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Kim S, Chang JH. Structural Analysis of Spermidine Synthase from Kluyveromyces lactis. Molecules 2023; 28:molecules28083446. [PMID: 37110680 PMCID: PMC10146546 DOI: 10.3390/molecules28083446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/07/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
Spermidine is a polyamine molecule that performs various cellular functions, such as DNA and RNA stabilization, autophagy modulation, and eIF5A formation, and is generated from putrescine by aminopropyltransferase spermidine synthase (SpdS). During synthesis, the aminopropyl moiety is donated from decarboxylated S-adenosylmethionine to form putrescine, with 5'-deoxy-5'-methylthioadenosine being produced as a byproduct. Although the molecular mechanism of SpdS function has been well-established, its structure-based evolutionary relationships remain to be fully understood. Moreover, only a few structural studies have been conducted on SpdS from fungal species. Here, we determined the crystal structure of an apo-form of SpdS from Kluyveromyces lactis (KlSpdS) at 1.9 Å resolution. Structural comparison with its homologs revealed a conformational change in the α6 helix linked to the gate-keeping loop, with approximately 40° outward rotation. This change caused the catalytic residue Asp170 to move outward, possibly due to the absence of a ligand in the active site. These findings improve our understanding of the structural diversity of SpdS and provide a missing link that expands our knowledge of the structural features of SpdS in fungal species.
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Affiliation(s)
- Seongjin Kim
- Department of Biology Education, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
| | - Jeong Ho Chang
- Department of Biology Education, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
- Department of Biomedical Convergence Science and Technology, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
- Science Education Research Institute, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
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2
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Jang J, Chang JH. Molecular Structure of Phosphoserine Aminotransferase from Saccharomyces cerevisiae. Int J Mol Sci 2023; 24:ijms24065139. [PMID: 36982214 PMCID: PMC10049462 DOI: 10.3390/ijms24065139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 03/10/2023] Open
Abstract
Phosphoserine aminotransferase (PSAT) is a pyridoxal 5′-phosphate-dependent enzyme involved in the second step of the phosphorylated pathway of serine biosynthesis. PSAT catalyzes the transamination of 3-phosphohydroxypyruvate to 3-phosphoserine using L-glutamate as the amino donor. Although structural studies of PSAT have been performed from archaea and humans, no structural information is available from fungi. Therefore, to elucidate the structural features of fungal PSAT, we determined the crystal structure of Saccharomyces cerevisiae PSAT (ScPSAT) at a resolution of 2.8 Å. The results demonstrated that the ScPSAT protein was dimeric in its crystal structure. Moreover, the gate-keeping loop of ScPSAT exhibited a conformation similar to that of other species. Several distinct structural features in the halide-binding and active sites of ScPSAT were compared with its homologs. Overall, this study contributes to our current understanding of PSAT by identifying the structural features of fungal PSAT for the first time.
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Affiliation(s)
- Jiyeon Jang
- Department of Biology Education, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
| | - Jeong Ho Chang
- Department of Biology Education, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
- Department of Biomedical Convergence Science and Technology, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
- Correspondence: ; Tel.: +82-53-950-5913; Fax: +82-53-950-6809
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Xiang L, Piao L, Wang D, Qi LFR. Overexpression of SMS in the tumor microenvironment is associated with immunosuppression in hepatocellular carcinoma. Front Immunol 2022; 13:974241. [PMID: 36544774 PMCID: PMC9760682 DOI: 10.3389/fimmu.2022.974241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 11/02/2022] [Indexed: 12/12/2022] Open
Abstract
Disorders of polyamine metabolism may contribute to the development of hepatocellular carcinoma (HCC), but the precise mechanism remains unknown. This study reports that spermine synthase (SMS), an enzyme involved in polyamine biosynthesis, is overexpressed in HCC and not associated with hepatitis virus infection in HCC patients. The results of analyzing the clinical data of HCC patients showed that SMS level as a categorical dependent variable was related to clinicopathological features of poor prognosis. Furthermore, the Kaplan-Meier survival analysis and ROC curve indicated that increased SMS level is associated with poor survival rate in HCC and may be a potential biomarker to discriminate HCC tissues. However, SMS overexpression limited the therapeutic effect of immune checkpoint blockade (ICB), which seemed to be related to the immunosuppressive effect of the HCC immune microenvironment formed by higher mRNA transcript levels of immune checkpoints and higher infiltration levels of immunosuppressive cells. In samples with high and low SMS expression, functional enrichment analysis of the differentially expressed genes (DEGs) showed that SMS may be linked to the occurrence and development of HCC by affecting a variety of immune-related pathways, such as Intestinal immune network for IgA production, Fc gamma R-mediated phagocytosis, Antigen processing and presentation, Th1 and Th2 cell differentiation. Subsequently, analysis of the co-expression network of SMS in the liver hepatocellular carcinoma (LIHC) cohort revealed that SMS has a broad impact on multiple important immune- and metabolic-related processes in HCC. In summary, SMS is a promising biomarker to differentiate the prognosis, immune characteristics, and holds promise as a potential target for ICB therapy to improve HCC.
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Affiliation(s)
- Lin Xiang
- Department of Translational Medicine Research Institute, Jiangsu Yifengrong Biotechnology Co., Ltd., Nanjing, Jiangsu, China
| | - Longhuan Piao
- Department of Orthopedic Surgery, Shengjing Hospital of China Medical University, Shenyang, Liaoning, China
| | - Dong Wang
- Department of Histology and Embryology, Binzhou Medical University, Yantai, Shandong, China
| | - Li-Feng-Rong Qi
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, Jiangsu, China,*Correspondence: Li-Feng-Rong Qi,
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Guo Y, Ye Q, Deng P, Cao Y, He D, Zhou Z, Wang C, Zaytseva YY, Schwartz CE, Lee EY, Evers BM, Morris AJ, Liu S, She QB. Spermine synthase and MYC cooperate to maintain colorectal cancer cell survival by repressing Bim expression. Nat Commun 2020; 11:3243. [PMID: 32591507 PMCID: PMC7320137 DOI: 10.1038/s41467-020-17067-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 06/08/2020] [Indexed: 12/13/2022] Open
Abstract
Dysregulation of polyamine metabolism has been linked to the development of colorectal cancer (CRC), but the underlying mechanism is incompletely characterized. Here, we report that spermine synthase (SMS), a polyamine biosynthetic enzyme, is overexpressed in CRC. Targeted disruption of SMS in CRC cells results in spermidine accumulation, which inhibits FOXO3a acetylation and allows subsequent translocation to the nucleus to transcriptionally induce expression of the proapoptotic protein Bim. However, this induction is blunted by MYC-driven expression of miR-19a and miR-19b that repress Bim production. Pharmacological or genetic inhibition of MYC activity in SMS-depleted CRC cells dramatically induces Bim expression and apoptosis and causes tumor regression, but these effects are profoundly attenuated by silencing Bim. These findings uncover a key survival signal in CRC through convergent repression of Bim expression by distinct SMS- and MYC-mediated signaling pathways. Thus, combined inhibition of SMS and MYC signaling may be an effective therapy for CRC. Polyamine metabolism is frequently dysregulated in cancers. Here, the authors show that a polyamine biosynthetic enzyme, spermine synthase, is overexpressed in colorectal cancers and cooperates with MYC to prevent cancer cell apoptosis by repression of proapoptotic protein, Bim.
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Affiliation(s)
- Yubin Guo
- Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, 510515, Guangzhou, China.,Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Qing Ye
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA.,Department of Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Pan Deng
- Superfund Research Center, University of Kentucky, Lexington, KY, 40536, USA
| | - Yanan Cao
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA.,Department of Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Daheng He
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Zhaohe Zhou
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Chi Wang
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA.,Department of Biostatistics, University of Kentucky College of Public Health, Lexington, KY, 40506, USA
| | - Yekaterina Y Zaytseva
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA.,Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | | | - Eun Y Lee
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA.,Department of Pathology and Laboratory Medicine, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - B Mark Evers
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA.,Department of Surgery, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Andrew J Morris
- Division of Cardiovascular Medicine and the Gill Heart Institute, University of Kentucky College of Medicine, and Lexington Veterans Affairs Medical Center, Lexington, KY, 40506, USA
| | - Side Liu
- Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, 510515, Guangzhou, China.
| | - Qing-Bai She
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA. .,Department of Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, KY, 40506, USA.
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Half Way to Hypusine-Structural Basis for Substrate Recognition by Human Deoxyhypusine Synthase. Biomolecules 2020; 10:biom10040522. [PMID: 32235505 PMCID: PMC7226451 DOI: 10.3390/biom10040522] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/23/2020] [Accepted: 03/26/2020] [Indexed: 02/08/2023] Open
Abstract
Deoxyhypusine synthase (DHS) is a transferase enabling the formation of deoxyhypusine, which is the first, rate-limiting step of a unique post-translational modification: hypusination. DHS catalyses the transfer of a 4-aminobutyl moiety of polyamine spermidine to a specific lysine of eukaryotic translation factor 5A (eIF5A) precursor in a nicotinamide adenine dinucleotide (NAD)-dependent manner. This modification occurs exclusively on one protein, eIF5A, and it is essential for cell proliferation. Malfunctions of the hypusination pathway, including those caused by mutations within the DHS encoding gene, are associated with conditions such as cancer or neurodegeneration. Here, we present a series of high-resolution crystal structures of human DHS. Structures were determined as the apoprotein, as well as ligand-bound states at high-resolutions ranging from 1.41 to 1.69 Å. By solving DHS in complex with its natural substrate spermidine (SPD), we identified the mode of substrate recognition. We also observed that other polyamines, namely spermine (SPM) and putrescine, bind DHS in a similar manner as SPD. Moreover, we performed activity assays showing that SPM could to some extent serve as an alternative DHS substrate. In contrast to previous studies, we demonstrate that no conformational changes occur in the DHS structure upon spermidine-binding. By combining mutagenesis and a light-scattering approach, we show that a conserved “ball-and-chain” motif is indispensable to assembling a functional DHS tetramer. Our study substantially advances our knowledge of the substrate recognition mechanism by DHS and may aid the design of pharmacological compounds for potential applications in cancer therapy.
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Crystal structure of dimeric Synechococcus spermidine synthase with bound polyamine substrate and product. Biochem J 2019; 476:1009-1020. [DOI: 10.1042/bcj20180811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/05/2019] [Accepted: 03/14/2019] [Indexed: 11/17/2022]
Abstract
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.
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Abstract
In trypanosomatids, polyamine and trypanothione pathways can be considered as a whole unique metabolism, where most enzymes are essential for parasitic survival and infectivity. Leishmania parasites and all the other members of the Trypanosomatids family depend on polyamines for growth and survival: the enzymes involved in the synthesis and utilization of spermidine and trypanothione, i.e., arginase, ornithine decarboxylase, S-adenosylmethionine decarboxylase, spermidine synthase and in particular trypanothione synthetase-amidase, trypanothione reductase and tryparedoxin-dependent peroxidase are promising targets for drug development. This review deals with recent structure-based studies on these enzymes, aimed at the discovery of inhibitors of this pathway.
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Sprenger J, Carey J, Svensson B, Wengel V, Persson L. Binding and Inhibition of Spermidine Synthase from Plasmodium falciparum and Implications for In Vitro Inhibitor Testing. PLoS One 2016; 11:e0163442. [PMID: 27661085 PMCID: PMC5035006 DOI: 10.1371/journal.pone.0163442] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 09/08/2016] [Indexed: 11/23/2022] Open
Abstract
The aminopropyltransferase spermidine synthase (SpdS) is a promising drug target in cancer and in protozoan diseases including malaria. Plasmodium falciparum SpdS (PfSpdS) transfers the aminopropyl group of decarboxylated S-adenosylmethionine (dcAdoMet) to putrescine or to spermidine to form spermidine or spermine, respectively. In an effort to understand why efficient inhibitors of PfSpdS have been elusive, the present study uses enzyme activity assays and isothermal titration calorimetry with verified or predicted inhibitors of PfSpdS to analyze the relationship between binding affinity as assessed by KD and inhibitory activity as assessed by IC50. The results show that some predicted inhibitors bind to the enzyme with high affinity but are poor inhibitors. Binding studies with PfSpdS substrates and products strongly support an ordered sequential mechanism in which the aminopropyl donor (dcAdoMet) site must be occupied before the aminopropyl acceptor (putrescine) site can be occupied. Analysis of the results also shows that the ordered sequential mechanism adequately accounts for the complex relationship between IC50 and KD and may explain the limited success of previous efforts at structure-based inhibitor design for PfSpdS. Based on PfSpdS active-site occupancy, we suggest a classification of ligands that can help to predict the KD−IC50 relations in future design of new inhibitors. The present findings may be relevant for other drug targets that follow an ordered sequential mechanism.
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Affiliation(s)
- Janina Sprenger
- Center for Molecular Protein Science, Lund University, SE-221 00, Lund, Sweden
- Department of Experimental Medical Science, Lund University, SE-221 84, Lund, Sweden
| | - Jannette Carey
- Chemistry Department, Princeton University, Princeton, New Jersey, 08544, United States of America
| | - Bo Svensson
- SARomics Biostructures AB, Medicon Village, SE-223 81, Lund, Sweden
| | - Verena Wengel
- Center for Molecular Protein Science, Lund University, SE-221 00, Lund, Sweden
- Department of Experimental Medical Science, Lund University, SE-221 84, Lund, Sweden
| | - Lo Persson
- Department of Experimental Medical Science, Lund University, SE-221 84, Lund, Sweden
- * E-mail:
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Sprenger J, Svensson B, Hålander J, Carey J, Persson L, Al-Karadaghi S. Three-dimensional structures of Plasmodium falciparum spermidine synthase with bound inhibitors suggest new strategies for drug design. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:484-93. [PMID: 25760598 PMCID: PMC4356361 DOI: 10.1107/s1399004714027011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 12/09/2014] [Indexed: 01/06/2023]
Abstract
The enzymes of the polyamine-biosynthesis pathway have been proposed to be promising drug targets in the treatment of malaria. Spermidine synthase (SpdS; putrescine aminopropyltransferase) catalyzes the transfer of the aminopropyl moiety from decarboxylated S-adenosylmethionine to putrescine, leading to the formation of spermidine and 5'-methylthioadenosine (MTA). In this work, X-ray crystallography was used to examine ligand complexes of SpdS from the malaria parasite Plasmodium falciparum (PfSpdS). Five crystal structures were determined of PfSpdS in complex with MTA and the substrate putrescine, with MTA and spermidine, which was obtained as a result of the enzymatic reaction taking place within the crystals, with dcAdoMet and the inhibitor 4-methylaniline, with MTA and 4-aminomethylaniline, and with a compound predicted in earlier in silico screening to bind to the active site of the enzyme, benzimidazol-(2-yl)pentan-1-amine (BIPA). In contrast to the other inhibitors tested, the complex with BIPA was obtained without any ligand bound to the dcAdoMet-binding site of the enzyme. The complexes with the aniline compounds and BIPA revealed a new mode of ligand binding to PfSpdS. The observed binding mode of the ligands, and the interplay between the two substrate-binding sites and the flexible gatekeeper loop, can be used in the design of new approaches in the search for new inhibitors of SpdS.
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Affiliation(s)
- Janina Sprenger
- Center for Molecular Protein Science, Lund University, SE-221 00 Lund, Sweden
- Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden
| | - Bo Svensson
- Center for Molecular Protein Science, Lund University, SE-221 00 Lund, Sweden
- SARomics Biostructures AB, Box 724, SE-220 07 Lund, Sweden
| | - Jenny Hålander
- Center for Molecular Protein Science, Lund University, SE-221 00 Lund, Sweden
| | - Jannette Carey
- Chemistry Department, Princeton University, Princeton, New Jersey, USA
| | - Lo Persson
- Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden
| | - Salam Al-Karadaghi
- Center for Molecular Protein Science, Lund University, SE-221 00 Lund, Sweden
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