Heterotic patterns of sugar and amino acid components in developing maize kernels.

Heterosis is the superior performance of hybrids over their inbred parents. Despite its importance, little is known about the genetic and molecular basis of this phenomenon. Heterosis has been extensively exploited in plant breeding, particularly in maize (Zea mays, L.

A novel isoform of pantothenate synthetase in the Archaea.

The linear biosynthetic pathway leading from alpha-ketoisovalerate to pantothenate (vitamin B5) and on to CoA comprises eight steps in the Bacteria and Eukaryota. Genes for up to six steps of this pathway can be identified by sequence homology in individual archaeal genomes. However, there are no archaeal homologs to known isoforms of pantothenate synthetase (PS) or pantothenate kinase.

Pantothenate synthetase is essential but not limiting for pantothenate biosynthesis in Arabidopsis.

Pantothenate (vitamin B5) is the universal precursor for coenzyme A (CoA), an essential cofactor that is required in the metabolism of carbohydrates and fatty acids. The final step of bacterial and eukaryotic pantothenate biosynthesis is catalyzed by pantothenate synthetase (PTS), which is encoded by a single gene in Arabidopsis thaliana (AtPTS). There was debate whether PTS represents the only mode of pantothenate production because previous biochemical evidence pointed to an additional pantothenate pathway in plants.

Molecular adaptation and allostery in plant pantothenate synthetases.

Pantothenate synthetase catalyzes the ATP-dependent condensation of pantoate and beta-alanine to yield pantothenate, the essential precursor to coenzyme A. Bacterial and plant pantothenate synthetases are dimeric enzymes that share significant sequence identity. Here we show that the two-step reaction mechanism of pantothenate synthetase is conserved between the enzymes from Arabidopsis thaliana and Escherichia coli.

Robustness of central carbohydrate metabolism in developing maize kernels.

The central carbohydrate metabolism provides the precursors for the syntheses of various storage products in seeds. While the underlying biochemical map is well established, little is known about the organization and flexibility of carbohydrate metabolic fluxes in the face of changing biosynthetic demands or other perturbations. This question was addressed in developing kernels of maize (Zea mays L.

Changes in flux pattern of the central carbohydrate metabolism during kernel development in maize.

Developing kernels of the inbred maize line W22 were grown in sterile culture and supplied with a mixture of [U-13C6]glucose and unlabeled glucose during three consecutive intervals (11-18, 18-25, or 25-32 days after pollination) within the linear phase of starch formation. At the end of each labeling period, glucose was prepared from starch and analyzed by 13C isotope ratio mass spectrometry and high-resolution (13)C NMR spectroscopy. The abundances of individual glucose isotopologs were calculated by computational deconvolution of the NMR data.

Coenzyme A biosynthesis: reconstruction of the pathway in archaea and an evolutionary scenario based on comparative genomics.

Coenzyme A (CoA) holds a central position in cellular metabolism and therefore can be assumed to be an ancient molecule. Starting from the known E. coli and human enzymes required for the biosynthesis of CoA, phylogenetic profiles and chromosomal proximity methods enabled an almost complete reconstruction of archaeal CoA biosynthesis.

The sugary-type isoamylase in wheat: tissue distribution and subcellular localisation.

To gain an increased understanding of the role of isoamylase (EC 3.2.1.