A natriuretic peptide from Arabidopsis thaliana (AtPNP-A) can modulate catalase 2 activity

Abstract

Analogues of vertebrate natriuretic peptides (NPs) present in plants, termed plant natriuretic peptides (PNPs), comprise a novel class of hormones that systemically affect salt and water balance and responses to plant pathogens. Several lines of evidence indicate that Arabidopsis thaliana PNP (AtPNP-A) affects cellular redox homeostasis, which is also typical for the signaling of its vertebrate analogues, but the molecular mechanism(s) of this effect remains elusive. Here we report identification of catalase 2 (CAT2), an antioxidant enzyme, as an interactor of AtPNP-A. The full-length AtPNP-A recombinant protein and the biologically active fragment of AtPNP-A bind specifically to CAT2 in surface plasmon resonance (SPR) analyses, while a biologically inactive scrambled peptide does not. In vivo bimolecular fluorescence complementation (BiFC) showed that CAT2 interacts with AtPNP-A in chloroplasts. Furthermore, CAT2 activity is lower in homozygous atpnp-a knockdown compared with wild type plants, and atpnp-a knockdown plants phenocopy CAT2-deficient plants in their sensitivity to elevated H2O2, which is consistent with a direct modulatory effect of the PNP on the activity of CAT2 and hence H2O2 homeostasis. Our work underlines the critical role of AtPNP-A in modulating the activity of CAT2 and highlights a mechanism of fine-tuning plant responses to adverse conditions by PNPs.

Arabidopsis Plant Natriuretic Peptide Is a Novel Interactor of Rubisco Activase

“…It is important to note that RCA has been previously identified as a strong interactor of the AtPNP-A protein (lacking the signal peptide) in the Yeast Two-Hybrid assay [ 24 ], which is in accordance with our kinetic analyses. Furthermore, RCA was also proposed as a putative binding partner of pAtPNP-A based on cross-linking experiments performed in MCPs, followed by affinity chromatography and mass spectrometric identification [ 24 , 26 ]. Finally, our recent study indicates AtPNP-A localizes into chloroplasts [ 24 ], which may further support potential biological relevance of its interaction with a stromal RCA protein.…”

“…Furthermore, RCA was also proposed as a putative binding partner of pAtPNP-A based on cross-linking experiments performed in MCPs, followed by affinity chromatography and mass spectrometric identification [ 24 , 26 ]. Finally, our recent study indicates AtPNP-A localizes into chloroplasts [ 24 ], which may further support potential biological relevance of its interaction with a stromal RCA protein. Although the data reported here are of preliminary nature and the biological significance of this interaction is still to be elucidated, this increasing body of evidence has potential implications of the interaction between PNPs and RCA for plant development and stress responses.…”

“…In analogy to vertebral natriuretic peptides, many effects exerted by PNPs involve rapid increases in 3′,5′-cyclic guanosine monophosphate (cGMP) [ 14 , 23 ]. A growing body of evidence indicates that reactive oxygen species (ROS) are also second messengers in the transduction of AtPNP-A signals [ 4 , 24 ]. Despite extensive efforts to elucidate molecular mechanism of AtPNP-A action over the last decade, only a handful of its interactors, including receptors [ 16 , 25 ], have been identified [ 26 ] and characterized [ 24 ].…”

Computational Identification of Functional Centers in Complex Proteins: A Step-by-Step Guide With Examples

“…(Swiezawska et al, 2015(Swiezawska et al, , 2017 and Japanese morning glory (Szmidt-Jaworska et al, 2009) and in the monocot grass model Brachypodium (Swiezawska et al, 2020), as well as in a human immune-responsive protein IRAK3 (Freihat et al, 2019), have demonstrated the robustness of this approach and its significance in biological discoveries across different systems. Furthermore, the method enables candidate selections for follow-up in vivo and in planta studies that will eventually reveal the biological roles of these functional centers such as those reported in Joudoi et al (2013), Shen et al (2019), Vaz Dias et al (2019, Angkawijaya et al (2020), Lee et al (2020), andTurek et al (2020). We foresee that emerging experimental data will inform and strengthen motif refinement efforts, and enable the development of modern machine learning techniques that incorporate multiple features ranging from the classical physicochemical properties of protein domains and protein-protein interaction (PPI) networks to GO based function predictions, to not only automate annotations for uncharacterized proteins, but also to identify hidden functional centers in complex multi-functional proteins (Rifaioglu et al, 2019;Bonetta and Valentino, 2020;Cai et al, 2020;Littmann et al, 2021).…”

Amino acid motifs for the identification of novel protein interactants

“…The PNP-binding site (green), the ABA-binding site (blue), and the H-NOX center (orange) are represented, with the key amino acids involved in interactions with their ligands shown in dark grey. The PNP-binding site is implicated in H 2 O 2 homeostasis, regulation of protoplast volume, defense response against pathogens, and photosynthesis, which could be achieved through interactions of PNP-A (TAIR: At2g18660) with PNP-receptor 1 (TAIR: At1g33612), catalase 2 (TAIR: At4g35090) or Rubisco activase (TAIR: At2g39730) [106] , [107] , [108] , [109] , [110] . The ABA-binding site of an outward rectifying potassium channel AtGORK (TAIR: At5g37500) is involved in K + transport in guard cells [95] .…”