu{SC(NHMe)2}]+Cl- • SC(NHMe)2

1994 ◽  
Vol 49 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Wolfgang Eikens ◽  
Peter G. Jones ◽  
Jürgen Lautner ◽  
Carsten Thöne
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Dinuclear Complex ◽  
Selenium Atom

Abstract The title compounds were prepared from chloro(organophosphine)metal(I) complexes and the urea homologues SeC(NH2)2 and SC(NHMe)2 in good yields. Recrystallization of [Ph3,PAg{SeC(NH2)2}]+Cl- from DMF/CH2Cl2 leads in low yield to the dinuclear complex [{µ2-SeC(NH2)2}Ag{SeC(NH2)2}2]22+2Cl- • 4DMF. The crystal structure reveals short Ag-Ag contacts and unexpectedly acute angles at the bridging selenium atom. The crystal structure of [Ph3PAu{SC(NHMe)2}]+Cl- • SC(NHMe)2 shows short N•••Cl and N•••S contacts that probably correspond to hydrogen bonding.

scholarly journals Crystal structures of murine norovirus-1 RNA-dependent RNA polymerase

2011 ◽  
Vol 92 (7) ◽  
pp. 1607-1616 ◽  
Author(s):  
Ji-Hye Lee ◽  
Intekhab Alam ◽  
Kang Rok Han ◽  
Sunyoung Cho ◽  
Sungho Shin ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Crystal Structures ◽  
Active Site ◽  
Metal Ion ◽  
Health Concern ◽  
Murine Norovirus ◽  
Active Site Residues ◽  
Rna Dependent Rna Polymerase ◽  
Close Proximity ◽  
Functional Features

Norovirus is one of the leading agents of gastroenteritis and is a major public health concern. In this study, the crystal structures of recombinant RNA-dependent RNA polymerase (RdRp) from murine norovirus-1 (MNV-1) and its complex with 5-fluorouracil (5FU) were determined at 2.5 Å resolution. Crystals with C2 symmetry revealed a dimer with half a dimer in the asymmetrical unit, and the protein exists predominantly as a monomer in solution, in equilibrium with a smaller population of dimers, trimers and hexamers. MNV-1 RdRp exhibited polymerization activity with a right-hand fold typical of polynucleotide polymerases. The metal ion modelled in close proximity to the active site was found to be coordinated tetrahedrally to the carboxyl groups of aspartate clusters. The orientation of 5FU observed in three molecules in the asymmetrical unit was found to be slightly different, but it was stabilized by a network of favourable interactions with the conserved active-site residues Arg185, Asp245, Asp346, Asp347 and Arg395. The information gained on the structural and functional features of MNV-1 RdRp will be helpful in understanding replication of norovirus and in designing novel therapeutic agents against this important pathogen.

scholarly journals A trapped human PPM1A–phosphopeptide complex reveals structural features critical for regulation of PPM protein phosphatase activity

2018 ◽  
Vol 293 (21) ◽  
pp. 7993-8008 ◽  
Author(s):  
Subrata Debnath ◽  
Dalibor Kosek ◽  
Harichandra D. Tagad ◽  
Stewart R. Durell ◽  
Daniel H. Appella ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Metal Ions ◽  
Active Site ◽  
Metal Binding ◽  
Metal Ion ◽  
Catalytic Domain ◽  
Protein Phosphatases ◽  
Random Order ◽  
Structural Features

Metal-dependent protein phosphatases (PPM) are evolutionarily unrelated to other serine/threonine protein phosphatases and are characterized by their requirement for supplementation with millimolar concentrations of Mg2+ or Mn2+ ions for activity in vitro. The crystal structure of human PPM1A (also known as PP2Cα), the first PPM structure determined, displays two tightly bound Mn2+ ions in the active site and a small subdomain, termed the Flap, located adjacent to the active site. Some recent crystal structures of bacterial or plant PPM phosphatases have disclosed two tightly bound metal ions and an additional third metal ion in the active site. Here, the crystal structure of the catalytic domain of human PPM1A, PPM1Acat, complexed with a cyclic phosphopeptide, c(MpSIpYVA), a cyclized variant of the activation loop of p38 MAPK (a physiological substrate of PPM1A), revealed three metal ions in the active site. The PPM1Acat D146E–c(MpSIpYVA) complex confirmed the presence of the anticipated third metal ion in the active site of metazoan PPM phosphatases. Biophysical and computational methods suggested that complex formation results in a slightly more compact solution conformation through reduced conformational flexibility of the Flap subdomain. We also observed that the position of the substrate in the active site allows solvent access to the labile third metal-binding site. Enzyme kinetics of PPM1Acat toward a phosphopeptide substrate supported a random-order, bi-substrate mechanism, with substantial interaction between the bound substrate and the labile metal ion. This work illuminates the structural and thermodynamic basis of an innate mechanism regulating the activity of PPM phosphatases.

scholarly journals Crystal structures of two monomeric triosephosphate isomerase variants identifiedviaa directed-evolution protocol selecting forL-arabinose isomerase activity

2016 ◽  
Vol 72 (6) ◽  
pp. 490-499
Author(s):  
Mirja Krause ◽  
Tiila-Riikka Kiema ◽  
Peter Neubauer ◽  
Rik K. Wierenga
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Directed Evolution ◽  
Crystal Structures ◽  
Active Site ◽  
Triosephosphate Isomerase ◽  
Point Mutations ◽  
Van Der Waals Interactions ◽  
Side Chain ◽  
Arabinose Isomerase

The crystal structures are described of two variants of A-TIM: Ma18 (2.7 Å resolution) and Ma21 (1.55 Å resolution). A-TIM is a monomeric loop-deletion variant of triosephosphate isomerase (TIM) which has lost the TIM catalytic properties. Ma18 and Ma21 were identified after extensive directed-evolution selection experiments using anEscherichia coliL-arabinose isomerase knockout strain expressing a randomly mutated A-TIM gene. These variants facilitate better growth of theEscherichia coliselection strain in medium supplemented with 40 mML-arabinose. Ma18 and Ma21 differ from A-TIM by four and one point mutations, respectively. Ma18 and Ma21 are more stable proteins than A-TIM, as judged from CD melting experiments. Like A-TIM, both proteins are monomeric in solution. In the Ma18 crystal structure loop 6 is open and in the Ma21 crystal structure loop 6 is closed, being stabilized by a bound glycolate molecule. The crystal structures show only small differences in the active site compared with A-TIM. In the case of Ma21 it is observed that the point mutation (Q65L) contributes to small structural rearrangements near Asn11 of loop 1, which correlate with different ligand-binding properties such as a loss of citrate binding in the active site. The Ma21 structure also shows that its Leu65 side chain is involved in van der Waals interactions with neighbouring hydrophobic side-chain moieties, correlating with its increased stability. The experimental data suggest that the increased stability and solubility properties of Ma21 and Ma18 compared with A-TIM cause better growth of the selection strain when coexpressing Ma21 and Ma18 instead of A-TIM.

scholarly journals Crystal structures of chlorido[dihydroxybis(1-iminoethoxy)]arsanido-κ3 N,As,N′]platinum(II) and of a polymorph of chlorido[dihydroxybis(1-iminopropoxy)arsanido-κ3 N,As,N′]platinum(II)

2020 ◽  
Vol 76 (2) ◽  
pp. 180-185
Author(s):  
Nina R. Marogoa ◽  
D.V. Kama ◽  
Hendrik G. Visser ◽  
M. Schutte-Smith
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Three Dimensional ◽  
Donor Ligands ◽  
Intermolecular Hydrogen Bonding ◽  
Π Interactions ◽  
Hydrogen Bonding Interactions ◽  
Oxygen Donor ◽  
Dimensional Network

Each central platinum(II) atom in the crystal structures of chlorido[dihydroxybis(1-iminoethoxy)arsanido-κ3 N,As,N′]platinum(II), [Pt(C4H10AsN2O4)Cl] (1), and of chlorido[dihydroxybis(1-iminopropoxy)arsanido-κ3 N,As,N′]platinum(II), [Pt(C6H14AsN2O4)Cl] (2), is coordinated by two nitrogen donor atoms, a chlorido ligand and to arsenic, which, in turn, is coordinated by two oxygen donor ligands, two hydroxyl ligands and the platinum(II) atom. The square-planar and trigonal–bipyramidal coordination environments around platinum and arsenic, respectively, are significantly distorted with the largest outliers being 173.90 (13) and 106.98 (14)° for platinum and arsenic in (1), and 173.20 (14)° and 94.20 (9)° for (2), respectively. One intramolecular and four classical intermolecular hydrogen-bonding interactions are observed in the crystal structure of (1), which give rise to an infinite three-dimensional network. A similar situation (one intramolecular and four classical intermolecular hydrogen-bonding interactions) is observed in the crystal structure of (2). Various π-interactions are present in (1) between the platinum(II) atom and the centroid of one of the five-membered rings formed by Pt, As, C, N, O with a distance of 3.7225 (7) Å, and between the centroids of five-membered (Pt, As, C, N, O) rings of neighbouring molecules with distances of 3.7456 (4) and 3.7960 (6) Å. Likewise, weak π-interactions are observed in (2) between the platinum(II) atom and the centroid of one of the five-membered rings formed by Pt, As, C, N, O with a distance of 3.8213 (2) Å, as well as between the Cl atom and the centroid of a symmetry-related five-membered ring with a distance of 3.8252 (12) Å. Differences between (2) and the reported polymorph [Miodragović et al. (2013). Angew. Chem. Int. Ed. 52, 10749–10752] are discussed.

The crystal structure of α-D-glucosamine hydrochloride and hydrobromide

1965 ◽  
Vol 285 (1403) ◽  
pp. 470-479 ◽  
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Lower Energy ◽  
Pyranose Ring ◽  
Glucosamine Hydrochloride ◽  
Ionic Hydrogen Bonding ◽  
Original Experimental Data

The crystal structures of α-D-glucosamine hydrochloride and hydrobromide have been redetermined and refined from the original experimental data. The pyranose ring of the sugar molecule has the expected normal Sachse trans configuration with the lower energy conformation 1 a 2 e 3 e 4 e 5 e . The most interesting feature of these new results is now the inter-ionic hydrogen-bonding, which is dominated by the co-ordination about the NH 3 + groups and the anions.

Structural Studies of Complexes of Tridentate Terimine Systems. Crystal Structure of Bis(2,2′:6′,2′′-terpyridine)ruthenium(II) Perchlorate Hydrate, Bis(2,2′:6′,2′′-terpyridine)- osmium(II) Perchlorate Hemihydrate and Bis((1,10-phenanthrolin-2-yl)(pyridin-2-yl)amine)iron(II) Tetrafluoroborate Dihydrate

1998 ◽  
Vol 51 (12) ◽  
pp. 1131 ◽  
Author(s):  
Donald C. Craig ◽  
Marcia L. Scudder ◽  
Wendy-Anne McHale ◽  
Harold A. Goodwin
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Metal Ion ◽  
Chelate Ring ◽  
Monoclinic Space Group ◽  
Structural Studies ◽  
Triclinic Space Group ◽  
Space Group ◽  
Membered Chelate Ring ◽  
Group I

The crystal structures of bis(2,2′:6′,2″-terpyridine)ruthenium(II) perchlorate hydrate, bis(2,2′:6′,2″- terpyridine)osmium(II) perchlorate hemihydrate and bis((1,10-phenanthrolin-2-yl)(pyridin-2-yl)- amine)iron(II) tetrafluoroborate dihydrate are described. In the terpyridine complexes the ruthenium-nitrogen distances and the corresponding osmium-nitrogen distances are not significantly different. In both complexes the ligand geometry and the metal ion environment show the distortions usual for bis(terpyridine) systems. Distortions are less marked in the bis((1,10-phenanthrolin-2-yl)(pyridin-2-yl)amine)iron(II) cation in which each tridentate unit forms one five-membered and one six-membered chelate ring. [Ru(trpy)2] [ClO4]2.(H2O)1.1: tetragonal, space group I 41/a, a, b 12·527(2), c 40·202(11) Å, Z 8. [Os(trpy)2] [ClO4]2.(H2O)0·5: monoclinic, space group P 21/n, a 8·842(3), b 8·861(1), c 39·22(2) Å, β93·89(2)°, Z 4. [Fe(phpyam)2] [BF4]2.(H2O)2: triclinic, space group P -1, a 12·43(1), b 12·45(1), c 13·35(1) Å, α 62·70(10), β 78·55(8), γ 72·46(9)°, Z 2.

Crystal structures of cefdinir, C14H13N5O5S2, and cefdinir sesquihydrate C14H13N5O5S2(H2O)1.5

2019 ◽  
Vol 34 (3) ◽  
pp. 267-278
Author(s):  
Austin M. Wheatley ◽  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
Powder Diffraction File ◽  
Space Group ◽  
X Ray ◽  
Additional Hydrogen

The crystal structures of cefdinir and cefdinir sesquihydrate have been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Cefdinir crystallizes in space group P21 (#4) with a = 5.35652(4), b = 19.85676(10), c = 7.57928(5) Å, β = 97.050(1) °, V = 800.061(6) Å3, and Z = 2. Cefdinir sesquihydrate crystallizes in space group C2 (#5) with a = 23.98775(20), b = 5.01646(3), c = 15.92016(12) Å, β = 109.4470(8) °, V = 1806.438(16) Å3, and Z = 4. The cefdinir molecules in the anhydrous crystal structure and sesquihydrate have very different conformations. The two conformations are similar in energy. The hydrogen bonding patterns are very different in the two structures, and the sesquihydrate is more stable than expected from the sum of the energies of cefdinir and cefdinir sesquihydrate, the result of additional hydrogen bonding. The powder patterns are included in the Powder Diffraction File™ as entries 00-066-1604 (cefdinir) and 00-066-1605 (cefdinir sesquihydrate).

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