ABSTRACT
Eukaryotic DNA clamp is a trimeric protein featuring a toroidal ring structure that binds DNA on the inside of the ring and multiple proteins involved in DNA transactions on the outside. Eukaryotes have two types of DNA clamps: the replication clamp PCNA and the checkpoint clamp RAD9-RAD1-HUS1 (9-1-1). 9-1-1 activates the ATR-CHK1 pathway in DNA damage checkpoint, regulating cell cycle progression. Structure of 9-1-1 consists of two moieties: a hetero-trimeric ring formed by PCNA-like domains of three subunits and an intrinsically disordered C-terminal region of the RAD9 subunit, called RAD9 C-tail. The RAD9 C-tail interacts with the 9-1-1 ring and disrupts the interaction between 9-1-1 and DNA, suggesting a negative regulatory role for this intramolecular interaction. In contrast, RHINO, a 9-1-1 binding protein, interacts with both RAD1 and RAD9 subunits, positively regulating checkpoint activation by 9-1-1. This study presents a biochemical and structural analysis of intra- and inter-molecular interactions on the 9-1-1 ring. Biochemical analysis indicates that RAD9 C-tail binds to the hydrophobic pocket on the PCNA-like domain of RAD9, implying that the pocket is involved in multiple protein-protein interactions. The crystal structure of the 9-1-1 ring in complex with a RHINO peptide reveals that RHINO binds to the hydrophobic pocket of RAD9, shedding light on the RAD9-binding motif. Additionally, the study proposes a structural model of the 9-1-1-RHINO quaternary complex. Together, these findings provide functional insights into the intra- and inter-molecular interactions on the front side of RAD9, elucidating the roles of RAD9 C-tail and RHINO in checkpoint activation.
Subject(s)
Carrier Proteins , Cell Cycle Proteins , Multiprotein Complexes , Protein Subunits , Humans , Carrier Proteins/metabolism , Cell Cycle Proteins/chemistry , Cell Cycle Proteins/metabolism , Checkpoint Kinase 1 , DNA/metabolism , DNA Damage , DNA Repair , Hydrophobic and Hydrophilic Interactions , Multiprotein Complexes/chemistry , Multiprotein Complexes/metabolism , Proliferating Cell Nuclear Antigen/metabolism , Protein Subunits/chemistry , Protein Subunits/metabolism , Protein DomainsABSTRACT
Natural products are important sources of seed compounds for drug discovery. However, it has become difficult in recent years to discover new compounds with valuable pharmacological activities. On the other hand, among the vast number of natural products that have been isolated so far, a considerable number of compounds with specific biological activities are thought to be overlooked in screening that uses biological activity as an index. Therefore, it is conceivable that such overlooked useful compounds may be found by screening compound libraries that have been amassed previously through specific assays. Previously, NPD723, a member of the Natural Products Depository library comprised of a mixture of natural and non-natural products developed at RIKEN, and its metabolite H-006 were found to inhibit growth of various cancer cells at low nanomolar half-maximal inhibitory concentration. Subsequent analysis revealed that H-006 strongly inhibited human dihydroorotate dehydrogenase (DHODH), the rate-limiting enzyme in the de novo pyrimidine biosynthetic pathway. Here, we elucidated the crystal structure of the DHODH-flavin mononucleotide-orotic acid-H-006 complex at 1.7 Å resolution to determine that furocoumavirin, the S-enantiomer of H-006, was the actual inhibitor. The overall mode of interaction of furocoumavirin with the inhibitor binding pocket was similar to that described for previously reported tight-binding inhibitors. However, the structural information together with kinetic characterizations of site-specific mutants identified key unique features that are considered to contribute to the sub-nanomolar inhibition of DHODH by furocoumavirin. Our finding identified new chemical features that could improve the design of human DHODH inhibitors.
Subject(s)
Antiviral Agents , Dihydroorotate Dehydrogenase , Humans , Antiviral Agents/pharmacology , Antiviral Agents/chemistry , Crystallography, X-Ray , Dihydroorotate Dehydrogenase/antagonists & inhibitors , Dihydroorotate Dehydrogenase/chemistry , Enzyme Inhibitors/pharmacology , Enzyme Inhibitors/chemistry , Furocoumarins/pharmacology , Furocoumarins/chemistry , Models, MolecularABSTRACT
The RAD9-RAD1-HUS1 complex (9-1-1) is a eukaryotic DNA clamp with a crucial role at checkpoints for DNA damage. The ring-like structure of 9-1-1 is opened for loading onto 5' recessed DNA by the clamp loader RAD17 RFC-like complex (RAD17-RLC), in which the RAD17 subunit is responsible for specificity to 9-1-1. Loading of 9-1-1 is required for activation of the ATR-CHK1 checkpoint pathway and the activation is stimulated by a 9-1-1 interacting protein, RHINO, which interacts with 9-1-1 via a recently identified RAD1-binding motif. This discovery led to the hypothesis that other interacting proteins may contain a RAD1-binding motif as well. Here, we show that vertebrate RAD17 proteins also have a putative RAD1-binding motif in their N-terminal regions, and we report the crystal structure of human 9-1-1 bound to a human RAD17 peptide incorporating the motif at 2.1 Å resolution. Our structure confirms that the N-terminal region of RAD17 binds to the RAD1 subunit of 9-1-1 via specific interactions. Furthermore, we show that the RAD1-binding motif of RHINO disturbs the interaction of the N-terminal region of RAD17 with 9-1-1. Our results provide deeper understanding of how RAD17-RLC specifically recognizes 9-1-1 and imply that RHINO has a functional role in 9-1-1 loading/unloading and checkpoint activation.
Subject(s)
Carrier Proteins , Cell Cycle Proteins , Exonucleases , Humans , Carrier Proteins/metabolism , Cell Cycle Proteins/metabolism , DNA/metabolism , DNA Damage , DNA-Binding Proteins/metabolism , Exonucleases/metabolismABSTRACT
(-)-FR901483 (1) isolated from the fungus Cladobotryum sp. No.11231 achieves immunosuppression via nucleic acid biosynthesis inhibition rather than IL-2 production inhibition as accomplished by FK506 and cyclosporin A. Recently, we identified the frz gene cluster for the biosynthesis of 1. It contains frzK, a gene homologous to phosphoribosyl pyrophosphate amidotransferase (PPAT)that catalyzes the initial step of de novo purine biosynthesis. We speculated that frzK encodes a PPAT that escapes inhibition by 1 and functions as a self-resistance enzyme (SRE) for the producing host. Nevertheless, details remained elusive. Here, we report the biochemical and structural analyses of FrzK and its Escherichia coli counterpart, PurF. Recombinantly produced FrzK exhibited PPAT activity, albeit weaker than PurF, but evaded strong inhibition by 1. These results confirmed that the target of 1 is PPAT, and FrzK acts as an SRE by maintaining the de novo purine biosynthetic capability in the presence of 1. To understand how FrzK evades inhibition by 1, we determined the crystal structure of PurF in the complex with 1 and constructed a homology model of FrzK. Sequence and structural analyses of various PPATs identified that many residues unique to FrzK occur near the Flexible Loop that remains disordered when inactive but becomes ordered and covers up the active site upon activation by substrate binding. Kinetic characterizations of mutants of the unique residues revealed that the resistance of FrzK against 1 may be conferred by structurally predisposing the Flexible Loop to the active, closed conformation even in the presence of 1.
Subject(s)
Amidophosphoribosyltransferase , Purines , Amino Acid Sequence , Purines/chemistry , Amidophosphoribosyltransferase/genetics , Amidophosphoribosyltransferase/metabolism , Escherichia coli/metabolismABSTRACT
A 72-year-old man with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) was treated with dasatinib (week1: 50 mg/day, week2: 70 mg/day, week3-: 100 mg/day) and prednisolone from June 2017. However, in January 2018, it relapsed with the T315I mutation. Although the treatment was changed to ponatinib 30 mg/day, he experienced a second relapse in June 2018. Following confirmation of CD22 positivity, he was treated with three cycles of inotuzumab ozogamicin (InO), resulting in CR. He was CR for 2.9 years before relapsing for the third time in May 2021. Because the patient was still CD22-positive, InO was given again, and the patient achieved CR at the end of the second cycle. We had a case where re-administering InO was effective as a salvage therapy for relapsed/refractory Ph+ALL (r/r Ph+ALL) in an elderly patient.
Subject(s)
Philadelphia Chromosome , Precursor Cell Lymphoblastic Leukemia-Lymphoma , Aged , Male , Humans , Inotuzumab Ozogamicin/therapeutic use , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Retreatment , DasatinibABSTRACT
Oligopeptide permease A (OppA) plays an important role in the nutrition of cells and various signaling processes. In archaea, OppA is a major protein present in membrane vesicles of Thermococcales. Because there being no crystal structures of archaeal OppAs determined to date, we report the crystal structure of archaeal OppA from Thermococcus kodakaraensis (TkOppA) at 2.3 Å resolution by the single-wavelength anomalous dispersion method. TkOppA consists of three domains similarly to bacterial OppAs, and the inserted regions not present in bacterial OppAs are at the periphery of the core region. An endogenous pentapeptide was bound in the pocket of domains I and III of TkOppA by hydrogen bonds of main-chain atoms of the peptide and hydrophobic interactions. No hydrogen bonds of side-chain atoms of the peptide were observed; thus, TkOppA may have low peptide selectivity but some preference for residues 2 and 3. TkOppA has a relatively large pocket and can bind a nonapeptide; therefore, it is suitable for the binding of large peptides similarly to OppAs of Gram-positive bacteria.
Subject(s)
Lipoproteins , Thermococcus , Bacterial Proteins/chemistry , Carrier Proteins/chemistry , Lipoproteins/chemistry , Membrane Transport Proteins/metabolism , Oligopeptides/chemistry , Peptides/metabolismABSTRACT
BACKGROUND: Probability of cure is important for patients with lung metastasis who must decide whether to undergo metastasectomy. Although progression-free survival (PFS) is thought to reflect this, it does not include curative effects by repeat metastasectomy. Thus, the authors developed a new indicator, time to incurable recurrence (TTIR), in which only incurable recurrence was set as an event that included death, with incurable recurrence defined as recurrence not treated by definitive local therapy (DLT), recurrence treated by DLT but with PFS maintained less than 2 years, or recurrence followed by re-recurrence. METHODS: This multi-institutional study included 339 patients who underwent lung metastasectomy for colorectal cancer between 1990 and 2008. RESULTS: Among the 339 patients, 191 experienced recurrence, 77 received DLT for recurrence, 38 had a PFS of 2 years or longer after the treatment, and 33 had maintained a PFS at the last follow-up date. The patients had PFS ranging from 39 to 212 months (median, 101 months). The 5-year OS, PFS, and TTIR rates were respectively 63.4%, 42.2%, and 51.9%. The TTIR curve was similar to the OS curve 7 years after the initial metastasectomy. The difference between TTIR and PFS at 7 years was 9.7%, indicating probability of cure by repeat DLT. Multivariable analysis showed different prognostic factors among OS, PFS, and TTIR. CONCLUSION: At the initial metastasectomy, TTIR may reflect probability of a cure, including cure by repeat DLT, and can be used to analyze prognostic factors associated with cure.
Subject(s)
Colorectal Neoplasms , Lung Neoplasms , Metastasectomy , Colorectal Neoplasms/surgery , Humans , Lung Neoplasms/surgery , Neoplasm Recurrence, Local/surgery , Pneumonectomy , Probability , Prognosis , Progression-Free Survival , Retrospective StudiesABSTRACT
DNA clamp, a highly conserved ring-shaped protein, binds dsDNA within its central pore. Also, DNA clamp interacts with various nuclear proteins on its front, thereby stimulating their enzymatic activities and biological functions. It has been assumed that the DNA clamp is a functionally single-faced ring from bacteria to humans. Here, we report the crystal structure of the heterotrimeric RAD9-RAD1-HUS1 (9-1-1) checkpoint clamp bound to a peptide of RHINO, a recently identified cancer-related protein that interacts with 9-1-1 and promotes activation of the DNA damage checkpoint. This is the first structure of 9-1-1 bound to its partner. The structure reveals that RHINO is unexpectedly bound to the edge and around the back of the 9-1-1 ring through specific interactions with the RAD1 subunit of 9-1-1. Our finding indicates that 9-1-1 is a functionally double-faced DNA clamp.
Subject(s)
Cell Cycle , DNA/metabolism , Peptides/metabolism , Protein Subunits/chemistry , Protein Subunits/metabolism , Amino Acid Sequence , Cell Cycle Proteins/chemistry , Cell Cycle Proteins/metabolism , Humans , Models, Molecular , Peptides/chemistry , Protein BindingABSTRACT
Epidithiodiketopiperazines (ETPs) are a class of ecologically and medicinally important cyclodipeptides bearing a reactive transannular disulfide bridge. Aspirochlorine, an antifungal and toxic ETP isolated from Aspergillus oryzae used in sake brewing, deviates from the common ETP scaffold owing to its unusual ring-enlarged disulfide bridge linked to a spiroaminal ring system. Although this disulfide ring system is implicated in the biological activity of ETPs the biochemical basis for this derailment has remained a mystery. Here we report the discovery of a novel oxidoreductase (AclR) that represents the first-in-class enzyme catalyzing both a carbon-sulfur bond migration and spiro-ring formation, and that the acl pathway involves a cryptic acetylation as a prerequisite for the rearrangement. Genetic screening in A. oryzae identified aclR as the candidate for the complex biotransformation, and the aclR-deficient mutant provided the biosynthetic intermediate, unexpectedly harboring an acetyl group. In vitro assays showed that AclR alone promotes 1,2-sulfamyl migration, elimination of the acetoxy group, and spiroaminal formation. AclR features a thioredoxin oxidoreductase fold with a noncanonical CXXH motif that is distinct from the CXXC in the disulfide forming oxidase for the ETP biosynthesis. Crystallographic and mutational analyses of AclR revealed that the CXXH motif is crucial for catalysis, whereas the flavin-adenine dinucleotide is required as a support of the protein fold, and not as a redox cofactor. AclR proved to be a suitable bioinformatics handle to discover a number of related fungal gene clusters that potentially code for the biosynthesis of derailed ETP compounds. Our results highlight a specialized role of the thioredoxin oxidoreductase family enzyme in the ETP pathway and expand the chemical diversity of small molecules bearing an aberrant disulfide pharmacophore.
Subject(s)
Flavoproteins/metabolism , Mycotoxins/biosynthesis , Oxidoreductases Acting on Sulfur Group Donors/metabolism , Spiro Compounds/metabolism , Acetylation , Amino Acid Motifs , Aspergillus oryzae/enzymology , Aspergillus oryzae/genetics , Flavoproteins/genetics , Fungal Proteins/genetics , Fungal Proteins/metabolism , Genes, Fungal , Mutation , Mycotoxins/chemistry , Oxidation-Reduction , Oxidoreductases Acting on Sulfur Group Donors/genetics , Spiro Compounds/chemistryABSTRACT
Condensin I is a multi-protein complex that plays an essential role in mitotic chromosome assembly and segregation in eukaryotes. It is composed of five subunits: two SMC (SMC2 and SMC4), a kleisin (CAP-H), and two HEAT-repeat (CAP-D2 and CAP-G) subunits. Although balancing acts of the two HEAT-repeat subunits have been demonstrated to enable this complex to support the dynamic assembly of chromosomal axes in vertebrate cells, its underlying mechanisms remain poorly understood. Here, we report the crystal structure of a human condensin I subcomplex comprising hCAP-G and hCAP-H. hCAP-H binds to the concave surfaces of a harp-shaped HEAT-repeat domain of hCAP-G. Physical interaction between hCAP-G and hCAP-H is indeed essential for mitotic chromosome assembly recapitulated in Xenopus egg cell-free extracts. Furthermore, this study reveals that the human CAP-G-H subcomplex has the ability to interact with not only double-stranded DNA, but also single-stranded DNA, suggesting functional divergence of the vertebrate condensin I complex in proper mitotic chromosome assembly.
Subject(s)
Adenosine Triphosphatases/metabolism , DNA-Binding Proteins/metabolism , Multiprotein Complexes/metabolism , Nuclear Proteins/metabolism , Protein Subunits/metabolism , Amino Acid Sequence , Animals , Cell Cycle Proteins/metabolism , Chromosomal Proteins, Non-Histone/metabolism , Chromosome Segregation/physiology , Chromosomes/metabolism , DNA, Single-Stranded/metabolism , Humans , RNA, Double-Stranded/metabolism , Sequence Alignment , Xenopus laevis/metabolismABSTRACT
Biosynthesis of fungal nonribosomal peptides frequently involves redox enzymes such as flavin-containing monooxygenase (FMO) to introduce complexity into the core chemical structure. One such example is the formation of spiro-carbons catalyzed by various oxidases. Because many chemically complex spiro-carbon-bearing natural products exhibit useful biological activities, understanding the mechanism of spiro-carbon biosynthesis is of great interest. We previously identified FqzB, an FMO from the fumiquinazoline biosynthetic pathway responsible for epoxidation of fumiquinazoline F that crosstalks with the fumitremorgin biosynthetic pathway to form spirotryprostatin A via epoxidation of the precursor fumitremorgin C. What makes FqzB more interesting is its relaxed substrate specificity, where it can accept a range of other substrates, including tryprostatins A and B along with its original substrate fumiquinazoline F. Here, we characterized FqzB crystallographically and examined FqzB and its site-specific mutants kinetically to understand how this promiscuous epoxidase works. Furthermore, the mutagenesis studies as well as computational docking experiments between the FqzB crystal structure and its known substrates spirotryprostatin A and B, as well as fumitremorgin C and fumiquinazoline F, provided insight into potential modes of substrate recognition and the source of broad substrate tolerance exhibited by this epoxidase. This study serves as a foundation for further characterization and engineering of this redox enzyme, which has potential utility as a valuable catalyst with broad substrate tolerance and an ability to introduce chemical complexity into carbon frameworks for chemoenzymatic and biosynthetic applications.
Subject(s)
Biological Products/chemistry , Epoxy Compounds/chemistry , Fungal Proteins/chemistry , Mixed Function Oxygenases/chemistry , Spiro Compounds/chemistry , Amino Acid Sequence , Fungal Proteins/genetics , Fungi/enzymology , Kinetics , Mixed Function Oxygenases/genetics , Models, Chemical , Molecular Docking Simulation , Mutagenesis, Site-Directed , Mutation , Substrate SpecificityABSTRACT
Here, we managed to reconstruct a three-dimensional color video of a point-cloud object using a projection-type holographic display with a holographic optical element as an optical screen. The holographic optical element has the function of an off-axis concave mirror and has been created by the wavefront printer digitally. We defined and implemented an algorithm to reconstruct a three-dimensional image at a chosen position considering the specification of the holographic optical element designed digitally. We successfully demonstrated a reconstruction of the color video in question, composed of three-dimensional images through the holographic optical element.
ABSTRACT
Purpose: This study evaluated the usefulness of intraprocedural contrast-enhanced ultrasound (CEUS)/ultrasound (US) fusion imaging using a perflubutane-based contrast agent combined with preprocedural auto sweep three-dimensional US to obtain volume data for guidance and evaluation of the therapeutic efficacy of radiofrequency ablation (RFA).Methods: This uncontrolled clinical trial included 50 hepatocellular carcinomas (HCCs) with a mean diameter of 15.3 mm that had been treated by RFA. The efficacy of RFA was evaluated by CEUS/US fusion imaging during the procedure. If the ablation was deemed to be inadequate, further ablation was performed until adequate ablation was achieved. Contrast-enhanced computed tomography (CECT) or contrast-enhanced magnetic resonance imaging (CEMRI) was performed a month after RFA, and the images obtained using each modality were reviewed to evaluate the efficacy of RFA.Results: Thirty-three of the 50 lesions were evaluated by CEUS/US fusion imaging as having been adequately ablated after the first RFA procedure. The ablation was evaluated as inadequate in the remaining 17 lesions, for which additional ablation was performed. Ninety-eight (49/50) of all HCCs were evaluated as having been eventually adequately ablated on intraprocedural CEUS/US fusion imaging. The concordance rate for evaluations between intraprocedural CEUS/US fusion imaging and CECT/CEMRI performed 1 month after RFA was 88% (44/50). The kappa value for agreement between the two methods of evaluation was 0.792.Conclusion: Intraprocedural fusion imaging combining CEUS and auto sweep three-dimensional US appears to be a useful modality for RFA guidance and evaluation of therapeutic efficacy of RFA in patients with HCC.
Subject(s)
Carcinoma, Hepatocellular/surgery , Catheter Ablation/methods , Contrast Media/therapeutic use , Fluorocarbons/therapeutic use , Liver Neoplasms/surgery , Radiofrequency Ablation/methods , Ultrasonography/methods , Adult , Aged , Aged, 80 and over , Carcinoma, Hepatocellular/mortality , Female , Fluorocarbons/pharmacology , Humans , Liver Neoplasms/mortality , Middle Aged , Survival AnalysisABSTRACT
DNA-damage tolerance protects cells via at least two sub-pathways regulated by proliferating cell nuclear antigen (PCNA) ubiquitination in eukaryotes: translesion DNA synthesis (TLS) and template switching (TS), which are stimulated by mono- and polyubiquitination, respectively. However, how cells choose between the two pathways remains unclear. The regulation of ubiquitin ligases catalyzing polyubiquitination, such as helicase-like transcription factor (HLTF), could play a role in the choice of pathway. Here, we demonstrate that the ligase activity of HLTF is stimulated by double-stranded DNA via HIRAN domain-dependent recruitment to stalled primer ends. Replication factor C (RFC) and PCNA located at primer ends, however, suppress en bloc polyubiquitination in the complex, redirecting toward sequential chain elongation. When PCNA in the complex is monoubiquitinated by RAD6-RAD18, the resulting ubiquitin moiety is immediately polyubiquitinated by coexisting HLTF, indicating a coupling reaction between mono- and polyubiquitination. By contrast, when PCNA was monoubiquitinated in the absence of HLTF, it was not polyubiquitinated by subsequently recruited HLTF unless all three-subunits of PCNA were monoubiquitinated, indicating that the uncoupling reaction specifically occurs on three-subunit-monoubiquitinated PCNA. We discuss the physiological relevance of the different modes of the polyubiquitination to the choice of cells between TLS and TS under different conditions.
Subject(s)
DNA Repair , DNA-Binding Proteins/genetics , DNA/genetics , Proliferating Cell Nuclear Antigen/genetics , Protein Processing, Post-Translational , Replication Protein C/genetics , Transcription Factors/genetics , Amino Acid Sequence , Animals , DNA/metabolism , DNA Damage , DNA Primers/chemistry , DNA Primers/metabolism , DNA-Binding Proteins/metabolism , Humans , Polyubiquitin/genetics , Polyubiquitin/metabolism , Proliferating Cell Nuclear Antigen/metabolism , Protein Subunits/genetics , Protein Subunits/metabolism , Replication Protein C/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Signal Transduction , Transcription Factors/metabolism , Ubiquitin-Conjugating Enzymes/genetics , Ubiquitin-Conjugating Enzymes/metabolism , Ubiquitin-Protein Ligases/genetics , UbiquitinationABSTRACT
Biosynthesis of certain fungal polyketide-peptide synthetases involves C-methyltransferase activity that adds one or more S-adenosyl-l-methionine-derived methyl groups to the carbon framework. The previously reported PsoF-MT, the stand-alone C-methyltransferase (MT) from the pseurotin biosynthetic pathway that exists as a domain within a trifunctional didomain enzyme PsoF, was characterized crystallographically and kinetically using mutants with substrate analogs to understand how a trans-acting C-MT works and compare it to known polyketide synthase-associated C-MTs. This study identified key active-site residues involved in catalysis and substrate recognition, which led us to propose the mechanism of C-methylation and substrate specificity determinants in PsoF-MT.
Subject(s)
Aspergillus/enzymology , Fungal Proteins/metabolism , Methyltransferases/metabolism , Pyrrolidinones/metabolism , Biosynthetic Pathways , Catalytic Domain , Crystallography, X-Ray , Fungal Proteins/chemistry , Methylation , Methyltransferases/chemistry , Molecular Docking Simulation , Secondary Metabolism , Stereoisomerism , Substrate SpecificityABSTRACT
Three new compounds, namely, 4-(4'-hydroxy-3'-methoxyphenyl)-3,5,7-trihydroxycoumarin (1) and sulawesins A (2) and B (3), were isolated from the propolis of stingless bees ( Tetragonula aff. biroi) collected on South Sulawesi, Indonesia. In addition, five known compounds, glyasperin A, broussoflavonol F, (2 S)-5,7-dihydroxy-4'-methoxy-8-prenylflavanone, (1' S)-2- trans,4- trans-abscisic acid, and (1' S)-2- cis,4- trans-abscisic acid, were identified. The structures of the new compounds were determined by a combination of methods that included mass spectrometry and NMR spectroscopy. The absolute configuration of sulawesin A (2), a new podophyllotoxin derivative, was determined by X-ray crystallography. The absolute configuration of sulawesin B (3) was also determined by the ECD calculation. 4-(4'-Hydroxy-3'-methoxyphenyl)-3,5,7-trihydroxycoumarin (1) and sulawesin A (2) were examined for xanthine oxidase (XO) inhibitory activity; 1 exhibited XO inhibitory activity, with an IC50 value of 3.9 µM.
Subject(s)
Coumarins/isolation & purification , Propolis/analysis , Sesterterpenes/isolation & purification , Xanthine Oxidase/antagonists & inhibitors , Animals , Bees , Coumarins/chemistry , Coumarins/pharmacology , Indonesia , Molecular Structure , Sesterterpenes/chemistry , Sesterterpenes/pharmacologyABSTRACT
ADP-ribosyltransferases transfer the ADP-ribose moiety of ßNAD+ to an acceptor molecule, usually a protein that modulates the function of the acceptor. Pierisin-1 is an ADP-ribosyltransferase from the cabbage butterfly Pieris rapae and is composed of N-terminal catalytic and C-terminal ricin B-like domains. Curiously, it ADP-ribosylates the DNA duplex, resulting in apoptosis of various cancer cells, which has raised interest in pierisin-1 as an anti-cancer agent. However, both the structure and the mechanism of DNA ADP-ribosylation are unclear. Here, we report the crystal structures of the N-terminal catalytic domain of pierisin-1, its complex with ßNAD+, and the catalytic domain with the linker connecting it to the ricin B-like domains. We found that the catalytic domain possesses a defined, positively charged region on the molecular surface but that its overall structure is otherwise similar to those of protein-targeting ADP-ribosyltransferases. Electrophoretic mobility shift assays and site-directed mutagenesis indicated that pierisin-1 binds double-stranded but not single-stranded DNA and that Lys122, Lys123, and Lys124, which are found in a loop, and Arg181 and Arg187, located in a basic cleft near the loop, are required for DNA binding. Furthermore, the structure of the catalytic domain with the linker revealed an autoinhibitory mechanism in which the linker occupies and blocks both the ßNAD+- and DNA-binding sites, suggesting that proteolytic cleavage to remove the linker is necessary for enzyme catalysis. Our study provides a structural basis for the DNA-acceptor specificity of pierisin-1 and reveals that a self-regulatory mechanism is required for its activity.
Subject(s)
ADP Ribose Transferases/metabolism , Butterflies/enzymology , DNA/metabolism , Enzyme Precursors/metabolism , Insect Proteins/metabolism , Models, Molecular , NAD/metabolism , Protein Processing, Post-Translational , ADP Ribose Transferases/chemistry , ADP Ribose Transferases/genetics , Amino Acid Substitution , Animals , Binding Sites , Biocatalysis , Catalytic Domain , Crystallography, X-Ray , DNA/chemistry , Electrophoretic Mobility Shift Assay , Enzyme Activation , Enzyme Precursors/chemistry , Enzyme Precursors/genetics , Insect Proteins/chemistry , Insect Proteins/genetics , Mutagenesis, Site-Directed , Mutation , NAD/chemistry , Peptide Fragments/chemistry , Peptide Fragments/genetics , Peptide Fragments/metabolism , Protein Conformation , Protein Interaction Domains and Motifs , Proteolysis , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/metabolism , Structural Homology, ProteinABSTRACT
Mitotic arrest deficient 2-like protein 2 (MAD2L2), also termed MAD2B or REV7, is involved in multiple cellular functions including translesion DNA synthesis (TLS), signal transduction, transcription, and mitotic events. MAD2L2 interacts with chromosome alignment-maintaining phosphoprotein (CAMP), a kinetochore-microtubule attachment protein in mitotic cells, presumably through a novel "WK" motif in CAMP. Structures of MAD2L2 in complex with binding regions of the TLS proteins REV3 and REV1 have revealed that MAD2L2 has two faces for protein-protein interactions that are regulated by its C-terminal region; however, the mechanisms underlying the MAD2L2-CAMP interaction and the mitotic role of MAD2L2 remain unknown. Here we have determined the structures of human MAD2L2 in complex with a CAMP fragment in two crystal forms. The overall structure of the MAD2L2-CAMP complex in both crystal forms was essentially similar to that of the MAD2L2-REV3 complex. However, the residue interactions between MAD2L2 and CAMP were strikingly different from those in the MAD2L2-REV3 complex. Furthermore, structure-based interaction analyses revealed an unprecedented mechanism involving CAMP's WK motif. Surprisingly, in one of the crystal forms, the MAD2L2-CAMP complex formed a dimeric structure in which the C-terminal region of MAD2L2 was swapped and adopted an immature structure. The structure provides direct evidence for the dynamic nature of MAD2L2 structure, which in turn may have implications for the protein-protein interaction mechanism and the multiple functions of this protein. This work is the first structural study of MAD2L2 aside from its role in TLS and might pave the way to clarify MAD2L2's function in mitosis.
Subject(s)
Cell Cycle Checkpoints/physiology , Chromosomal Proteins, Non-Histone , Mad2 Proteins , Multiprotein Complexes , Phosphoproteins , Amino Acid Motifs , Chromosomal Proteins, Non-Histone/chemistry , Chromosomal Proteins, Non-Histone/genetics , Chromosomal Proteins, Non-Histone/metabolism , Crystallography, X-Ray , HeLa Cells , Humans , Mad2 Proteins/chemistry , Mad2 Proteins/genetics , Mad2 Proteins/metabolism , Multiprotein Complexes/chemistry , Multiprotein Complexes/genetics , Multiprotein Complexes/metabolism , Phosphoproteins/chemistry , Phosphoproteins/genetics , Phosphoproteins/metabolism , Protein Domains , Protein Structure, Quaternary , Structure-Activity RelationshipABSTRACT
ETS proto-oncogene 1, transcription factor (ETS1) is involved in various immune responses. Genome-wide association studies on systemic lupus erythematosus in Chinese populations identified the association of ETS1 polymorphism in 3' untranslated region, rs1128334A, which was associated with lower ETS1 expression. In view of substantial sharing of susceptibility genes across multiple autoimmune diseases, we examined whether ETS1 is associated with a rare autoimmune rheumatic disease, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Association of rs1128334 was tested in 466 Japanese patients with AAV and 1099 healthy controls by logistic regression analysis under the additive model. AAV patients were classified into 285 microscopic polyangiitis (MPA), 92 granulomatosis with polyangiitis (GPA), 56 eosinophilic GPA, and 33 unclassifiable AAV, according to the European Medicines Agency (EMEA) algorithm. Among the patients, 376 were positive for MPO-ANCA and 62 for PR3-ANCA. When the patients were classified according to the EMEA classification, rs1128334A allele was significantly increased in GPA (P = 0.0060, P c = 0.030, odds ratio (OR), 1.54; 95% confidence interval (CI), 1.13-2.10). With respect to the ANCA specificity, significant association was observed in PR3-ANCA positive AAV (P = 0.0042, P c = 0.021, OR, 1.72; 95% CI, 1.19-2.49). In conclusion, ETS1 polymorphism was suggested to be associated with GPA and PR3-ANCA positive AAV in a Japanese population.
Subject(s)
3' Untranslated Regions , Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis/genetics , Granulomatosis with Polyangiitis/genetics , Polymorphism, Genetic , Proto-Oncogene Protein c-ets-1/genetics , Asian People , Female , Humans , Japan , Male , Proto-Oncogene MasABSTRACT
A 40-year-old male was referred to our hospital because of a nodular shadow detected in the left lower lobe with the tendency to increase gently. Because fluoro-2-deoxy-D-glucose (FDG) uptake was extremely low on a FDG positron emission tomography (PET-CT), the tumor was highly suspected of the benign tumor. Five years later, a follow-up computed tomography (CT) showed the shadow to be enlarged. FDG uptake was changed to be high, and serum level of pro-gastrin-releasing peptide (Pro-GRP) was extremely elevated. Surgical treatment was chosen under suspicious diagnosis of neuroendocrine tumor, such as small cell carcinoma, large cell neuroendocrine carcinoma, and carcinoid. By the intraoperative aspiration cytology, a small cell carcinoma or a carcinoid was suspected and left lower lobectomy with systemic lymph node dissection was performed. The final histological diagnosis was a typical carcinoid. The elevated serum ProGRP immediately decreased to normal postoperatively.