Proline biosynthesizing enzymes (glutamate 5-kinase and pyrroline-5-carboxylate reductase) from a model cyanobacterium for desiccation tolerance

Abstract

Drought is the most important abiotic stress, challenging sustainable agriculture globally. For desiccation being the multigenic trait, a combination of identified genes from the appropriate organism may render crop tolerant to the water stress. Among the compatible solutes, proline plays multifaceted role in counteracting such stress. The genes encoding proline biosynthesizing enzymes, glutamate 5-kinase (G5K), and pyrroline-5-carboxylate reductase (P5CR) from the low-desiccation-tolerant cyanobacterium Anabaena sp. PCC 7120, were cloned and overexpressed in Escherichia coli BL21(DE3) individually. The recombinant E. coli cells harboring G5K, failed to exhibit enhanced desiccation tolerance relative to those with P5CR that showed increased growth/survival over the wild type. This may be ascribed to the overexpression of the reductase gene. Multiple sequence alignment showed P5CR to be conserved in all the organisms. We hypothesize that P5CR gene from high-desiccation-tolerant cyanobacteria may be adopted as the candidate for making transgenic N 2 -fixing cyanobacterium for paddy fields and/or crop development in future.

The novel regulatory ncRNA, NfiS, optimizes nitrogen fixation via base pairing with the nitrogenase gene nifK mRNA in Pseudomonas stutzeri A1501

“…S4B). The proC gene encodes pyrroline carboxylate reductase, a key enzyme in the last step in proline biosynthesis, and katA encodes catalase, both of which play important roles in oxidative or osmotic stress responses (33,34). Based on these studies, NfiS likely controls nitrogenase activity at the transcriptional level through the regulation of both the RpoN/NtrC/NifA regulatory cascade and certain stress response-related genes via unknown mechanisms.…”

Transcript expression profiling in two contrasting cultivars and molecular cloning of a SKP-1 like gene, a component of SCF-ubiquitin proteasome system from mungbean Vigna radiate L.

“…Candidate genes which have been explored till date in legumes are involved in combating stress by augmenting the level of compatible solutes like proline, starch, sugars etc. 2 . This, in turn, shields the plant by cellular osmotic adjustment, detoxification of ROS, protection of membrane integrity and stabilization of enzymes/proteins 3,4 .…”

N-Alkyl-α-amino acids in Nature and their biocatalytic preparation

“…Pyrroline-5-carboxylate reductases (P5CRs, EC 1.5.1.2) are a class of enzymes involved in the biosynthesis of proline, which is formed following reduction of pyrroline-5-carboxylate (Singh et al, 2013). They are perhaps the least characterised of the oxido-reductases described in this chapter in spite of their substrate similarity to that of NMAADHs and KIREDs (Yura, 1959).…”