scholarly journals Insights into the structural basis of the pH-dependent dimer–tetramer equilibrium through crystallographic analysis of recombinant Diocleinae lectins

2007 ◽  
Vol 409 (2) ◽  
pp. 417-428 ◽  
Author(s):  
Celso S. Nagano ◽  
Juan J. Calvete ◽  
Domingo Barettino ◽  
Alicia Pérez ◽  
Benildo S. Cavada ◽  
...  
Keyword(s):  
Structural Information ◽  
Binding Activity ◽  
Crystallographic Analysis ◽  
Structural Basis ◽  
Carbohydrate Binding ◽  
Central Cavity ◽  
Legume Lectin ◽  
Equilibrium Sedimentation ◽  
Ph Dependency ◽  
Ph Dependent

The structural ground underlying the pH-dependency of the dimer–tetramer transition of Diocleinae lectins was investigated by equilibrium sedimentation and X-ray crystal structure determination of wild-type and site-directed mutants of recombinant lectins. Synthetic genes coding for the full-length α-chains of the seed lectins of Dioclea guianensis (termed r-αDguia) and Dioclea grandiflora (termed r-αDGL) were designed and expressed in Escherichia coli. This pioneering approach, which will be described in detail in the present paper, yielded recombinant lectins displaying carbohydrate-binding activity, dimer–tetramer equilibria and crystal structures indistinguishable from their natural homologues. Conversion of the pH-stable tetrameric r-αDGL into a structure exhibiting pH-dependent dimer–tetramer transition was accomplished through mutations that abolished the interdimeric interactions at the central cavity of the tetrameric lectins. Both the central and the peripheral interacting regions bear structural information for formation of the canonical legume lectin tetramer. We hypothesize that the strength of the ionic contacts at these sites may be modulated by the pH, leading to dissociation of those lectin structures that are not locked into a pH-stable tetramer through interdimeric contacts networking the central cavity loops.

Crystal structures of Magnaporthe oryzae trehalose-6-phosphate synthase (MoTps1) suggest a model for catalytic process of Tps1

2019 ◽  
Vol 476 (21) ◽  
pp. 3227-3240 ◽  
Author(s):  
Shanshan Wang ◽  
Yanxiang Zhao ◽  
Long Yi ◽  
Minghe Shen ◽  
Chao Wang ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Conformational Changes ◽  
Magnaporthe Oryzae ◽  
Structural Information ◽  
Complex Structure ◽  
Critical Role ◽  
Catalytic Process ◽  
Structural Basis ◽  
Salt Bridges ◽  
Terminal Domain

Trehalose-6-phosphate (T6P) synthase (Tps1) catalyzes the formation of T6P from UDP-glucose (UDPG) (or GDPG, etc.) and glucose-6-phosphate (G6P), and structural basis of this process has not been well studied. MoTps1 (Magnaporthe oryzae Tps1) plays a critical role in carbon and nitrogen metabolism, but its structural information is unknown. Here we present the crystal structures of MoTps1 apo, binary (with UDPG) and ternary (with UDPG/G6P or UDP/T6P) complexes. MoTps1 consists of two modified Rossmann-fold domains and a catalytic center in-between. Unlike Escherichia coli OtsA (EcOtsA, the Tps1 of E. coli), MoTps1 exists as a mixture of monomer, dimer, and oligomer in solution. Inter-chain salt bridges, which are not fully conserved in EcOtsA, play primary roles in MoTps1 oligomerization. Binding of UDPG by MoTps1 C-terminal domain modifies the substrate pocket of MoTps1. In the MoTps1 ternary complex structure, UDP and T6P, the products of UDPG and G6P, are detected, and substantial conformational rearrangements of N-terminal domain, including structural reshuffling (β3–β4 loop to α0 helix) and movement of a ‘shift region' towards the catalytic centre, are observed. These conformational changes render MoTps1 to a ‘closed' state compared with its ‘open' state in apo or UDPG complex structures. By solving the EcOtsA apo structure, we confirmed that similar ligand binding induced conformational changes also exist in EcOtsA, although no structural reshuffling involved. Based on our research and previous studies, we present a model for the catalytic process of Tps1. Our research provides novel information on MoTps1, Tps1 family, and structure-based antifungal drug design.

Genomic analysis of C-type lectins

2002 ◽  
Vol 69 ◽  
pp. 59-72 ◽  
Author(s):  
Kurt Drickamer ◽  
Andrew J. Fadden
Keyword(s):  
Biological Effects ◽  
Cell Signalling ◽  
Genomic Analysis ◽  
Binding Activity ◽  
Immunoglobulin Superfamily ◽  
Carbohydrate Binding ◽  
Carbohydrate Recognition ◽  
Calcium Dependent ◽  
Binding Domains ◽  
Carbohydrate Recognition Domains

Many biological effects of complex carbohydrates are mediated by lectins that contain discrete carbohydrate-recognition domains. At least seven structurally distinct families of carbohydrate-recognition domains are found in lectins that are involved in intracellular trafficking, cell adhesion, cell–cell signalling, glycoprotein turnover and innate immunity. Genome-wide analysis of potential carbohydrate-binding domains is now possible. Two classes of intracellular lectins involved in glycoprotein trafficking are present in yeast, model invertebrates and vertebrates, and two other classes are present in vertebrates only. At the cell surface, calcium-dependent (C-type) lectins and galectins are found in model invertebrates and vertebrates, but not in yeast; immunoglobulin superfamily (I-type) lectins are only found in vertebrates. The evolutionary appearance of different classes of sugar-binding protein modules parallels a development towards more complex oligosaccharides that provide increased opportunities for specific recognition phenomena. An overall picture of the lectins present in humans can now be proposed. Based on our knowledge of the structures of several of the C-type carbohydrate-recognition domains, it is possible to suggest ligand-binding activity that may be associated with novel C-type lectin-like domains identified in a systematic screen of the human genome. Further analysis of the sequences of proteins containing these domains can be used as a basis for proposing potential biological functions.

scholarly journals Biochemical and Initial Structural Characterization of the Monocot Chimeric Jacalin OsJAC1

2021 ◽  
Vol 22 (11) ◽  
pp. 5639
Author(s):  
Nikolai Huwa ◽  
Oliver H. Weiergräber ◽  
Christian Kirsch ◽  
Ulrich Schaffrath ◽  
Thomas Classen
Keyword(s):  
Physiological Role ◽  
Basic Function ◽  
Binding Activity ◽  
Carbohydrate Binding ◽  
Lectin Domain ◽  
Reducing Conditions ◽  
Transition Points ◽  
The Individual ◽  
High Yields ◽  
Dirigent Domain

The monocot chimeric jacalin OsJAC1 from Oryza sativa consists of a dirigent and a jacalin-related lectin domain. The corresponding gene is expressed in response to different abiotic and biotic stimuli. However, there is a lack of knowledge about the basic function of the individual domains and their contribution to the physiological role of the entire protein. In this study, we have established a heterologous expression in Escherichia coli with high yields for the full-length protein OsJAC1 as well as its individual domains. Our findings showed that the secondary structure of both domains is dominated by β-strand elements. Under reducing conditions, the native protein displayed clearly visible transition points of thermal unfolding at 59 and 85 °C, which could be attributed to the lectin and the dirigent domain, respectively. Our study identified a single carbohydrate-binding site for each domain with different specificities towards mannose and glucose (jacalin domain), and galactose moieties (dirigent domain), respectively. The recognition of different carbohydrates might explain the ability of OsJAC1 to respond to different abiotic and biotic factors. This is the first report of specific carbohydrate-binding activity of a DIR domain, shedding new light on its function in the context of this monocot chimeric jacalin.

Carbohydrate binding, quaternary structure and a novel hydrophobic binding site in two legume lectin oligomers from Dolichos biflorus 1 1Edited by R. Huber

1999 ◽  
Vol 286 (4) ◽  
pp. 1161-1177 ◽  
Author(s):  
Thomas W Hamelryck ◽  
Remy Loris ◽  
Julie Bouckaert ◽  
Minh-Hoa Dao-Thi ◽  
Gerard Strecker ◽  
...  
Keyword(s):  
Binding Site ◽  
Quaternary Structure ◽  
Carbohydrate Binding ◽  
Dolichos Biflorus ◽  
Legume Lectin ◽  
Hydrophobic Binding

scholarly journals Crystallization of and selenomethionine phasing strategy for a SETMAR–DNA complex

2016 ◽  
Vol 72 (9) ◽  
pp. 713-719 ◽  
Author(s):  
Qiujia Chen ◽  
Millie Georgiadis
Keyword(s):  
Dna Binding ◽  
Catalytic Domain ◽  
Specific Binding ◽  
Critical Role ◽  
Binding Activity ◽  
Structural Basis ◽  
Unexpected Finding ◽  
Terminal Inverted Repeat ◽  
Dna Binding Activity ◽  
New Genes

Transposable elements have played a critical role in the creation of new genes in all higher eukaryotes, including humans. Although the chimeric fusion protein SETMAR is no longer active as a transposase, it contains both the DNA-binding domain (DBD) and catalytic domain of theHsmar1transposase. The amino-acid sequence of the DBD has been virtually unchanged in 50 million years and, as a consequence, SETMAR retains its sequence-specific binding to the ancestralHsmar1terminal inverted repeat (TIR) sequence. Thus, the DNA-binding activity of SETMAR is likely to have an important biological function. To determine the structural basis for the recognition of TIR DNA by SETMAR, the design of TIR-containing oligonucleotides and SETMAR DBD variants, crystallization of DBD–DNA complexes, phasing strategies and initial phasing experiments are reported here. An unexpected finding was that oligonucleotides containing two BrdUs in place of thymidines produced better quality crystals in complex with SETMAR than their natural counterparts.

scholarly journals Structural Basis for Linezolid Binding Site Rearrangement in the Staphylococcus aureus Ribosome

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Matthew J. Belousoff ◽  
Zohar Eyal ◽  
Mazdak Radjainia ◽  
Tofayel Ahmed ◽  
Rebecca S. Bamert ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Structural Information ◽  
Structural Basis ◽  
Common Mechanism ◽  
Resistance Mutations ◽  
Antimicrobial Drugs ◽  
Linezolid Resistance ◽  
Drug Modification ◽  
Antibiotic Resistance Mutations ◽  
Shed Light

ABSTRACT An unorthodox, surprising mechanism of resistance to the antibiotic linezolid was revealed by cryo-electron microscopy (cryo-EM) in the 70S ribosomes from a clinical isolate of Staphylococcus aureus. This high-resolution structural information demonstrated that a single amino acid deletion in ribosomal protein uL3 confers linezolid resistance despite being located 24 Å away from the linezolid binding pocket in the peptidyl-transferase center. The mutation induces a cascade of allosteric structural rearrangements of the rRNA that ultimately results in the alteration of the antibiotic binding site. IMPORTANCE The growing burden on human health caused by various antibiotic resistance mutations now includes prevalent Staphylococcus aureus resistance to last-line antimicrobial drugs such as linezolid and daptomycin. Structure-informed drug modification represents a frontier with respect to designing advanced clinical therapies, but success in this strategy requires rapid, facile means to shed light on the structural basis for drug resistance (D. Brown, Nat Rev Drug Discov 14:821–832, 2015, https://doi.org/10.1038/nrd4675 ). Here, detailed structural information demonstrates that a common mechanism is at play in linezolid resistance and provides a step toward the redesign of oxazolidinone antibiotics, a strategy that could thwart known mechanisms of linezolid resistance. IMPORTANCE The growing burden on human health caused by various antibiotic resistance mutations now includes prevalent Staphylococcus aureus resistance to last-line antimicrobial drugs such as linezolid and daptomycin. Structure-informed drug modification represents a frontier with respect to designing advanced clinical therapies, but success in this strategy requires rapid, facile means to shed light on the structural basis for drug resistance (D. Brown, Nat Rev Drug Discov 14:821–832, 2015, https://doi.org/10.1038/nrd4675 ). Here, detailed structural information demonstrates that a common mechanism is at play in linezolid resistance and provides a step toward the redesign of oxazolidinone antibiotics, a strategy that could thwart known mechanisms of linezolid resistance.

scholarly journals YopT domain of the PfhB2 toxin from Pasteurella multocida: protein expression, characterization, crystallization and crystallographic analysis

2018 ◽  
Vol 74 (3) ◽  
pp. 128-134
Author(s):  
Sanjeev Kumar ◽  
Victoria Hedrick ◽  
Seema Mattoo
Keyword(s):  
Pasteurella Multocida ◽  
Opportunistic Infections ◽  
Structural Information ◽  
Sequence Similarity ◽  
Catalytic Triad ◽  
Crystallographic Analysis ◽  
High Sequence Similarity ◽  
Data Set ◽  
Cell Parameters ◽  
Tract Infections

Pasteurella multocida causes respiratory-tract infections in a broad range of animals, as well as opportunistic infections in humans. P. multocida secretes a multidomain toxin called PfhB2, which contains a YopT-like cysteine protease domain at its C-terminus. The YopT domain of PfhB2 contains a well conserved Cys–His–Asp catalytic triad that defines YopT family members, and shares high sequence similarity with the prototype YopT from Yersinia sp. To date, only one crystal structure of a YopT family member has been reported; however, additional structural information is needed to help characterize the varied substrate specificity and enzymatic action of this large protease family. Here, a catalytically inactive C3733S mutant of PfhB2 YopT that provides enhanced protein stability was used with the aim of gaining structural insight into the diversity within the YopT protein family. To this end, the C3733S mutant of PfhB2 YopT has been successfully cloned, overexpressed, purified and crystallized. Diffraction data sets were collected from native crystals to 3.5 Å resolution and a single-wavelength anomalous data set was collected from an iodide-derivative crystal to 3.2 Å resolution. Data pertaining to crystals belonging to space group P31, with unit-cell parameters a = 136.9, b = 136.9, c = 74.7 Å for the native crystals and a = 139.2, b = 139.2, c = 74.7 Å for the iodide-derivative crystals, are discussed.

Sign in / Sign up

Export Citation Format

Share Document