Polyamines as Endogenous Growth Regulators

Galston, Arthur W.; Kaur‐Sawhney, Ravindar

doi:10.1007/978-94-011-0473-9_8

Cited by 121 publications

(45 citation statements)

References 42 publications

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“…With respect to the ubiquitous occurrence of putrescine (51), it is still unresolved whether homospermidine is synthesized in vivo in tobacco without being accumulated in detectable amounts or whether the formation of homospermidine is the result of indiscriminate enzyme activity detectable only in vitro. The occurrence of homospermidine has not been reported for tobacco, although this plant is rather frequently used in polyamine research (52)(53)(54). However, a recent GC-MS analysis of the polyamine fraction of young tobacco leaves revealed very small but unambiguously detectable amounts of homospermidine.…”

Section: Assaymentioning

confidence: 99%

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Deoxyhypusine Synthase from Tobacco

Ober

Hartmann

1999

Journal of Biological Chemistry

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Deoxyhypusine synthase catalyzes the formation of a deoxyhypusine residue in the translation eukaryotic initiation factor 5A (eIF5A) precursor protein by transferring an aminobutyl moiety from spermidine onto a conserved lysine residue within the eIF5A polypeptide chain. This reaction commences the activation of the initiation factor in fungi and vertebrates. A mechanistically identical reaction is known in the biosynthetic pathway leading to pyrrolizidine alkaloids in plants. Deoxyhypusine synthase from tobacco was cloned and expressed in active form in Escherichia coli. It catalyzes the formation of a deoxyhypusine residue in the tobacco eIF5A substrate as shown by gas chromatography coupled with a mass spectrometer. The enzyme also accepts free putrescine as the aminobutyl acceptor, instead of lysine bound in the eIF5A polypeptide chain, yielding homospermidine. Conversely, it accepts homospermidine instead of spermidine as the aminobutyl donor, whereby the reactions with putrescine and homospermidine proceed at the same rate as those involving the authentic substrates. The conversion of deoxyhypusine synthase-catalyzed eIF5A deoxyhypusinylation pinpoints a function for spermidine in plant metabolism. Furthermore, and quite unexpectedly, the substrate spectrum of deoxyhypusine synthase hints at a biochemical basis behind the sparse and skew occurrence of both homospermidine and its pyrrolizidine derivatives across distantly related plant taxa.The eukaryotic initiation factor 5A (eIF5A), 1 a small 17.4-kDa protein, is activated by a post-translational modification of a specific lysine residue to hypusine (N ⑀ -(4-amino-2-hydroxybutyl)lysine) in an enzyme-catalyzed two-step mechanism (reviewed in Refs. 1 and 2). In the first step, the aminobutyl moiety of the polyamine spermidine is transferred by deoxyhypusine synthase (EC 1.1.1.249) in an NAD ϩ -dependent reaction to the ⑀-amino group of a specific lysine residue in the eIF5A precursor protein to form deoxyhypusine. In the second step, deoxyhypusine hydroxylase (EC 1.14.99.29) catalyzes the hydroxylation of the deoxyhypusine residue to hypusine. Activated eIF5A is the only protein in which the unusual amino acid hypusine has been detected to date (3, 4), the modification is one of the most specific post-translational modifications known (5, 6). eIF5A seems to be ubiquitous among eukaryotes (7) and archaebacteria (8). Its amino acid sequence is highly conserved, and the 12 amino acids surrounding the hypusine residue are identical in all eukaryotes studied. Although known for nearly 2 decades, the function of eIF5A is still obscure. Because of its in vitro activity in stimulating methionyl puromycin synthesis (9), eIF5A was classified as a protein synthesis initiation factor, though subsequent doubts have arisen as to whether initiation of protein synthesis is a major function of this protein (2). Using a yeast mutant, it was shown that depletion of eIF5A causes an immediate inhibition of cell growth but only a moderate inhibition (30%) of total protein synthe...

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Section: Assaymentioning

confidence: 99%

“…This function is still unknown. Among plant physiologists, the suspected but unknown roles of spermidine in plant growth and development are controversially discussed (52)(53)(54)(55). The requirement of spermidine as an essential substrate for deoxyhypusine formation provides direct evidence for a function of this polyamine in plant metabolism.…”

Section: Assaymentioning

confidence: 99%

Deoxyhypusine Synthase from Tobacco

Ober

Hartmann

1999

Journal of Biological Chemistry

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“…The plant polyamine biosynthetic pathway is relatively simple [14]. Putrescine is derived either from ornithine catalyzed by ornithine decarboxylase (ODC) or from arginine through several steps catalyzed by arginine decarboxylase (ADC), agmatine iminohydrolase and N-carbamoylputrescine amidohydrolase.…”

Section: Introductionmentioning

confidence: 99%

“…Previous observations revealed that polyamines may be involved in a variety of plant developmental processes, such as cell division, root initiation, somatic embryogenesis, xylogenesis, flower development, fruit ripening and senescence [3]. Recent studies have indicated that polyamines also affect the formation of plant architecture, such as internode elongation [10,11], root branching [12] and shoot apical dominance [13].The plant polyamine biosynthetic pathway is relatively simple [14]. Putrescine is derived either from ornithine catalyzed by ornithine decarboxylase (ODC) or from arginine through several steps catalyzed by arginine decarboxylase (ADC), agmatine iminohydrolase and N-carbamoylputrescine amidohydrolase.…”

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confidence: 99%

BUD2, encoding an S-adenosylmethionine decarboxylase, is required for Arabidopsis growth and development

et al. 2006

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Polyamines are implicated in regulating various developmental processes in plants, but their exact roles and how they govern these processes still remain elusive. We report here an Arabidopsis bushy and dwarf mutant, bud2, which results from the complete deletion of one member of the small gene family that encodes S-adenosylmethionine decarboxylases (SAMDCs) necessary for the formation of the indispensable intermediate in the polyamine biosynthetic pathway. The bud2 plant has enlarged vascular systems in inflorescences, roots, and petioles, and an altered homeostasis of polyamines. The double mutant of bud2 and samdc1, a knockdown mutant of another SAMDC member, is embryo lethal, demonstrating that SAMDCs are essential for plant embryogenesis. Our results suggest that polyamines are required for the normal growth and development of higher plants.Cell Research (2006) IntroductionPolyamines, including diamine putrescine, triamine spermidine and tetraamine spermine, are aliphatic nitrogen compounds distributed widely from bacteria to higher plants [1,2] and have been implicated to play important roles in growth and development [3]. At the cellular level, polyamines are organic cations, interacting with the macromolecules that possess anionic groups such as DNA, RNA, lipids and proteins, thereby influencing DNA conformation, gene expression and protein synthesis, and modulating enzyme activity. In higher plants, polyamines are able to affect membrane fluidity by binding to phospholipids in membrane [4] and mediate biotic and abiotic stress responses, such as pathogen infection, osmotic stress, potassium deficiency and wounding [5][6][7][8][9]. Previous observations revealed that polyamines may be involved in a variety of plant developmental processes, such as cell division, root initiation, somatic embryogenesis, xylogenesis, flower development, fruit ripening and senescence [3]. Recent studies have indicated that polyamines also affect the formation of plant architecture, such as internode elongation [10,11], root branching [12] and shoot apical dominance [13].The plant polyamine biosynthetic pathway is relatively simple [14]. Putrescine is derived either from ornithine catalyzed by ornithine decarboxylase (ODC) or from arginine through several steps catalyzed by arginine decarboxylase (ADC), agmatine iminohydrolase and N-carbamoylputrescine amidohydrolase. Spermidine and spermine are synthesized from putrescine through spermidine and spermine synthases (SPDS and SPMS) from the donor of decarboxylated S-adenosylmethionine (dcSAM), which is produced from S-adenosylmethionine (SAM) by the action of S-adenosylmethionine decarboxylase (SAMDC).Although application of inhibitors is very useful in studying the polyamine biosynthetic pathway and in ex- [11,[19][20][21][22][23][24]. However, no mutant defective in SAMDC has been reported yet, although SAMDC cDNAs were cloned and their transgenic plants have been generated [25][26][27][28][29]. In this paper, we report the isolation and characterization of an Arabidopsis...

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“…Reciprocal cross-pollination between the cosuppressed and wild-type flowers indicated that reduced fertility was due to a pollen defect in the transgenic plants. These phenotypic abnormalities may be caused by the increased accumulation of putrescine and spermidine, which may have hormonal functions during plant development (24). Alternatively, a reduction in the MP supply might cause the accumulation of precursors for the nicotinic acid moiety of nicotine, and, at high levels, these precursors might be responsible for the abnormalities.…”

Section: Resultsmentioning

confidence: 99%

Inaugural Article: Metabolic engineering of plant alkaloid biosynthesis

Sato

Hashimoto²,

Hachiya³

et al. 2000

Proceedings of the National Academy of Sciences

102

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Plant alkaloids, one of the largest groups of natural products, provide many pharmacologically active compounds. Several genes in the biosynthetic pathways for scopolamine, nicotine, and berberine have been cloned, making the metabolic engineering of these alkaloids possible. Expression of two branching-point enzymes was engineered: putrescine N-methyltransferase (PMT) in transgenic plants of Atropa belladonna and Nicotiana sylvestris and (S)-scoulerine 9-Omethyltransferase (SMT) in cultured cells of Coptis japonica and Eschscholzia californica. Overexpression of PMT increased the nicotine content in N. sylvestris, whereas suppression of endogenous PMT activity severely decreased the nicotine content and induced abnormal morphologies. Ectopic expression of SMT caused the accumulation of benzylisoquinoline alkaloids in E. californica. The prospects and limitations of engineering plant alkaloid metabolism are discussed.berberine ͉ nicotine ͉ polyamine ͉ sanguinarine ͉ scopolamine H igher plants constitute one of our most important natural resources. They provide not only foodstuffs, fibers, and woods, but many chemicals, such as oils, flavorings, dyes, and pharmaceuticals. Although plants are renewable resources, some species are becoming more difficult to obtain in sufficient amounts to meet increasing demands. Destruction of natural habitats and technical difficulties in cultivation also are driving the drastic reductions in plant availability. For example, it is claimed that the demand for paclitaxel, a potent anticancer compound, could endanger forests of Taxus brevifolia (Pacific yew) because of the low paclitaxel content (40-100 mg͞kg of bark) in and slow growth of the trees (1).For many natural chemicals it is possible to synthesize alternatives from petroleum, coal, or both. The economic limitations of chemical synthesis and the pollution that accompanies this type of chemical synthesis, however, have led to the development of cell culture and molecular engineering of plants for the production of important and commodity chemicals. Plant cell and organ culture offer promising alternatives for the production of chemicals because totipotency enables plant cells and organs to produce useful secondary metabolites in vitro (2). Cell culture is also advantageous in that useful metabolites are obtained under a controlled environment, independent of climatic changes and soil conditions. In addition, the products are free of microbe and insect contamination. Fermentation technology also can be used to produce desired metabolites and can be optimized to maintain high and stable yields of known quality by cellular and molecular breeding techniques to further improve productivity and quality. After extensive empirical trials, some metabolites are now being produced by large-scale cell culture (e.g., shikonin and berberine; ref. 2), but the numbers of compounds that are producible commercially by cell culture technology are still very few. The main limitations are low productivity and the necessity of the down-stream pr...

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Polyamines as Endogenous Growth Regulators

Cited by 121 publications

References 42 publications

Deoxyhypusine Synthase from Tobacco

Deoxyhypusine Synthase from Tobacco

BUD2, encoding an S-adenosylmethionine decarboxylase, is required for Arabidopsis growth and development

Inaugural Article: Metabolic engineering of plant alkaloid biosynthesis

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