Engineering the expression level of cytosolic nucleoside diphosphate kinase in transgenic Solanum tuberosum roots alters growth, respiration and carbon metabolism

Abstract

Nucleoside diphosphate kinase (NDPK) is a ubiquitous enzyme that catalyzes the transfer of the γ-phosphate from a donor nucleoside triphosphate to an acceptor nucleoside diphosphate. In this study we used a targeted metabolomic approach and measurement of physiological parameters to report the effects of the genetic manipulation of cytosolic NDPK (NDPK1) expression on physiology and carbon metabolism in potato (Solanum tuberosum) roots. Sense and antisense NDPK1 constructs were introduced in potato using Agrobacterium rhizogenes to generate a population of root clones displaying a 40-fold difference in NDPK activity. Root growth, O uptake, flux of carbon between sucrose and CO , levels of reactive oxygen species and some tricarboxylic acid cycle intermediates were positively correlated with levels of NDPK1 expression. In addition, NDPK1 levels positively affected UDP-glucose and cellulose contents. The activation state of ADP-glucose pyrophosphorylase, a key enzyme in starch synthesis, was higher in antisense roots than in roots overexpressing NDPK1. Further analyses demonstrated that ADP-glucose pyrophosphorylase was more oxidized, and therefore less active, in sense clones than antisense clones. Consequently, antisense NDPK1 roots accumulated more starch and the starch to cellulose ratio was negatively affected by the level of NDPK1. These data support the idea that modulation of NDPK1 affects the distribution of carbon between starch and cellulose biosynthetic pathways.

Plant nucleoside diphosphate kinase 1: A housekeeping enzyme with moonlighting activity

“…Recently, we have used a genetic approach to test the implication of NDPK1 in carbohydrate metabolism. 16 This work provides evidence that the above hypothesis is valid and that the role of NDPK1 in plants may very well lie beyond a simple housekeeping function. 16 NDPK1 levels modify starch and cellulose contents in transgenic roots NDPK1 activity allows a straightforward transfer of energy between adenine and uridine nucleotide pools in the cytosol.…”

“…16 This work provides evidence that the above hypothesis is valid and that the role of NDPK1 in plants may very well lie beyond a simple housekeeping function. 16 NDPK1 levels modify starch and cellulose contents in transgenic roots NDPK1 activity allows a straightforward transfer of energy between adenine and uridine nucleotide pools in the cytosol. 23 The main effects of decreasing and increasing NDPK1 levels are respectively presented in Figure 2a and 2b.…”

“…Arabidopsis, rice, and potato). 16,29 Another NDPK1 moonlighting activity is suggested by a recent study providing evidence that Arabidopsis NDPK1 interacts with several proteins involved in translation initiation and mRNA processing or metabolism. 27 This activity could also be implicated in the regulation of HK genes.…”

“…Studies in potato demonstrate that NDPK1, belonging to Type I, constitute the bulk of NDPK activity and likely represents the most highly expressed isoform. [14][15][16] In various species, expression of NDPK1 is spatio-temporally regulated during growth and development. [17][18][19][20] In potato roots, immunolocalization studies have demonstrated the enhanced expression of NDPK1 in meristems and provascular tissues.…”

UMP Kinase Regulates Chloroplast Development and Cold Response in Rice

“…In our study, H 2 O 2 was highly accumulated in the umpk mutant under normal conditions. This indicates that the UMP kinase is critical for maintaining appropriate ROS metabolism in rice, which is similar to four other enzymes involved in nucleotide metabolism, including nucleoside diphosphate kinase 1, nucleoside diphosphate kinase 2, glutamine phosphoribosyl pyrophosphate amidotransferase 2, and allantoinase [4,41,42,43]. In addition to the high accumulation of ROS, high activities of SOD and POD were also observed in the mutant under normal conditions.…”