In silico characterization of a nitrate reductase gene family and analysis of the predicted proteins from the moss Physcomitrella patens

Abstract

Assimilatory nitrate reductase (NR; EC 1.7.1.1-3) catalyzes the reduction of nitrate to nitrite. This enzyme has a conserved structure common to fungi, algae and plants. However, some differences in the amino acid sequence between plant and algal NR suggest that the activity regulation mechanisms have changed during plant evolution. Since only NRs from angiosperms have been studied, the search and analysis of NR genes and proteins from the moss Physcomitrella patens, a basal land plant, was performed to widen the knowledge of land plant NR structure. A family of three nr genes, named ppnia1;1, ppnia1;2 and ppnia2, was localized in the P. patens genome. The predicted proteins are canonical NRs with the conserved domains Molybdene-Cytochorme b –Cytochrome b reductase and possess 20 amino acid residues important for the enzymatic function conserved in plant and algal NRs. Interestingly, moss NRs lack a consensus sequence, common to angiosperm NRs, that is a target for posttranslational regulation. A phylogenetic tree with embryophyte and green algae NR sequences was constructed and P. patens NRs localized at the base of embryophyte NR evolution. The data presented here suggest that bryophytes and vascular plants have different systems to regulate NR activity.

Keywords: :

• Physcomitrella patens
• basal embryophytes
• nitrate reductase
• posttranslational regulation

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

Authors are grateful to an anonymous reviewer and editor in chief of CIB for they enlighten comments that help us to improve this work. Also we want to thank to Dr. Jorge Luis Folch Mallol and Dr. Ernesto Ortiz Suri for they helpful comments to this manuscript.