bims-polyam 2023-02-26 papers

Issue of 2023–02–26
five papers selected by
Sebastian J. Hofer, University of Graz

Proc Natl Acad Sci U S A. 2023 Feb 28. 120(9): e2214165120

Functional polyamine metabolic enzymes and pathways encoded by the virosphere.

Bin Li, Jue Liang, Hamid R Baniasadi, Margaret A Phillips, Anthony J Michael.

Viruses produce more viruses by manipulating the metabolic and replication systems of their host cells. Many have acquired metabolic genes from ancestral hosts and use the encoded enzymes to subvert host metabolism. The polyamine spermidine is required for bacteriophage and eukaryotic virus replication, and herein, we have identified and functionally characterized diverse phage- and virus-encoded polyamine metabolic enzymes and pathways. These include pyridoxal 5'-phosphate (PLP)-dependent ornithine decarboxylase (ODC), pyruvoyl-dependent ODC and arginine decarboxylase (ADC), arginase, S-adenosylmethionine decarboxylase (AdoMetDC/speD), spermidine synthase, homospermidine synthase, spermidine N-acetyltransferase, and N-acetylspermidine amidohydrolase. We identified homologs of the spermidine-modified translation factor eIF5a encoded by giant viruses of the Imitervirales. Although AdoMetDC/speD is prevalent among marine phages, some homologs have lost AdoMetDC activity and have evolved into pyruvoyl-dependent ADC or ODC. The pelagiphages that encode the pyruvoyl-dependent ADCs infect the abundant ocean bacterium Candidatus Pelagibacter ubique, which we have found encodes a PLP-dependent ODC homolog that has evolved into an ADC, indicating that infected cells would contain both PLP- and pyruvoyl-dependent ADCs. Complete or partial spermidine or homospermidine biosynthetic pathways are found encoded in the giant viruses of the Algavirales and Imitervirales, and in addition, some viruses of the Imitervirales can release spermidine from the inactive N-acetylspermidine. In contrast, diverse phages encode spermidine N-acetyltransferase that can sequester spermidine into its inactive N-acetyl form. Together, the virome-encoded enzymes and pathways for biosynthesis and release or biochemical sequestration of spermidine or its structural analog homospermidine consolidate and expand evidence supporting an important and global role of spermidine in virus biology.

Keywords: bacteriophage; polyamine; putrescine; spermidine; virus

DOI: https://doi.org/10.1073/pnas.2214165120

Biomolecules. 2023 Feb 09. pii: 337. [Epub ahead of print]13(2):

Novel Green Fluorescent Polyamines to Analyze ATP13A2 and ATP13A3 Activity in the Mammalian Polyamine Transport System.

Marine Houdou, Nathalie Jacobs, Jonathan Coene, Mujahid Azfar, Roeland Vanhoutte, Chris Van den Haute, Jan Eggermont, Veronique Daniëls, Steven H L Verhelst, Peter Vangheluwe.

Cells acquire polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) via the complementary actions of polyamine uptake and synthesis pathways. The endosomal P5B-type ATPases ATP13A2 and ATP13A3 emerge as major determinants of mammalian polyamine uptake. Our biochemical evidence shows that fluorescently labeled polyamines are genuine substrates of ATP13A2. They can be used to measure polyamine uptake in ATP13A2- and ATP13A3-dependent cell models resembling radiolabeled polyamine uptake. We further report that ATP13A3 enables faster and stronger cellular polyamine uptake than does ATP13A2. We also compared the uptake of new green fluorescent PUT, SPD and SPM analogs using different coupling strategies (amide, triazole or isothiocyanate) and fluorophores (symmetrical BODIPY, BODIPY-FL and FITC). ATP13A2 promotes the uptake of various SPD and SPM analogs, whereas ATP13A3 mainly stimulates the uptake of PUT and SPD conjugates. However, the polyamine linker and coupling position on the fluorophore impacts the transport capacity, whereas replacing the fluorophore affects polyamine selectivity. The highest uptake in ATP13A2 or ATP13A3 cells is observed with BODIPY-FL-amide conjugated to SPD, whereas BODIPY-PUT analogs are specifically taken up via ATP13A3. We found that P5B-type ATPase isoforms transport fluorescently labeled polyamine analogs with a distinct structure-activity relationship (SAR), suggesting that isoform-specific polyamine probes can be designed.

Keywords: P5B-type ATPases; fluorescently labeled polyamines; mammalian polyamine transport systems; radiolabeled polyamines

DOI: https://doi.org/10.3390/biom13020337

Amino Acids. 2023 Feb 21.

A new 68Ga-labeled ornithine derivative for PET imaging of ornithine metabolism in tumors.

Hongliang Wang, Kaixin Qin, Dongmei Shi, Ping Wu, Xinzhong Hao, Haiyan Liu, Jie Gao, Jianguo Li, Zhifang Wu, Sijin Li.

Ornithine metabolism plays a vital role in tumorigenesis. For cancer cells, ornithine is mainly used as a substrate for ornithine decarboxylase (ODC) for the synthesis of polyamines. The ODC as a key enzyme of polyamine metabolism has become an important target for cancer diagnosis and treatment. To non-invasively detect the levels of ODC expression in malignant tumors, we have synthesized a novel 68Ga-labeled ornithine derivative ([68Ga]Ga-NOTA-Orn). The synthesis time of [68Ga]Ga-NOTA-Orn was about 30 min with a radiochemical yield of 45-50% (uncorrected), and the radiochemical purity was > 98%. [68Ga]Ga-NOTA-Orn was stable in saline and rat serum. Cellular uptake and competitive inhibition assays using DU145 and AR42J cells demonstrated that the transport pathway of [68Ga]Ga-NOTA-Orn was similar to that of L-ornithine, and it could interact with the ODC after transporting into the cell. Biodistribution and micro-positron emission tomography (Micro-PET) imaging studies showed that [68Ga]Ga-NOTA-Orn exhibited rapid tumor uptake and was rapidly excreted through the urinary system. All above results suggested that [68Ga]Ga-NOTA-Orn is a novel amino acid metabolic imaging agent with great potential of tumor diagnosis.

Keywords: Molecular probes; Ornithine; PET; Polyamines

DOI: https://doi.org/10.1007/s00726-023-03250-z

Proc Natl Acad Sci U S A. 2023 Feb 28. 120(9): e2216430120

Polyamines and linear DNA mediate bacterial threat assessment of bacteriophage infection.

Camilla D de Mattos, Dominick R Faith, Artem A Nemudryi, Amelia K Schmidt, DeAnna C Bublitz, Lauren Hammond, Margie A Kinnersley, Caleb M Schwartzkopf, Autumn J Robinson, Alex Joyce, Lia A Michaels, Robert S Brzozowski, Alison Coluccio, Denghui David Xing, Jumpei Uchiyama, Laura K Jennings, Prahathees Eswara, Blake Wiedenheft, Patrick R Secor.

Monitoring the extracellular environment for danger signals is a critical aspect of cellular survival. However, the danger signals released by dying bacteria and the mechanisms bacteria use for threat assessment remain largely unexplored. Here, we show that lysis of Pseudomonas aeruginosa cells releases polyamines that are subsequently taken up by surviving cells via a mechanism that relies on Gac/Rsm signaling. While intracellular polyamines spike in surviving cells, the duration of this spike varies according to the infection status of the cell. In bacteriophage-infected cells, intracellular polyamines are maintained at high levels, which inhibits replication of the bacteriophage genome. Many bacteriophages package linear DNA genomes and linear DNA is sufficient to trigger intracellular polyamine accumulation, suggesting that linear DNA is sensed as a second danger signal. Collectively, these results demonstrate how polyamines released by dying cells together with linear DNA allow P. aeruginosa to make threat assessments of cellular injury.

Keywords: Pseudomonas aeruginosa; bacteriophage; danger sensing; phage defense; polyamine

DOI: https://doi.org/10.1073/pnas.2216430120

J Cardiovasc Dev Dis. 2023 Jan 29. pii: 52. [Epub ahead of print]10(2):

Ciclopirox Inhibition of eIF5A Hypusination Attenuates Fibroblast Activation and Cardiac Fibrosis.

Kadiam C Venkata Subbaiah, Jiangbin Wu, Wai Hong Wilson Tang, Peng Yao.

Cardiac fibrosis is a primary contributor to heart failure (HF), and is considered to be a targetable process for HF therapy. Cardiac fibroblast (CF) activation accompanied by excessive extracellular matrix (ECM) production is central to the initiation and maintenance of fibrotic scarring in cardiac fibrosis. However, therapeutic compounds targeting CF activation remain limited in treating cardiac fibrosis. Eukaryotic translation initiation factor 5A (eIF5A), upon being hypusinated, is essential for the translation elongation of proline-codon rich mRNAs. In this study, we found that increased hypusinated eIF5A protein levels were associated with cardiac fibrosis and heart dysfunction in myocardial infarction (MI) mouse models. Ciclopirox (CPX), an FDA-approved antifungal drug, inhibits the deoxyhypusine hydroxylase (DOHH) enzyme required for eIF5A hypusination. Results from preventive and reversal mouse models suggest that CPX treatment significantly reduced MI-driven cardiac fibrosis and improved cardiac function. In vitro studies of isolated mouse primary CFs revealed that inhibition of eIF5A hypusination using CPX significantly abolished TGFβ induced CF proliferation, activation, and collagen expression. Proteomic analysis from mouse CFs reveals that CPX downregulates the expression of proline-rich proteins that are enriched in extracellular matrix and cell adhesion pathways. Our findings are relevant to human heart disease, as increased hypusinated eIF5A levels were observed in heart samples of ischemic heart failure patients compared to healthy subjects. Together, these results suggest that CPX can be repurposed to treat cardiac fibrosis and ischemic heart failure.

Keywords: ECM; ciclopirox; collagen; eIF5A; fibroblast; fibrosis; heart failure; translational control

DOI: https://doi.org/10.3390/jcdd10020052