Affordable Access

Early Steps in the Biosynthesis of NAD in Arabidopsis Start with Aspartate and Occur in the Plastid1

Authors
Publisher
American Society of Plant Biologists
Publication Date
Source
PMC
Keywords
  • Research Article
Disciplines
  • Biology

Abstract

NAD is a ubiquitous coenzyme involved in oxidation-reduction reactions and is synthesized by way of quinolinate. Animals and some bacteria synthesize quinolinate from tryptophan, whereas other bacteria synthesize quinolinate from aspartate (Asp) using l-Asp oxidase and quinolinate synthase. We show here that Arabidopsis (Arabidopsis thaliana) uses the Asp-to-quinolinate pathway. The Arabidopsis l-Asp oxidase or quinolinate synthase gene complemented the Escherichia coli mutant defective in the corresponding gene, and T-DNA-based disruption of either of these genes, as well as of the gene coding for the enzyme quinolinate phosphoribosyltransferase, was embryo lethal. An analysis of functional green fluorescent protein-fused constructs and in vitro assays of uptake into isolated chloroplasts demonstrated that these three enzymes are located in the plastid.

There are no comments yet on this publication. Be the first to share your thoughts.