In exploring the role of the chloroplast in the multiplication of turnip yellow mosaic virus, the biosyntheses of the major viral polyamine, spermidine, as well as that of the tetramine, spermine were studied. The synthesis of these polyamines from [2-(14)C]methionine in protoplasts of Chinese cabbage leaf cells derived from healthy plants or those infected by turnip yellow mosaic virus were ex...

In the polyamine back-conversion pathway, spermine and spermidine are first acetylated by spermidine/spermine N(1) -acetyl-transferase (SSAT-1) and then oxidized by polyamine oxidase to produce spermidine and putrescine respectively. Herein we apply homology-search methods to identify novel sequences belonging to a second SSAT, SSAT-2, with a chromosomal location at 17p13.1, which is distinct f...

We posed the question of whether steady-state levels of the higher polyamines spermidine and spermine in plants can be influenced by overexpression of a heterologous cDNA involved in the later steps of the pathway, in the absence of any further manipulation of the two synthases that are also involved in their biosynthesis. Transgenic rice (Oryza sativa) plants engineered with the heterologous D...

The cytotoxic effect of spermidine was investigated on various tissue culture cell lines in the presence of calf serum. Cells incubated with cytotoxic concentrations remained rounded up while cells in control cultures always spread out on the surface of the Petri dish. The spermidine concentration tolerated depends on cell number, concentration of serum, the strain of cells used and the phase o...

We measured the fluorescence intensity of DNA-bound fluorescent dyes YO-PRO-1 (oxazole yellow) and YOYO-1 (dimer of oxazole yellow) at various spermidine concentrations to determine how counterions on DNA are exchanged in the process of DNA condensation. A decrease of fluorescence intensity was observed with an increase of spermidine. Considering the chemical equilibrium under the competition b...

The polyamines putrescine (NH2(CH2)4NHs), spermidine (NH~(CH&NH(CH,)~~HZ), and spermine (NH2(CH&NH(CH2)fiH(CH&NH2) are widely distributed in nature. Fungi and animal tissues contain mainly spermidine and spermine (l6), whereas bacteria, especially gram-negative bacteria, contain mainly putrescine and spermidine (5-7) ; the amines have also been found in many plantsi (8) and in bacterial viruses...

The only pathway known for the biosynthesis of sperrnidine is from putrescine and S-adenosylmethionine. S-Adenosylmethionine is decarboxylated, and the aminopropyl group of the product is transferred to putrescine to form spermidine. The enzymes of this pathway, S-adenosylmethionine decarboxylase (EC 4.1.1 S O ) and aminopropyltransferase (EC 2.5.1.16), have been found in a number of bacteria, ...

Polyamine biosynthesis in senescing leaves of Avena sativa L. was measured by determining the activities of arginine decarboxylase (EC 4.1.1.19), ornithine decarboxylase (EC 4.1.1.17) and S-adenosyl-l-methionine decarboxylase (EC 4.1.1.50). Polyamine content was also estimated by thin layer chromatography and high performance liquid chromatography. Arginine decarboxylase activity decreases prog...

Vibrio cholerae, the causative agent of the devastating diarrheal disease cholera, can form biofilms on diverse biotic and abiotic surfaces. Biofilm formation is important for the survival of this organism both in its natural environment and in the human host. Development of V. cholerae biofilms are regulated by complex regulatory networks that respond to environmental signals. One of these sig...