Structural complexity and functional diversity of plant NADPH oxidases

Abstract

Plant NADPH oxidases also known as respiratory burst oxidase homologs (Rbohs) are a family of membrane-bound enzymes that play diverse roles in the defense response and morphogenetic processes via regulated generation of reactive oxygen species. Rbohs are associated with a variety of functions, although the reason for this is not clear. To evaluate using bioinformatics, the possible mechanisms for the observed functional diversity within the plant kingdom, 127 Rboh protein sequences representing 26 plant species were analyzed. Multiple clusters were identified with gene duplications that were both dicot as well as monocot-specific. The N-terminal sequences were observed to be highly variable. The conserved cysteine (equivalent of Cys890) in C-terminal of AtRbohD suggested that the redox-based modification like S-nitrosylation may regulate the activity of other Rbohs. Three-dimensional models corresponding to the N-terminal domain for Rbohs from Arabidopsis thaliana and Oryza sativa were constructed and molecular dynamics studies were carried out to study the role of Ca in the folding of Rboh proteins. Certain mutations indicated possibly affect the structure and function of the plant NADPH oxidases, thereby providing the rationale for further experimental validation.

Powering the plasma membrane Ca2+-ROS self-amplifying loop

“…This generates a positive feedback loop between generation of ROS and Ca 2+ signals. Conversely, S-nitrosylation of the cysteine residue in the C-terminus was shown to inhibit AtRBOHD activity; as this residue is conserved in the other 18 AtRBOH members, such a regulatory mechanism may be hypothesized to be universal for the family ( Kaur et al , 2018 ). In Arabidopsis, NO generation is rapidly stimulated by H 2 O 2 , so it is tempting to think that this mechanism may serve as a feedback loop, terminating the RBOH-generated ROS signal.…”

Comprehensive Analysis of Respiratory Burst Oxidase Homologs (Rboh) Gene Family and Function of GbRboh5/18 on Verticillium Wilt Resistance in Gossypium barbadense

“…Ten and nine Rbohs have been identified from Arabidopsis and rice, referred to as AtRbohA–AtRbohJ and OsRbohA–OsRbohI, respectively ( Torres et al, 1998 ). Previous studies suggest they have distinct spatio-temporal expression, enzyme activity, and functional diversification ( Lin et al, 2009 ; Kaur and Pati, 2018 ; Kaur et al, 2018 ; Kaya et al, 2019 ). AtrbohB fulfills important roles in the germination of Arabidopsis seeds through variant splicing transcripts ( Muller et al, 2009 ).…”

A point mutation in LTT1 enhances cold tolerance at the booting stage in rice

“…Plant respiratory burst oxidase homologs, also known as NADPH oxidases, are the most crucial enzymes in ROS-producing system (Ben Rejeb et al, 2015;Marino, Dunand, Puppo, & Pauly, 2012;Suzuki et al, 2011). The rice genome contains nine Rbohs (Kaur et al, 2018), we found that except the three genes of OsRboh6, OsRboh8, and OsRboh9, the other six OsRbohs showed significantly enhanced expression in the anthers of ltt1 ( Figure 4a), which should be largely responsible for the over accumulated ROS in the mutant.…”