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Schlaak L, Weise C, Kuropka B, Weng A. Mutational Analysis of RIP Type I Dianthin-30 Suggests a Role for Arg24 in Endocytosis. Toxins (Basel) 2024; 16:219. [PMID: 38787071 PMCID: PMC11125672 DOI: 10.3390/toxins16050219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/30/2024] [Accepted: 05/07/2024] [Indexed: 05/25/2024] Open
Abstract
Saponin-mediated endosomal escape is a mechanism that increases the cytotoxicity of type I ribosome-inactivating proteins (type I RIPs). In order to actualize their cytotoxicity, type I RIPs must be released into the cytosol after endocytosis. Without release from the endosomes, type I RIPs are largely degraded and cannot exert their cytotoxic effects. Certain triterpene saponins are able to induce the endosomal escape of these type I RIPs, thus increasing their cytotoxicity. However, the molecular mechanism underlying the endosomal escape enhancement of type I RIPs by triterpene saponins has not been fully elucidated. In this report, we investigate the involvement of the basic amino acid residues of dianthin-30, a type I RIP isolated from the plant Dianthus caryophyllus L., in endosomal escape enhancement using alanine scanning. Therefore, we designed 19 alanine mutants of dianthin-30. Each mutant was combined with SO1861, a triterpene saponin isolated from the roots of Saponaria officinalis L., and subjected to a cytotoxicity screening in Neuro-2A cells. Cytotoxic screening revealed that dianthin-30 mutants with lysine substitutions did not impair the endosomal escape enhancement. There was one particular mutant dianthin, Arg24Ala, that exhibited significantly reduced synergistic cytotoxicity in three mammalian cell lines. However, this reduction was not based on an altered interaction with SO1861. It was, rather, due to the impaired endocytosis of dianthin Arg24Ala into the cells.
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Affiliation(s)
- Louisa Schlaak
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195 Berlin, Germany;
| | - Christoph Weise
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany; (C.W.); (B.K.)
| | - Benno Kuropka
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany; (C.W.); (B.K.)
| | - Alexander Weng
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195 Berlin, Germany;
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Sabale PM, Srivatsan SG. Responsive Fluorescent PNA Analogue as a Tool for Detecting G-quadruplex Motifs of Oncogenes and Activity of Toxic Ribosome-Inactivating Proteins. Chembiochem 2016; 17:1665-73. [PMID: 27271025 DOI: 10.1002/cbic.201600192] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Indexed: 12/13/2022]
Abstract
Fluorescent oligomers that are resistant to enzymatic degradation and report their binding to target oligonucleotides (ONs) by changes in fluorescence properties are highly useful in developing nucleic-acid-based diagnostic tools and therapeutic strategies. Here, we describe the synthesis and photophysical characterization of fluorescent peptide nucleic acid (PNA) building blocks made of microenvironment-sensitive 5-(benzofuran-2-yl)- and 5-(benzothiophen-2-yl)-uracil cores. The emissive monomers, when incorporated into PNA oligomers and hybridized to complementary ONs, are minimally perturbing and are highly sensitive to their neighboring base environment. In particular, benzothiophene-modified PNA reports the hybridization process with significant enhancement in fluorescence intensity, even when placed in the vicinity of guanine residues, which often quench fluorescence. This feature was used in the turn-on detection of G-quadruplex-forming promoter DNA sequences of human proto-oncogenes (c-myc and c-kit). Furthermore, the ability of benzothiophene-modified PNA oligomer to report the presence of an abasic site in RNA enabled us to develop a simple fluorescence hybridization assay to detect and estimate the depurination activity of ribosome-inactivating protein toxins. Our results demonstrate that this approach with responsive PNA probes will provide new opportunities to develop robust tools to study nucleic acids.
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Affiliation(s)
- Pramod M Sabale
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Seergazhi G Srivatsan
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.
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Yuan H, Du Q, Sturm MB, Schramm VL. Soapwort Saporin L3 Expression in Yeast, Mutagenesis, and RNA Substrate Specificity. Biochemistry 2015; 54:4565-74. [PMID: 26091305 DOI: 10.1021/acs.biochem.5b00405] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Saporin L3 from Saponaria officinalis (soapwort) leaves is a type 1 ribosome-inactivating protein. It catalyzes the hydrolysis of oligonucleotide adenylate N-ribosidic bonds to release adenine from rRNA. Depurination sites include both adenines in the GAGA tetraloop of short sarcin-ricin stem-loops and multiple adenines within eukaryotic rRNA, tRNAs, and mRNAs. Multiple Escherichia coli vector designs for saporin L3 expression were attempted but demonstrated high toxicity even during plasmid maintenance and selection in E. coli nonexpression strains. Saporin L3 is >10(3) times more efficient at RNA deadenylation on short GAGA stem-loops than saporin S6, the saporin isoform currently used in immunotoxin clinical trials. We engineered a construct for the His-tagged saporin L3 to test for expression in Pichia pastoris when it is linked to the protein export system for the yeast α-mating factor. DNA encoding saporin L3 was cloned into a pPICZαB expression vector and expressed in P. pastoris under the alcohol dehydrogenase AOX1 promoter. A fusion protein of saporin L3 containing the pre-pro-sequence of the α-mating factor, the c-myc epitope, and the His tag was excreted from the P. pastoris cells and isolated from the culture medium. Autoprocessing of the α-mating factor yielded truncated saporin L3 (amino acids 22-280), the c-myc epitope, and the His tag expressed optimally as a 32 kDa construct following methanol induction. Saporin L3 was also expressed with specific alanines and/or serines mutated to cysteine. Native and Cys mutant saporins are kinetically similar. The recombinant expression of saporin L3 and its mutants permits the production and investigation of this high-activity ribosome-inactivating protein.
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Affiliation(s)
- Hongling Yuan
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Quan Du
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Matthew B Sturm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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Schrot J, Weng A, Melzig MF. Ribosome-inactivating and related proteins. Toxins (Basel) 2015; 7:1556-615. [PMID: 26008228 PMCID: PMC4448163 DOI: 10.3390/toxins7051556] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 04/23/2015] [Accepted: 04/28/2015] [Indexed: 01/15/2023] Open
Abstract
Ribosome-inactivating proteins (RIPs) are toxins that act as N-glycosidases (EC 3.2.2.22). They are mainly produced by plants and classified as type 1 RIPs and type 2 RIPs. There are also RIPs and RIP related proteins that cannot be grouped into the classical type 1 and type 2 RIPs because of their different sizes, structures or functions. In addition, there is still not a uniform nomenclature or classification existing for RIPs. In this review, we give the current status of all known plant RIPs and we make a suggestion about how to unify those RIPs and RIP related proteins that cannot be classified as type 1 or type 2 RIPs.
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Affiliation(s)
- Joachim Schrot
- Institute of Pharmacy, Freie Universitaet Berlin, Koenigin-Luise-Str. 2 + 4, 14195 Berlin, Germany.
| | - Alexander Weng
- Institute of Pharmacy, Freie Universitaet Berlin, Koenigin-Luise-Str. 2 + 4, 14195 Berlin, Germany.
| | - Matthias F Melzig
- Institute of Pharmacy, Freie Universitaet Berlin, Koenigin-Luise-Str. 2 + 4, 14195 Berlin, Germany.
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Saporin-S6: a useful tool in cancer therapy. Toxins (Basel) 2013; 5:1698-722. [PMID: 24105401 PMCID: PMC3813907 DOI: 10.3390/toxins5101698] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 09/17/2013] [Accepted: 09/22/2013] [Indexed: 01/24/2023] Open
Abstract
Thirty years ago, the type 1 ribosome-inactivating protein (RIP) saporin-S6 (also known as saporin) was isolated from Saponaria officinalis L. seeds. Since then, the properties and mechanisms of action of saporin-S6 have been well characterized, and it has been widely employed in the construction of conjugates and immunotoxins for different purposes. These immunotoxins have shown many interesting results when used in cancer therapy, particularly in hematological tumors. The high enzymatic activity, stability and resistance to conjugation procedures and blood proteases make saporin-S6 a very useful tool in cancer therapy. High efficacy has been reported in clinical trials with saporin-S6-containing immunotoxins, at dosages that induced only mild and transient side effects, which were mainly fever, myalgias, hepatotoxicity, thrombocytopenia and vascular leak syndrome. Moreover, saporin-S6 triggers multiple cell death pathways, rendering impossible the selection of RIP-resistant mutants. In this review, some aspects of saporin-S6, such as the chemico-physical characteristics, the structural properties, its endocytosis, its intracellular routing and the pathogenetic mechanisms of the cell damage, are reported. In addition, the recent progress and developments of saporin-S6-containing immunotoxins in cancer immunotherapy are summarized, including in vitro and in vivo pre-clinical studies and clinical trials.
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Tanpure AA, Pawar MG, Srivatsan SG. Fluorescent Nucleoside Analogs: Probes for Investigating Nucleic Acid Structure and Function. Isr J Chem 2013. [DOI: 10.1002/ijch.201300010] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Tanpure AA, Srivatsan SG. Synthesis and photophysical characterisation of a fluorescent nucleoside analogue that signals the presence of an abasic site in RNA. Chembiochem 2012; 13:2392-9. [PMID: 23070860 DOI: 10.1002/cbic.201200408] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Indexed: 11/07/2022]
Abstract
The synthesis and site-specific incorporation of an environment-sensitive fluorescent nucleoside analogue (2), based on a 5-(benzofuran-2-yl)pyrimidine core, into DNA oligonucleotides (ONs), and its photophysical properties within these ONs are described. Interestingly and unlike 2-aminopurine (a widely used nucleoside analogue probe), when incorporated into an ON and hybridised with a complementary ON, the emissive nucleoside 2 displays significantly higher emission intensity than the free nucleoside. Furthermore, photophysical characterisation shows that the fluorescence properties of the nucleoside analogue within ONs are significantly influenced by flanking bases, especially by guanosine. By utilising the responsiveness of the nucleoside to changes in base environment, a DNA ON reporter labelled with the emissive nucleoside 2 was constructed; this signalled the presence of an abasic site in a model depurinated sarcin/ricin RNA motif of a eukaryotic 28S rRNA.
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Affiliation(s)
- Arun A Tanpure
- Department of Chemistry, Indian Institute of Science Education and Research, 900, NCL Innovation Park, Dr. Homi Bhabha Road, Pune 411008, India
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Das MK, Sharma RS, Mishra V. Induction of apoptosis by ribosome inactivating proteins: importance of N-glycosidase activity. Appl Biochem Biotechnol 2012; 166:1552-61. [PMID: 22262020 DOI: 10.1007/s12010-012-9550-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 01/05/2012] [Indexed: 11/26/2022]
Abstract
Apoptotic cell death is a fundamental process in the development and physiological homeostasis of multicellular organisms. It is associated with control of cell numbers in tissues and organs during development, with cell turnover, and with response to infection. Molecules that trigger this process in continuously proliferating cancer cells can be used as chemotherapeutic agents. Ribosome inactivating proteins (RIPs) that inhibit translation in a cell by depurinating (N-glycosidase activity) the 28S rRNA are known to serve as apoptosis inducers. However, the role of depurination activity of the RIPs in apoptosis induction is still controversial. Presently, there are three different hypotheses which propose that depurination is: (1) essential, (2) essential but not the sole factor, or (3) not essential for apoptosis induction. This article reviews various experimental outcomes on the importance of N-glycosidase activity of RIPs in the induction of apoptosis.
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Affiliation(s)
- Mrinal Kumar Das
- Department of Environmental Studies, Laboratory of Bioresources & Environmental Biotechnology, University of Delhi, Delhi, -110 007, India
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Tanpure AA, Patheja P, Srivatsan SG. Label-free fluorescence detection of the depurination activity of ribosome inactivating protein toxins. Chem Commun (Camb) 2012; 48:501-3. [DOI: 10.1039/c1cc16667k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Lombardi A, Marshall RS, Savino C, Fabbrini MS, Ceriotti A. Type I Ribosome-Inactivating Proteins from Saponaria officinalis. TOXIC PLANT PROTEINS 2010. [DOI: 10.1007/978-3-642-12176-0_4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Ruggiero A, Di Maro A, Severino V, Chambery A, Berisio R. Crystal structure of PD-L1, a ribosome inactivating protein fromPhytolacca dioicaL. Leaves with the property to induce DNA cleavage. Biopolymers 2009; 91:1135-42. [DOI: 10.1002/bip.21260] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Lombardi A, Bursomanno S, Lopardo T, Traini R, Colombatti M, Ippoliti R, Flavell DJ, Flavell SU, Ceriotti A, Fabbrini MS. Pichia pastoris as a host for secretion of toxic saporin chimeras. FASEB J 2009; 24:253-65. [PMID: 19786581 DOI: 10.1096/fj.08-118042] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Most of the targeting moieties, such as antibody fragments or growth factor domains, used to construct targeted toxins for anticancer therapy derive from secretory proteins. These normally fold in the oxidative environment of the endoplasmic reticulum, and hence their folding in bacterial cells can be quite inefficient. For instance, only low amounts of properly folded antimetastatic chimera constituted by the amino-terminal fragment of human urokinase (ATF) fused to the plant ribosome-inactivating protein saporin could be recovered. ATF-saporin was instead secreted efficiently when expressed in eukaryotic cells protected from autointoxication with neutralizing anti-saporin antibodies. Pichia pastoris is a microbial eukaryotic host where these domains can fold into a transport-competent conformation and reach the extracellular medium. We show here that despite some host toxicity codon-usage optimization greatly increased the expression levels of active saporin but not those of an active-site mutant SAP-KQ in GS115 (his4) strain. The lack of any toxicity associated with expression of the latter confirmed that toxicity is due to saporin catalytic activity. Nevertheless, GS115 (his4) cells in flask culture secreted 3.5 mg/L of a histidine-tagged ATF-saporin chimera showing an IC(50) of 6 x 10(-11) M against U937 cells, thus demonstrating the suitability of this expression platform for secretion of toxic saporin-based chimeras.
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Affiliation(s)
- Alessio Lombardi
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, via Bassini 15, Milan, Italy
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Sikriwal D, Ghosh P, Batra JK. Ribosome inactivating protein saporin induces apoptosis through mitochondrial cascade, independent of translation inhibition. Int J Biochem Cell Biol 2008; 40:2880-8. [DOI: 10.1016/j.biocel.2008.06.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 05/29/2008] [Accepted: 06/12/2008] [Indexed: 10/21/2022]
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