bims-polyam 2024-04-14 papers

Issue of 2024–04–14
four papers selected by
Sebastian J. Hofer, University of Graz

J Biol Chem. 2024 Apr 06. pii: S0021-9258(24)01782-4. [Epub ahead of print] 107281

Functional identification of bacterial spermine, thermospermine, norspermine, norspermidine, spermidine, and N1-aminopropylagmatine synthases.

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

Spermine synthase is an aminopropyltransferase that adds an aminopropyl group to the essential polyamine spermidine to form tetraamine spermine, needed for normal human neural development, plant salt and drought resistance, and yeast CoA biosynthesis. We functionally identify for the first time bacterial spermine synthases, derived from phyla Bacillota, Rhodothermota, Thermodesulfobacteriota, Nitrospirota, Deinococcota and Pseudomonadota. We also identify bacterial aminopropyltransferases that synthesize the spermine same mass isomer thermospermine, from phyla Cyanobacteriota, Thermodesulfobacteriota, Nitrospirota, Dictyoglomota, Armatimonadota and Pseudomonadota, including the human opportunistic pathogen Pseudomonas aeruginosa. Most of these bacterial synthases were capable of synthesizing spermine or thermospermine from the diamine putrescine, and so possess also spermidine synthase activity. We found that most thermospermine synthases could synthesize tetraamine norspermine from triamine norspermidine, i.e., they are potential norspermine synthases. This finding could explain the enigmatic source of norspermine in bacteria. Some of the thermospermine synthases could synthesize norspermidine from diamine 1,3-diaminopropane, demonstrating that they are potential norspermidine synthases. Of 18 bacterial spermidine synthases identified, 17 were able to aminopropylate agmatine to form N1-aminopropylagmatine, including the spermidine synthase of Bacillus subtilis, a species known to be devoid of putrescine. This suggests that the N1-aminopropylagmatine pathway for spermidine biosynthesis, which bypasses putrescine, may be far more widespread than realized and may be the default pathway for spermidine biosynthesis in species encoding L-arginine decarboxylase for agmatine production. Some thermospermine synthases were able to aminopropylate N1-aminopropylagmatine to form N12-guanidinothermospermine. Our study reveals an unsuspected diversification of bacterial polyamine biosynthesis, and suggests a more prominent role for agmatine.

Keywords: N(1)-aminopropylagmatine; bacterial metabolism; biosynthesis; norspermidine; norspermine; polyamine; spermidine; spermine; thermospermine

DOI: https://doi.org/10.1016/j.jbc.2024.107281

Redox Biol. 2024 Apr 03. pii: S2213-2317(24)00127-7. [Epub ahead of print]72 103151

Salmonella Typhimurium employs spermidine to exert protection against ROS-mediated cytotoxicity and rewires host polyamine metabolism to ameliorate its survival in macrophages.

Abhilash Vijay Nair, Anmol Singh, R S Rajmani, Dipshikha Chakravortty.

Salmonella infection entails a cascade of attacks and defence measures. After breaching the intestinal epithelial barrier, Salmonella is phagocytosed by macrophages, where the bacteria encounter multiple stresses, to which it employs relevant countermeasures. Our study shows that, in Salmonella, the polyamine spermidine activates a stress response mechanism by regulating critical antioxidant genes. Salmonella Typhimurium mutants for spermidine transport and synthesis cannot mount an antioxidative response, resulting in high intracellular ROS levels. These mutants are also compromised in their ability to be phagocytosed by macrophages. Furthermore, it regulates a novel enzyme in Salmonella, Glutathionyl-spermidine synthetase (GspSA), which prevents the oxidation of proteins in E. coli. Moreover, the spermidine mutants and the GspSA mutant show significantly reduced survival in the presence of hydrogen peroxide in vitro and reduced organ burden in the mouse model of Salmonella infection. Conversely, in macrophages isolated from gp91phox-/- mice, we observed a rescue in the attenuated fold proliferation previously observed upon infection. We found that Salmonella upregulates polyamine biosynthesis in the host through its effectors from SPI-1 and SPI-2, which addresses the attenuated proliferation observed in spermidine transport mutants. Thus, inhibition of this pathway in the host abrogates the proliferation of Salmonella Typhimurium in macrophages. From a therapeutic perspective, inhibiting host polyamine biosynthesis using an FDA-approved chemopreventive drug, D, L-α-difluoromethylornithine (DFMO), reduces Salmonella colonisation and tissue damage in the mouse model of infection while enhancing the survival of infected mice. Therefore, our work provides a mechanistic insight into the critical role of spermidine in stress resistance of Salmonella. It also reveals a bacterial strategy in modulating host metabolism to promote their intracellular survival and shows the potential of DFMO to curb Salmonella infection.

Keywords: Antioxidative response; D; Glutathionyl-spermidine synthetase; L-α-difluoromethylornithine; Macrophages; Spermidine

DOI: https://doi.org/10.1016/j.redox.2024.103151

Structure. 2024 Mar 27. pii: S0969-2126(24)00090-X. [Epub ahead of print]

Crystal structure of archaeal IF5A-DHS complex reveals insights into the hypusination mechanism.

Mattia D'Agostino, Angelita Simonetti, Stefano Motta, Philippe Wolff, Alice Romagnoli, Astra Piccinini, Francesco Spinozzi, Daniele Di Marino, Anna La Teana, Eric Ennifar.

The translation factor IF5A is highly conserved in Eukarya and Archaea and undergoes a unique post-translational hypusine modification by the deoxyhypusine synthase (DHS) enzyme. DHS transfers the butylamine moiety from spermidine to IF5A using NAD as a cofactor, forming a deoxyhypusine intermediate. IF5A is a key player in protein synthesis, preventing ribosome stalling in proline-rich sequences during translation elongation and facilitating translation elongation and termination. Additionally, human eIF5A participates in various essential cellular processes and contributes to cancer metastasis, with inhibiting hypusination showing anti-proliferative effects. The hypusination pathway of IF5A is therefore an attractive new therapeutic target. We elucidated the 2.0 Å X-ray crystal structure of the archaeal DHS-IF5A complex, revealing hetero-octameric architecture and providing a detailed view of the complex active site including the hypusination loop. This structure, along with biophysical data and molecular dynamics simulations, provides new insights into the catalytic mechanism of the hypusination reaction.

Keywords: ITC calorimetry; X-ray structure; biophysics; deoxyhypusine synthase; initiation factor 5A; oncogenesis

DOI: https://doi.org/10.1016/j.str.2024.03.008

Adv Sci (Weinh). 2024 Apr 11. e2310162

Spermidine-Functionalized Injectable Hydrogel Reduces Inflammation and Enhances Healing of Acute and Diabetic Wounds In Situ.

Qianqian Wu, Runjiao Yang, Wenxuan Fan, Li Wang, Jing Zhan, Tingting Cao, Qiming Liu, Xianshu Piao, Yinghui Zhong, Wenxian Zhao, Shuhan Zhang, Jiaao Yu, Song Liang, Thomas M Roberts, Bingdi Wang, Zhenning Liu.

The inflammatory response is a key factor affecting tissue regeneration. Inspired by the immunomodulatory role of spermidine, an injectable double network hydrogel functionalized with spermidine (DN-SPD) is developed, where the first and second networks are formed by dynamic imine bonds and non-dynamic photo-crosslinked bonds respectively. The single network hydrogel before photo-crosslinking exhibits excellent injectability and thus can be printed and photo-crosslinked in situ to form double network hydrogels. DN-SPD hydrogel has demonstrated desirable mechanical properties and tissue adhesion. More importantly, an "operando" comparison of hydrogels loaded with spermidine or diethylenetriamine (DETA), a sham molecule resembling spermidine, has shown similar physical properties, but quite different biological functions. Specifically, the outcomes of 3 sets of in vivo animal experiments demonstrate that DN-SPD hydrogel can not only reduce inflammation caused by implanted exogenous biomaterials and reactive oxygen species but also promote the polarization of macrophages toward regenerative M2 phenotype, in comparison with DN-DETA hydrogel. Moreover, the immunoregulation by spermidine can also translate into faster and more natural healing of both acute wounds and diabetic wounds. Hence, the local administration of spermidine affords a simple but elegant approach to attenuate foreign body reactions induced by exogenous biomaterials to treat chronic refractory wounds.

Keywords: biomaterials; hydrogel; inflammation; spermidine; wound healing

DOI: https://doi.org/10.1002/advs.202310162