scholarly journals Structural basis of binding and inhibition of ornithine decarboxylase by 1-amino-oxy-3-aminopropane

2021 ◽  
Author(s):  
X Edward Zhou ◽  
Kelly Suino-Powell ◽  
Chad R Schultz ◽  
Bilal Aleiwi ◽  
Joseph S Brunzelle ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Ornithine Decarboxylase ◽  
Complex Structure ◽  
Binding Pocket ◽  
Catalytic Site ◽  
Structural Basis ◽  
High Potency ◽  
Substrate Binding Pocket ◽  
Rate Limiting

Ornithine decarboxylase (ODC) is the rate-limiting enzyme for the synthesis of polyamines (PAs). PAs are oncometabolites that are required for proliferation, and pharmaceutical ODC inhibition is pursued for the treatment of hyperproliferative diseases, including cancer and infectious diseases. The most potent ODC inhibitor is 1-amino-oxy-3-aminopropane (APA). A previous crystal structure of an ODC–APA complex indicated that APA non-covalently binds ODC and its cofactor pyridoxal 5-phosphate (PLP) and functions by competing with the ODC substrate ornithine for binding to the catalytic site. We have revisited the mechanism of APA binding and ODC inhibition through a new crystal structure of APA-bound ODC, which we solved at 2.49 Å resolution. The structure unambiguously shows the presence of a covalent oxime between APA and PLP in the catalytic site, which we confirmed in solution by mass spectrometry. The stable oxime makes extensive interactions with ODC but cannot be catabolized, explaining APA’s high potency in ODC inhibition. In addition, we solved an ODC/PLP complex structure with citrate bound at the substrate binding pocket. These two structures provide new structural scaffolds for developing more efficient pharmaceutical ODC inhibitors.

scholarly journals Structure-based analysis of the molecular interactions between acyltransferase and acyl carrier protein in vicenistatin biosynthesis

2016 ◽  
Vol 113 (7) ◽  
pp. 1802-1807 ◽  
Author(s):  
Akimasa Miyanaga ◽  
Shohei Iwasawa ◽  
Yuji Shinohara ◽  
Fumitaka Kudo ◽  
Tadashi Eguchi
Keyword(s):  
Crystal Structure ◽  
Protein Interactions ◽  
Acyl Carrier Protein ◽  
Complex Structure ◽  
Binding Pocket ◽  
Carrier Protein ◽  
Protein Protein Interactions ◽  
Substrate Binding Pocket ◽  
Insight Into

Acyltransferases (ATs) are key determinants of building block specificity in polyketide biosynthesis. Despite the importance of protein–protein interactions between AT and acyl carrier protein (ACP) during the acyltransfer reaction, the mechanism of ACP recognition by AT is not understood in detail. Herein, we report the crystal structure of AT VinK, which transfers a dipeptide group between two ACPs, VinL and VinP1LdACP, in vicenistatin biosynthesis. The isolated VinK structure showed a unique substrate-binding pocket for the dipeptide group linked to ACP. To gain greater insight into the mechanism of ACP recognition, we attempted to crystallize the VinK–ACP complexes. Because transient enzyme–ACP complexes are difficult to crystallize, we developed a covalent cross-linking strategy using a bifunctional maleimide reagent to trap the VinK–ACP complexes, allowing the determination of the crystal structure of the VinK–VinL complex. In the complex structure, Arg-153, Met-206, and Arg-299 of VinK interact with the negatively charged helix II region of VinL. The VinK–VinL complex structure allows, to our knowledge, the first visualization of the interaction between AT and ACP and provides detailed mechanistic insights into ACP recognition by AT.

scholarly journals Crystal structure of steroid reductase SRD5A reveals conserved steroid reduction mechanism

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yufei Han ◽  
Qian Zhuang ◽  
Bo Sun ◽  
Wenping Lv ◽  
Sheng Wang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Biochemical Characterization ◽  
Substrate Binding ◽  
Binding Pocket ◽  
Substrate Binding Pocket ◽  
Transmembrane Segments ◽  
Therapeutic Molecules ◽  
Binding Cavity ◽  
Immune System Regulation ◽  
Mediated Reduction

AbstractSteroid hormones are essential in stress response, immune system regulation, and reproduction in mammals. Steroids with 3-oxo-Δ4 structure, such as testosterone or progesterone, are catalyzed by steroid 5α-reductases (SRD5As) to generate their corresponding 3-oxo-5α steroids, which are essential for multiple physiological and pathological processes. SRD5A2 is already a target of clinically relevant drugs. However, the detailed mechanism of SRD5A-mediated reduction remains elusive. Here we report the crystal structure of PbSRD5A from Proteobacteria bacterium, a homolog of both SRD5A1 and SRD5A2, in complex with the cofactor NADPH at 2.0 Å resolution. PbSRD5A exists as a monomer comprised of seven transmembrane segments (TMs). The TM1-4 enclose a hydrophobic substrate binding cavity, whereas TM5-7 coordinate cofactor NADPH through extensive hydrogen bonds network. Homology-based structural models of HsSRD5A1 and -2, together with biochemical characterization, define the substrate binding pocket of SRD5As, explain the properties of disease-related mutants and provide an important framework for further understanding of the mechanism of NADPH mediated steroids 3-oxo-Δ4 reduction. Based on these analyses, the design of therapeutic molecules targeting SRD5As with improved specificity and therapeutic efficacy would be possible.

scholarly journals Structural basis of antigen recognition: crystal structure of duck egg lysozyme

2017 ◽  
Vol 73 (11) ◽  
pp. 910-920 ◽  
Author(s):  
David Brent Langley ◽  
Ben Crossett ◽  
Peter Schofield ◽  
Jenny Jackson ◽  
Mahdi Zeraati ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Binding Affinity ◽  
Anas Platyrhynchos ◽  
Antigen Recognition ◽  
Pekin Duck ◽  
Structural Basis ◽  
Primary Sequence ◽  
Duck Egg ◽  
Differential Affinity

Duck egg lysozyme (DEL) is a widely used model antigen owing to its capacity to bind with differential affinity to anti-chicken egg lysozyme antibodies. However, no structures of DEL have so far been reported, and the situation had been complicated by the presence of multiple isoforms and conflicting reports of primary sequence. Here, the structures of two DEL isoforms from the eggs of the commonly used Pekin duck (Anas platyrhynchos) are reported. Using structural analyses in combination with mass spectrometry, non-ambiguous DEL primary sequences are reported. Furthermore, the structures and sequences determined here enable rationalization of the binding affinity of DEL for well documented landmark anti-lysozyme antibodies.

Structural insights into the substrate specificity of a glycoside hydrolase family 5 lichenase from Caldicellulosiruptor sp. F32

2017 ◽  
Vol 474 (20) ◽  
pp. 3373-3389 ◽  
Author(s):  
Dong-Dong Meng ◽  
Xi Liu ◽  
Sheng Dong ◽  
Ye-Fei Wang ◽  
Xiao-Qing Ma ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Substrate Specificity ◽  
Glycoside Hydrolase ◽  
Complex Structure ◽  
Dynamics Simulation ◽  
Structural Basis ◽  
Glycoside Hydrolase Family ◽  
Substrate Selectivity ◽  
Glucose Residue ◽  
Structural Insights

Glycoside hydrolase (GH) family 5 is one of the largest GH families with various GH activities including lichenase, but the structural basis of the GH5 lichenase activity is still unknown. A novel thermostable lichenase F32EG5 belonging to GH5 was identified from an extremely thermophilic bacterium Caldicellulosiruptor sp. F32. F32EG5 is a bi-functional cellulose and a lichenan-degrading enzyme, and exhibited a high activity on β-1,3-1,4-glucan but side activity on cellulose. Thin-layer chromatography and NMR analyses indicated that F32EG5 cleaved the β-1,4 linkage or the β-1,3 linkage while a 4-O-substitued glucose residue linked to a glucose residue through a β-1,3 linkage, which is completely different from extensively studied GH16 lichenase that catalyses strict endo-hydrolysis of the β-1,4-glycosidic linkage adjacent to a 3-O-substitued glucose residue in the mixed-linked β-glucans. The crystal structure of F32EG5 was determined to 2.8 Å resolution, and the crystal structure of the complex of F32EG5 E193Q mutant and cellotetraose was determined to 1.7 Å resolution, which revealed that the exit subsites of substrate-binding sites contribute to both thermostability and substrate specificity of F32EG5. The sugar chain showed a sharp bend in the complex structure, suggesting that a substrate cleft fitting to the bent sugar chains in lichenan is a common feature of GH5 lichenases. The mechanism of thermostability and substrate selectivity of F32EG5 was further demonstrated by molecular dynamics simulation and site-directed mutagenesis. These results provide biochemical and structural insights into thermostability and substrate selectivity of GH5 lichenases, which have potential in industrial processes.

scholarly journals Structural basis of AdoMet-dependent aminocarboxypropyl transfer reaction catalyzed by tRNA-wybutosine synthesizing enzyme, TYW2

2009 ◽  
Vol 106 (37) ◽  
pp. 15616-15621 ◽  
Author(s):  
Masataka Umitsu ◽  
Hiroshi Nishimasu ◽  
Akiko Noma ◽  
Tsutomu Suzuki ◽  
Ryuichiro Ishitani ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Binding Pocket ◽  
Structural Basis ◽  
Binding Modes ◽  
Substrate Binding Pocket ◽  
Methyl Group ◽  
Group Transfer ◽  
Canonical Class ◽  
Functional Analyses

S-adenosylmethionine (AdoMet) is a methyl donor used by a wide variety of methyltransferases, and it is also used as the source of an α-amino-α-carboxypropyl (“acp”) group by several enzymes. tRNA-yW synthesizing enzyme-2 (TYW2) is involved in the biogenesis of a hypermodified nucleotide, wybutosine (yW), and it catalyzes the transfer of the “acp” group from AdoMet to the C7 position of the imG-14 base, a yW precursor. This modified nucleoside yW is exclusively located at position 37 of eukaryotic tRNAPhe, and it ensures the anticodon-codon pairing on the ribosomal decoding site. Although this “acp” group has a significant role in preventing decoding frame shifts, the mechanism of the “acp” group transfer by TYW2 remains unresolved. Here we report the crystal structures and functional analyses of two archaeal homologs of TYW2 from Pyrococcus horikoshii and Methanococcus jannaschii. The in vitro mass spectrometric and radioisotope-labeling analyses confirmed that these archaeal TYW2 homologues have the same activity as yeast TYW2. The crystal structures verified that the archaeal TYW2 contains a canonical class-I methyltransferase (MTase) fold. However, their AdoMet-bound structures revealed distinctive AdoMet-binding modes, in which the “acp” group, instead of the methyl group, of AdoMet is directed to the substrate binding pocket. Our findings, which were confirmed by extensive mutagenesis studies, explain why TYW2 transfers the “acp” group, and not the methyl group, from AdoMet to the nucleobase.

scholarly journals Crystal structure and mechanism of human carboxypeptidase O: Insights into its specific activity for acidic residues

2018 ◽  
Vol 115 (17) ◽  
pp. E3932-E3939 ◽  
Author(s):  
Maria C. Garcia-Guerrero ◽  
Javier Garcia-Pardo ◽  
Esther Berenguer ◽  
Roberto Fernandez-Alvarez ◽  
Gifty B. Barfi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Specific Activity ◽  
Dominant Role ◽  
Substrate Binding ◽  
Digestive Enzyme ◽  
Binding Pocket ◽  
Site Directed Mutagenesis ◽  
Enzyme Specificity ◽  
Substrate Binding Pocket ◽  
Acidic Residues

Human metallocarboxypeptidase O (hCPO) is a recently discovered digestive enzyme localized to the apical membrane of intestinal epithelial cells. Unlike pancreatic metallocarboxypeptidases, hCPO is glycosylated and produced as an active enzyme with distinctive substrate specificity toward C-terminal (C-t) acidic residues. Here we present the crystal structure of hCPO at 1.85-Å resolution, both alone and in complex with a carboxypeptidase inhibitor (NvCI) from the marine snail Nerita versicolor. The structure provides detailed information regarding determinants of enzyme specificity, in particular Arg275, placed at the bottom of the substrate-binding pocket. This residue, located at “canonical” position 255, where it is Ile in human pancreatic carboxypeptidases A1 (hCPA1) and A2 (hCPA2) and Asp in B (hCPB), plays a dominant role in determining the preference of hCPO for acidic C-t residues. Site-directed mutagenesis to Asp and Ala changes the specificity to C-t basic and hydrophobic residues, respectively. The single-site mutants thus faithfully mimic the enzymatic properties of CPB and CPA, respectively. hCPO also shows a preference for Glu over Asp, probably as a consequence of a tighter fitting of the Glu side chain in its S1′ substrate-binding pocket. This unique preference of hCPO, together with hCPA1, hCPA2, and hCPB, completes the array of C-t cleavages enabling the digestion of the dietary proteins within the intestine. Finally, in addition to activity toward small synthetic substrates and peptides, hCPO can also trim C-t extensions of proteins, such as epidermal growth factor, suggesting a role in the maturation and degradation of growth factors and bioactive peptides.

scholarly journals Structural basis for the inhibition of poly(ADP-ribose) polymerases 1 and 2 by BMN 673, a potent inhibitor derived from dihydropyridophthalazinone

2014 ◽  
Vol 70 (9) ◽  
pp. 1143-1149 ◽  
Author(s):  
Mika Aoyagi-Scharber ◽  
Anna S. Gardberg ◽  
Bryan K. Yip ◽  
Bing Wang ◽  
Yuqiao Shen ◽  
...  
Keyword(s):  
Binding Pocket ◽  
Clinical Development ◽  
Structural Basis ◽  
Water Molecules ◽  
The Novel ◽  
Breast Cancers ◽  
High Potency ◽  
Damage Response ◽  
Site Water ◽  
Inhibitor Selectivity

Poly(ADP-ribose) polymerases 1 and 2 (PARP1 and PARP2), which are involved in DNA damage response, are targets of anticancer therapeutics. BMN 673 is a novel PARP1/2 inhibitor with substantially increased PARP-mediated tumor cytotoxicity and is now in later-stage clinical development for BRCA-deficient breast cancers. In co-crystal structures, BMN 673 is anchored to the nicotinamide-binding pocketviaan extensive network of hydrogen-bonding and π-stacking interactions, including those mediated by active-site water molecules. The novel di-branched scaffold of BMN 673 extends the binding interactions towards the outer edges of the pocket, which exhibit the least sequence homology among PARP enzymes. The crystallographic structural analyses reported here therefore not only provide critical insights into the molecular basis for the exceptionally high potency of the clinical development candidate BMN 673, but also new opportunities for increasing inhibitor selectivity.

scholarly journals The Structural Basis for Glycerol Permeation by human AQP7

2019 ◽  
Author(s):  
Li Zhang ◽  
Deqiang Yao ◽  
Fu Zhou ◽  
Qing Zhang ◽  
Ying Xia ◽  
...  
Keyword(s):  
Physiological Condition ◽  
Critical Role ◽  
Binding Pocket ◽  
Structural Basis ◽  
Glycerol Metabolism ◽  
Functional Assay ◽  
Substrate Binding Pocket ◽  
Glycerol Molecule ◽  
Cytoplasmic Side

AbstractHuman glycerol channel AQP7 conducts glycerol release from adipocyte and entry into the cells in pancreatic islets, muscles and kidney tubule, and thus regulate glycerol metabolism in those tissues. Compared with other human aquaglyceroporins, AQP7 shows a less conserved “NPA” motif in the center cavity, and a pair of aromatic residues at Ar/R selectivity filter. To understand the structural basis for the glycerol conductance, we crystallized the human AQP7 and determined the structure at 3.7 Å. A substrate binding pocket was found near to the Ar/R filter and the bound glycerol molecule stabilized by R229. In vivo functional assay on human AQP7 as well as AQP3 and AQP10 demonstrated strong glycerol transportation activities at physiological condition. The human AQP7 structure reveals a fully closed conformation with its permeation pathway strictly confined by Ar/R filter at the exoplasmic side and the gate at the cytoplasmic side, and the dislocation of the residues at narrowest parts of glycerol pathway in AQP7 play a critical role in controlling the glycerol flux.

scholarly journals Crystal structure of Arabidopsis thaliana HPPK/DHPS, a bifunctional enzyme and target of the herbicide asulam

2021 ◽  
Author(s):  
Grishma Vadlamani ◽  
Kirill V Sukhoverkov ◽  
Joel Haywood ◽  
Karen J Breese ◽  
Mark F Fisher ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Arabidopsis Thaliana ◽  
Mode Of Action ◽  
Rational Design ◽  
Binding Pocket ◽  
Structural Basis ◽  
Metabolic Resistance ◽  
Folate Biosynthesis ◽  
Limited Opportunity ◽  
Regulatory Scrutiny

Herbicides are vital for modern agriculture, but their utility is threatened by genetic or metabolic resistance in weeds as well as heightened regulatory scrutiny. Of the known herbicide modes of action, 6-hydroxymethyl-7,8-dihydropterin synthase (DHPS) which is involved in folate biosynthesis, is targeted by just one commercial herbicide, asulam. A mimic of the substrate para-aminobenzoic acid, asulam is chemically similar to sulfonamide antibiotics - and while still in widespread use, asulam has faced regulatory scrutiny. With an entire mode of action represented by just one commercial agrochemical, we sought to improve the understanding of its plant target. Here we solve a 2.6 Å resolution crystal structure for Arabidopsis thaliana DHPS that is conjoined to 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) and reveal a strong structural conservation with bacterial counterparts at the sulfonamide-binding pocket of DHPS. We demonstrate asulam and the antibiotics sulfacetamide and sulfamethoxazole have herbicidal as well as antibacterial activity and explore the structural basis of their potency by modelling these compounds in mitochondrial HPPK/DHPS. Our findings suggest limited opportunity for the rational design of plant selectivity from asulam and that pharmacokinetic or delivery differences between plants and microbes might be the best approaches to safeguard this mode of action.

scholarly journals Crystal structure of TchmY from Actinoplanes teichomyceticus

2019 ◽  
Vol 75 (9) ◽  
pp. 570-575
Author(s):  
Zhenzhen Yang ◽  
Lilan Zhang ◽  
Xuejing Yu ◽  
Shan Wu ◽  
Yong Yang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Gene Clusters ◽  
Binding Pocket ◽  
Animal Nutrition ◽  
Biosynthetic Pathways ◽  
Substrate Binding Pocket ◽  
Actinoplanes Teichomyceticus ◽  
Unknown Sequence ◽  
Potential Substrate

Moenomycin-type antibiotics are phosphoglycolipids that are notable for their unique modes of action and have proven to be useful in animal nutrition. The gene clusters tchm from Actinoplanes teichomyceticus and moe from Streptomyces are among a limited number of known moenomycin-biosynthetic pathways. Most genes in tchm have counterparts in the moe cluster, except for tchmy and tchmz, the functions of which remain unknown. Sequence analysis indicates that TchmY belongs to the isoprenoid enzyme C2-like superfamily and may serve as a prenylcyclase. The enzyme was proposed to be involved in terminal cyclization of the moenocinyl chain in teichomycin, leading to the diumycinol chain of moenomycin isomers. Here, recombinant TchmY protein was expressed in Escherichia coli and its crystal structure was solved by SIRAS. Structural analysis and comparison with other prenylcyclases were performed. The overall fold of TchmY consists of an (α/α)6-barrel, and a potential substrate-binding pocket is found in the central chamber. These results should provide important information regarding the biosynthetic basis of moenomycin antibiotics.

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