Functional characterization of an Arabidopsis prolyl aminopeptidase AtPAP1 in response to salt and drought stresses

A mitochondrial prolyl aminopeptidase PAP2 releases N‐terminal proline and regulates proline homeostasis during stress response

“…Sequence analysis reveals that PAP2 shares a conserved Ser-His-Asp catalytic triad and S33 protein family fingerprint motifs to PAP1 (Figure 1c), as previously characterised in Arabidopsis PAP homologue (Sun et al, 2013), that is evolutionarily distant to PAP2 (Figure 1a). Sun et al (2013) had showed that the shorter isoform of PAP1 (At2g14260.2, 329 aa) is localised to the cytosol as determined by biolistic transformation of onion epidermal cells. However, the longer isoform of PAP1 (At2g14260.1, 380 aa; Figure 1c) is predicted to contain a putative chloroplast targeting peptide ( Figure S1).…”

“…Arabidopsis contains two PAP homologues, PAP1 (At2g14260) and PAP2 (At3g61540), where one homologue PAP1 has been previously characterised (Sun et al, 2013). Based on sequence homology, all queried plant species contain two PAP homologues that are homologous to Arabidopsis PAP1 and PAP2, as well as moss Physcomitrella patens and the green algae Chlamydomonas reinhardtii (Figure 1a).…”

“…Proline accumulation has been associated with tolerance to a range of abiotic stresses (Yoshiba et al, 1995;Choudhary et al, 2005). Additionally, PAP homologues in plants were previously identified to have a role in conferring tolerance to various abiotic stresses (Sun et al, 2013;Wang et al, 2015a). To investigate the potential role of PAP2 in the plant stress response, we examined pap2-1 and pap2-2 under salt and drought stress during vegetative growth (Figure 5a).…”

“…Bacterial PAP primarily targets smaller peptides of up to 12 aa long, whereby its activity decreases with longer peptides (Ito et al, 2013). Overexpression of an Arabidopsis PAP1 isoform (At2g14260.2) resulted in an increase of accumulated free proline in leaf tissues, and a higher tolerance to drought and high salinity stresses (Sun et al, 2013). Similarly, overexpression of wheat (Triticum aestivum) PAP in Arabidopsis increased the level of accumulated proline in leaf that enhances survival rate and biomass of plants following zinc chloride (ZnCl 2 ) exposure (Wang et al, 2015a).…”

Identification of key genes involved in the phenotypic alterations of res (restored cell structure by salinity) tomato mutant and its recovery induced by salt stress through transcriptomic analysis

“…We found remarkable expression differences between WT and res plants, in both tissues and treatments, for genes related to protein metabolism, especially those encoding proteases and PIs (Table 5 ). PIs have been generally associated to biotic stress responses [ 37 ], although they also seem to play important roles in abiotic stress responses, as adaptation to stress requires the active balance between regulated proteolysis and inhibition of uncontrolled proteolysis [ 38 ]. The overexpression of a cysteine protease inhibitor from Jatropha curcas in transgenic Nicotiana benthamiana conferred increased salinity tolerance along with lower MDA contents [ 39 ].…”