bims-polyam 2024-05-05 papers

bims-polyam

Biomed News

on Polyamines

Issue of 2024–05–05
seven papers selected by
Sebastian J. Hofer, University of Graz

Rational engineering of homospermidine synthase for enhanced catalytic efficiency toward spermidine synthesis.
Arginase 2 attenuates ulcerative colitis by antioxidant effects of spermidine.
Polyamine-Mediated Sensitization of Klebsiella pneumoniae to Macrolides through a Dual Mode of Action.
Glutamine-derived aspartate is required for eIF5A hypusination-mediated translation of HIF-1α to induce the polarization of tumor-associated macrophages.
Spermine oxidase inhibitor, MDL 72527, reduced neovascularization, vascular permeability, and acrolein-conjugated proteins in a mouse model of ischemic retinopathy.
Arginine and its metabolites stimulate proliferation, differentiation, and physiological function of porcine trophoblast cells through β-catenin and mTOR pathways.
Polyaminated, acetylated and stop codon readthrough of recombinant Francisella tularensis universal stress protein in Escherichia coli.

Synth Syst Biotechnol. 2024 Sep;9(3): 549-557

Rational engineering of homospermidine synthase for enhanced catalytic efficiency toward spermidine synthesis.

Wenjing Liu, Xiaoxiang Hu, Yi Yan, Yujie Cai.

  Spermidine is a naturally occurring polyamine widely utilized in the prevention and treatment of various diseases. Current spermidine biosynthetic methods have problems such as low efficiency and complex multi-enzyme catalysis. Based on sequence-structure-function relationships, we engineered the widely studied homospermidine synthase from Blastochloris viridis (BvHSS) and obtained mutants that could catalyze the production of spermidine from 1,3-diaminopropane and putrescine. The specific activities of BvHSS and the mutants D361E and E232D + D361E (E232D-D) were 8.72, 46.04 and 48.30 U/mg, respectively. The optimal pH for both mutants was 9.0, and the optimal temperature was 50 °C. Molecular docking and dynamics simulations revealed that mutating aspartic acid at position 361 to glutamic acid narrowed the substrate binding pocket, promoting stable spermidine production. Conversely, mutating glutamic acid at position 232 to aspartic acid enlarged the substrate channel entrance, facilitating substrate entry into the active pocket and enhancing spermidine generation. In whole-cell catalysis lasting 6 h, D361E and E232D-D synthesized 725.3 and 933.5 mg/L of spermidine, respectively. This study offers a practical approach for single-enzyme catalyzed spermidine synthesis and sheds light on the crucial residues influencing homospermidine synthase catalytic activity in spermidine production.

Keywords:  Homospermidine synthase; Polyamine; Site-directed mutagenesis; Spermidine; Structural analysis

DOI:  https://doi.org/10.1016/j.synbio.2024.04.012
J Gastroenterol. 2024 May 02.

Arginase 2 attenuates ulcerative colitis by antioxidant effects of spermidine.

Noriyuki Imazu, Takehiro Torisu, Akihito Yokote, Junji Umeno, Keisuke Kawasaki, Shin Fujioka, Yuichi Matsuno, Tomohiro Nagasue, Shinichiro Kawatoko, Tomohiko Moriyama, Tomoki Nitahata, Yushi Uchida, Seishi Aihara, Yoshiaki Taniguchi, Yoshinao Oda, Takanari Kitazono.

   BACKGROUND: Spermidine suppress oxidative stress and is involved in various disease pathogenesis including ulcerative colitis (UC). Arginase 2 (ARG2) plays a central role in the synthesis of spermidine. This study aimed to clarify the effect of endogenously produced spermidine on colitis.
METHODS: The physiological role of ARG2 and spermidine was investigated using Arg2-deficient mice with reduced spermidine. Immunohistochemical staining of the rectum was used to analyze ARG2 expression and spermidine levels in healthy controls and UC patients.
RESULTS: In mice with dextran sulfate sodium-induced colitis, ARG2 and spermidine levels were increased in the rectal epithelium. Spermidine protects colonic epithelial cells from oxidative stress and Arg2 knockdown cells reduced antioxidant activity. Organoids cultured from the small intestine and colon of Arg2-deficient mice both were more susceptible to oxidative stress. Colitis was exacerbated in Arg2-deficient mice compared to wild-type mice. Supplementation with spermidine result in comparable severity of colitis in both wild-type and Arg2-deficient mice. In the active phase of UC, rectal ARG2 expression and spermidine accumulation were increased compared to remission. ARG2 and spermidine levels were similar in healthy controls and UC remission patients.
CONCLUSIONS: ARG2 produces spermidine endogenously in the intestinal epithelium and has a palliative effect on ulcerative colitis. ARG2 and spermidine are potential novel therapeutic targets for UC.

Keywords:  Antioxidant effect; Arginase 2; Spermidine; Ulcerative colitis

DOI:  https://doi.org/10.1007/s00535-024-02104-z
ACS Infect Dis. 2024 May 02.

Polyamine-Mediated Sensitization of Klebsiella pneumoniae to Macrolides through a Dual Mode of Action.

Joshua M E Adams, Peri B Moulding, Omar M El-Halfawy.

  Chemicals bacteria encounter at the infection site could shape their stress and antibiotic responses; such effects are typically undetected under standard lab conditions. Polyamines are small molecules typically overproduced by the host during infection and have been shown to alter bacterial stress responses. We sought to determine the effect of polyamines on the antibiotic response of Klebsiella pneumoniae, a Gram-negative priority pathogen. Interestingly, putrescine and other natural polyamines sensitized K. pneumoniae to azithromycin, a macrolide protein translation inhibitor typically used for Gram-positive bacteria. This synergy was further potentiated in the physiological buffer, bicarbonate. Chemical genomic screens suggested a dual mechanism, whereby putrescine acts at the membrane and ribosome levels. Putrescine permeabilized the outer membrane of K. pneumoniae (NPN and β-lactamase assays) and the inner membrane (Escherichia coli β-galactosidase assays). Chemically and genetically perturbing membranes led to a loss of putrescine-azithromycin synergy. Putrescine also inhibited protein synthesis in an E. coli-derived cell-free protein expression assay simultaneously monitoring transcription and translation. Profiling the putrescine-azithromycin synergy against a combinatorial array of antibiotics targeting various ribosomal sites suggested that putrescine acts as tetracyclines targeting the 30S ribosomal acceptor site. Next, exploiting the natural polyamine-azithromycin synergy, we screened a polyamine analogue library for azithromycin adjuvants, discovering four azithromycin synergists with activity starting from the low micromolar range and mechanisms similar to putrescine. This work sheds light on the bacterial antibiotic responses under conditions more reflective of those at the infection site and provides a new strategy to extend the macrolide spectrum to drug-resistant K. pneumoniae.

Keywords:  Gram-negative bacteria; antibiotic adjuvants; macrolides; polyamines; putrescine

DOI:  https://doi.org/10.1021/acsinfecdis.4c00157
Exp Mol Med. 2024 May 01.

Glutamine-derived aspartate is required for eIF5A hypusination-mediated translation of HIF-1α to induce the polarization of tumor-associated macrophages.

Dong-Ho Kim, Yoo Na Kang, Jonghwa Jin, Mihyang Park, Daehoon Kim, Ghilsuk Yoon, Jae Won Yun, Jaebon Lee, Soo Young Park, Yu Rim Lee, Jun-Kyu Byun, Yeon-Kyung Choi, Keun-Gyu Park.

Tumor-associated macrophages (TAMs) are vital contributors to the growth, metastasis, and therapeutic resistance of various cancers, including hepatocellular carcinoma (HCC). However, the exact phenotype of TAMs and the mechanisms underlying their modulation for therapeutic purposes have not been determined. Here, we present compelling evidence that glutamine-derived aspartate in TAMs stimulates spermidine production through the polyamine synthesis pathway, thereby increasing the translation efficiency of HIF-1α via eIF5A hypusination. Consequently, augmented translation of HIF-1α drives TAMs to undergo an increase glycolysis and acquire a metabolic phenotype distinct from that of M2 macrophages. Finally, eIF5A levels in tumor stromal lesions were greater than those in nontumor stromal lesions. Additionally, a higher degree of tumor stromal eIF5A hypusination was significantly associated with a more advanced tumor stage. Taken together, these data highlight the potential of inhibiting hypusinated eIF5A by targeting glutamine metabolism in TAMs, thereby opening a promising avenue for the development of novel therapeutic approaches for HCC.

DOI: https://doi.org/10.1038/s12276-024-01214-1
Tissue Barriers. 2024 Apr 29. 2347070

Spermine oxidase inhibitor, MDL 72527, reduced neovascularization, vascular permeability, and acrolein-conjugated proteins in a mouse model of ischemic retinopathy.

Abdullah Alhumaid, Fang Liu, Shengshuai Shan, Eissa Jafari, Nadia Nourin, Payaningal R Somanath, S Priya Narayanan.

  Disruptions in polyamine metabolism have been identified as contributing factors to various central nervous system disorders. Our laboratory has previously highlighted the crucial role of polyamine oxidation in retinal disease models, specifically noting elevated levels of spermine oxidase (SMOX) in inner retinal neurons. Our prior research demonstrated that inhibiting SMOX with MDL 72527 protected against vascular injury and microglial activation induced by hyperoxia in the retina. However, the effects of SMOX inhibition on retinal neovascularization and vascular permeability, along with the underlying molecular mechanisms of vascular protection, remain incompletely understood. In this study, we utilized the oxygen-induced retinopathy (OIR) model to explore the impact of SMOX inhibition on retinal neovascularization, vascular permeability, and the molecular mechanisms underlying MDL 72527-mediated vasoprotection in the OIR retina. Our findings indicate that inhibiting SMOX with MDL 72527 mitigated vaso-obliteration and neovascularization in the OIR retina. Additionally, it reduced OIR-induced vascular permeability and Claudin-5 expression, suppressed acrolein-conjugated protein levels, and downregulated P38/ERK1/2/STAT3 signaling. Furthermore, our results revealed that treatment with BSA-Acrolein conjugates significantly decreased the viability of human retinal endothelial cells (HRECs) and activated P38 signaling. These observations contribute valuable insights into the potential therapeutic benefits of SMOX inhibition by MDL 72527 in ischemic retinopathy.

Keywords:  Acrolein; MDL 72527; ischemic retinopathy; spermine oxidase; vascular damage; vision

DOI:  https://doi.org/10.1080/21688370.2024.2347070
BMC Vet Res. 2024 Apr 30. 20(1): 167

Arginine and its metabolites stimulate proliferation, differentiation, and physiological function of porcine trophoblast cells through β-catenin and mTOR pathways.

Shuai Li, Xiangyang Ye, Xiaolu Wen, Xuefen Yang, Li Wang, Kaiguo Gao, Hao Xiao, Zongyong Jiang.

  Arginine, which is metabolized into ornithine, proline, and nitric oxide, plays an important role in embryonic development. The present study was conducted to investigate the molecular mechanism of arginine in proliferation, differentiation, and physiological function of porcine trophoblast cells (pTr2) through metabolic pathways. The results showed that arginine significantly increased cell viability (P < 0.05). The addition of arginine had a quadratic tendency to increase the content of progesterone (P = 0.06) and protein synthesis rate (P = 0.03), in which the maximum protein synthesis rate was observed at 0.4 mM arginine. Arginine quadratically increased (P < 0.05) the intracellular contents of spermine, spermidine and putrescine, as well as linearly increased (P < 0.05) the intracellular content of NO in a dose-dependent manner. Arginine showed a quadratic tendency to increase the content of putrescine (P = 0.07) and a linear tendency to increase NO content (P = 0.09) in cell supernatant. Moreover, increasing arginine activated (P < 0.05) the mRNA expressions for ARG, ODC, iNOS and PCNA. Furthermore, inhibitors of arginine metabolism (L-NMMA and DFMO) both inhibited cell proliferation, while addition of its metabolites (NO and putrescine) promoted the cell proliferation and cell cycle, the mRNA expressions of PCNA, EGF and IGF-1, and increased (P < 0.05) cellular protein synthesis rate, as well as estradiol and hCG secretion (P < 0.05). In conclusion, our results suggested that arginine could promote cell proliferation and physiological function by regulating the metabolic pathway. Further studies showed that arginine and its metabolites modulate cell function mainly through β-catenin and mTOR pathways.

Keywords:  Arginine; Cell proliferation; Porcine trophoblast cells

DOI:  https://doi.org/10.1186/s12917-024-04023-w
PLoS One. 2024 ;19(4): e0299701

Polyaminated, acetylated and stop codon readthrough of recombinant Francisella tularensis universal stress protein in Escherichia coli.

Benjamin Girardo, Lawrence M Schopfer, Yinshi Yue, Oksana Lockridge, Marilynn A Larson.

Recombinant Francisella tularensis universal stress protein with a C-terminal histidine-tag (rUsp/His6) was expressed in Escherichia coli. Endogenous F. tularensis Usp has a predicted molecular mass of 30 kDa, but rUsp/His6 had an apparent molecular weight of 33 kDa based on Western blot analyses. To determine the source of the higher molecular weight for rUsp/His6, post translational modifications were examined. Tryptic peptides of purified rUsp/His6 were subjected to liquid chromatography tandem mass spectrometry (LC-MS/MS) and fragmentation spectra were searched for acetylated lysines and polyaminated glutamines. Of the 24 lysines in rUsp/His6, 10 were acetylated (K63, K68, K72, K129, K175, K201, K208, K212, K233, and K238) and three of the four glutamines had putrescine, spermidine and spermine adducts (Q55, Q60 and Q267). The level of post-translational modification was substoichiometric, eliminating the possibility that these modifications were the sole contributor to the 3 kDa extra mass of rUsp/His6. LC-MS/MS revealed that stop codon readthrough had occurred resulting in the unexpected addition of 20 extra amino acids at the C-terminus of rUsp/His6, after the histidine tag. Further, the finding of polyaminated glutamines in rUsp/His6 indicated that E. coli is capable of transglutaminase activity.

DOI: https://doi.org/10.1371/journal.pone.0299701