Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nicotianamine (NA) is a non-protein amino acid derivative synthesized from S-adenosyl L-methionine able to bind several metal ions such as iron, copper, manganese, zinc, or nickel. In plants, NA appears to be involved in iron availability and is essential for the plant to complete its biological cycle. In graminaceous plants, NA is also the precursor in the biosynthesis of phytosiderophores. Arabidopsis lines accumulating 4- and 100-fold more NA than wild-type plants were used in order to evaluate the impact of such an NA overaccumulation on iron homeostasis. The expression of iron-regulated genes including the IRT1/FRO2 iron uptake system is highly induced at the transcript level under both iron-sufficient and iron-deficient conditions. Nevertheless, NA overaccumulation does not interfere with the iron uptake mechanisms since the iron levels are similar in the NA-overaccumulating line and wild-type plants in both roots and leaves under both sufficient and deficient conditions. This observation also suggests that the translocation of iron from the root to the shoot is not affected in the NA-overaccumulating line. However, NA overaccumulation triggers an enhanced sensitivity to iron starvation, associated with a decrease in iron availability. This study draws attention to a particular phenotype where NA in excess paradoxically leads to iron deficiency, probably because of an increase of the NA apoplastic pool sequestering iron. This finding strengthens the notion that extracellular NA in the apoplast could be a major checkpoint to control plant iron homeostasis.
 ...
PMID:Increased sensitivity to iron deficiency in Arabidopsis thaliana overaccumulating nicotianamine. 1918 76

Nicotianamine (NA) is a metabolite synthesized by all plants, in which it is involved in the homeostasis of different micronutrients such as iron, nickel or zinc. In some plants it also serves as a precursor of phytosiderophores, which are used for extracellular iron scavenging. Previous studies have also established the presence of NA in filamentous fungi and some mosses, whereas an analogue of NA was inferred in an archaeon. More recently, opine-type metallophores with homology to NA were uncovered in bacteria, especially in human pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa or Yersinia pestis, synthesizing respectively staphylopine, pseudopaline and yersinopine. Here, we review the current state of knowledge regarding the discovery, biosynthesis, function and regulation of these metallophores. We also discuss the genomic environment of the cntL gene, which is homologous to the plant NA synthase (NAS) gene, and plays a central role in the synthesis of NA-like metallophores. This reveals a large diversity of biosynthetic, export and import pathways. Using sequence similarity networks, we uncovered that these metallophores are widespread in numerous bacteria thriving in very different environments, such as those living at the host-pathogen interface, but also in the soil. We additionally established a phylogeny of the NAS/cntL gene and, as a result, we propose that this gene is an ancient gene and NA, or its derivatives, is an ancient metallophore that played a prominent role in metal acquisition or metal resistance. Indeed, our phylogenetic analysis suggests an evolutionary model where the possibility to synthesize this metallophore was present early in the appearance of life, although it was later lost by most living microorganisms, unless facing metal starvation such as at the host-pathogen interface or in some soils. According to our model, NA then re-emerged as a central metabolite for metal homeostasis in fungi, mosses and all known higher plants.
 ...
PMID:The ancient roots of nicotianamine: diversity, role, regulation and evolution of nicotianamine-like metallophores. 3308 6