Transgenic manipulation of a single polyamine in poplar cells affects the accumulation of all amino acids |
| |
Authors: | Sridev Mohapatra Rakesh Minocha Stephanie Long Subhash C Minocha |
| |
Institution: | (1) Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA;(2) Northern Research Station, USDA Forest Service, 271 Mast Road, Durham, NH 03824, USA;(3) Present address: Department of Biology, University of Texas, Arlington, TX 76019, USA; |
| |
Abstract: | The polyamine metabolic pathway is intricately connected to metabolism of several amino acids. While ornithine and arginine
are direct precursors of putrescine, they themselves are synthesized from glutamate in multiple steps involving several enzymes.
Additionally, glutamate is an amino group donor for several other amino acids and acts as a substrate for biosynthesis of
proline and γ-aminobutyric acid, metabolites that play important roles in plant development and stress response. Suspension
cultures of poplar (Populus nigra × maximowiczii), transformed with a constitutively expressing mouse ornithine decarboxylase gene, were used to study the effect of up-regulation
of putrescine biosynthesis (and concomitantly its enhanced catabolism) on cellular contents of various protein and non-protein
amino acids. It was observed that up-regulation of putrescine metabolism affected the steady state concentrations of most
amino acids in the cells. While there was a decrease in the cellular contents of glutamine, glutamate, ornithine, arginine,
histidine, serine, glycine, cysteine, phenylalanine, tryptophan, aspartate, lysine, leucine and methionine, an increase was
seen in the contents of alanine, threonine, valine, isoleucine and γ-aminobutyric acid. An overall increase in percent cellular
nitrogen and carbon content was also observed in high putrescine metabolizing cells compared to control cells. It is concluded
that genetic manipulation of putrescine biosynthesis affecting ornithine consumption caused a major change in the entire ornithine
biosynthetic pathway and had pleiotropic effects on other amino acids and total cellular carbon and nitrogen, as well. We
suggest that ornithine plays a key role in regulating this pathway. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|