Polyamines are small polycations that are well conserved in all the living organisms except Archae, Methanobacteriales and Halobacteriales. The most common polyamines are putrescine, spermidine and spermine, which exist in varying concentrations in different organisms. They are involved in a variety of cellular processes such as gene expression, cell growth, survival, stress response and proliferation. Therefore, diverse regulatory pathways are evolved to ensure strict regulation of polyamine concentration in the cells. Polyamine levels are kept under strict control by biosynthetic pathways as well as cellular uptake driven by specific transporters. Reverse genetic studies in microorganisms showed that deletion of the genes in polyamine metabolic pathways or depletion of polyamines have negative effects on cell survival and proliferation. The protein products of these genes are also used as drug targets against pathogenic protozoa. These altogether confirm the significant roles of polyamines in the cells. This mini-review focuses on the differential concentrations of polyamines and their cellular functions in different microorganisms. This will provide an insight about the diverse evolution of polyamine metabolism and function based on the physiology and the ecological context of the microorganisms.
Fission yeast Schizosaccharomyces pombe has a variety of stress-signaling proteins that protect cells against environmental or intracellular stress. These proteins help the cells to respond to stress conditions and regulate intracellular functions such as cell division or gene expression. Polyamines (spermidine, spermine, and putrescine) are known to be important in the regulation of stress response and cell division. In this study, we tried to experimentally characterize novel S. pombe genes that are involved in the polyamine pathway and understand their potential roles. Sequence analysis revealed four genes that code for (predicted) spermidine family transporters in S. pombe. In an attempt to characterize these (predicted) spermidine family transmembrane transporters and their possible roles, deletion mutants of these candidate genes were created. These mutants were exposed to different stress conditions, such as DNAdamaging agents and osmotic stress, to understand their significance in the stress response. Next, the mutants were analyzed in terms of cell size, growth rate, and spore formation to understand their contribution to cell cycle control. The results revealed that individual deletion of two of these genes, SPBC36.01c and SPBC36.02c, resulted in sensitivity to DNA-damaging agents, indicating their role in DNA damage response.
Polyamines are well conserved polycationic molecules that are known to interact with nucleic acids and contribute to multiple functions including cell cycle and stress response. The transport of polyamines in and out of the cell is driven by polyamine transporters that play a significant role in polyamine homeostasis. Schizosaccharomyces pombe (Lindner) caf5 + gene codes for a spermine family transporter that is yet to be characterized functionally. This study aims to understand the contribution of caf5 + on different processes previously associated with polyamines, by reverse genetics. Deletion mutants of caf5 + , which are viable in normal conditions, were scanned for multiple cellular processes. The results showed that caf5 + deletion caused shorter cell length and slightly faster growth rate at the optimum conditions. caf5Δ cells also showed sensitivity to high doses of UV irradiation, while no sensitivity was observed against osmotic stress or another DNA damaging agent hydroxyurea. The mutants could successfully go through different phases of mitosis and meiosis as observed by DNA and septum staining. In summary, caf5 + gene is involved in normal growth and cell cycle progression, as well as stress response upon UV irradiation.
Polyamines are well-conserved, multifunctional polycations that contribute to a number of processes in the cells such as cell cycle, apoptosis, stress response, and gene expression. Therefore, polyamine levels should be kept under strict regulation by specific polyamine transporters and polyamine synthases. In this study, the aim is to experimentally characterize a predicted spermidine synthase gene srm1, which was identified upon sequence similarity, in fission yeast Schizosaccharomyces pombe. In an attempt to understand the role of this gene in cell cycle and stress response, deletion mutant of srm1 was generated and analyzed in terms of cell cycle regulation and environmental stress response. The results showed that srm1Δ cells had elongated cell size and were sensitive to osmotic stress, while they showed no sensitivity to DNA-damaging agents. To the best of our knowledge, this is the first experimental characterization of srm1 gene and its role in cell cycle progression and stress response.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.