Sweet Pepper (Capsicum annuum L.) Fruits Contain an Atypical Peroxisomal Catalase That Is Modulated by Reactive Oxygen and Nitrogen Species

Abstract

During the ripening of sweet pepper (Capsicum annuum L.) fruits, in a genetically controlled scenario, enormous metabolic changes occur that affect the physiology of most cell compartments. Peroxisomal catalase gene expression decreases after pepper fruit ripening, while the enzyme is also susceptible to undergo post-translational modifications (nitration, S-nitrosation, and oxidation) promoted by reactive oxygen and nitrogen species (ROS/RNS). Unlike most plant catalases, the pepper fruit enzyme acts as a homodimer, with an atypical native molecular mass of 125 to 135 kDa and an isoelectric point of 7.4, which is higher than that of most plant catalases. These data suggest that ROS/RNS could be essential to modulate the role of catalase in maintaining basic cellular peroxisomal functions during pepper fruit ripening when nitro-oxidative stress occurs. Using catalase from bovine liver as a model and biotin-switch labeling, in-gel trypsin digestion, and nanoliquid chromatography coupled with mass spectrometry, it was found that Cys377 from the bovine enzyme could potentially undergo S-nitrosation. To our knowledge, this is the first report of a cysteine residue from catalase that can be post-translationally modified by S-nitrosation, which makes it especially important to find the target points where the enzyme can be modulated under either physiological or adverse conditions.

Assessment of Subcellular ROS and NO Metabolism in Higher Plants: Multifunctional Signaling Molecules

“…Figure 4 shows a simple model of the most important ROS metabolism enzymes modulated by NO PTMs. Catalase, exclusively present in peroxisomes, is negatively regulated by both nitration and S-nitrosation [168]. On the other hand, S-nitrosation, which inhibits O 2…”

Antioxidant Profile of Pepper (Capsicum annuum L.) Fruits Containing Diverse Levels of Capsaicinoids

“…The profile of antioxidant enzymes during the ripening process has been investigated in pepper fruits previously but, to our knowledge, no comparisons have been made between varieties with different capsaicinoid contents. Thus, for example, in California-type pepper fruits, it has been reported that the catalase activity decreases as the fruit ripens [79,80] and this event is due to the post-translational modification (PTMs) underwent by the enzyme and promoted by ROS and reactive nitrogen species (RNS) derived from nitric oxide (NO) [41,81]. In fact, it has been proved that the ripening of pepper fruits is controlled by NO [8,40,80].…”

“…Relevant differences between the transcriptomes from green immature and ripe pepper fruits have been also reported, involving thousands of genes [8,40] and references therein. From a redox viewpoint, it has been found that reactive oxygen species (ROS) metabolism is also affected during fruit ripening, leading to major changes in total soluble reducing equivalents and the antioxidant capacity in fruits [41]. The profile of the major non-enzymatic antioxidants, including ascorbate, glutathione, carotenoids and polyphenols, has been followed during ripening in pepper fruits [4,11,12,[42][43][44][45][46], but less is known on how enzymatic antioxidants evolve with this physiological process.…”

Antioxidant Profile of Pepper (<em>Capsicum annuum</em> L.) Fruits Containing Diverse Levels of Capsaicinoids

“…The profile of antioxidant enzymes during the ripening process has been investigated in pepper fruits previously but, to our knowledge, no comparisons have been made between varieties with different capsaicinoid content. Thus, for example, in California-type pepper fruits it has been reported that the catalase activity decreases as the fruit ripens [80,81] and this event was due to posttranslational modification (PTMs) underwent by the enzyme and promoted by ROS and reactive nitrogen species (RNS) derived from nitric oxide (NO) [42,82]. In fact, it has been proved that ripening of pepper fruits is controlled by NO [8,41,81].…”

“…Relevant differences between the transcriptomes from green immature and ripe pepper fruits have been also reported, involving thousands of genes [8, 41 and references therein]. From a redox view, it has been found that the reactive oxygen species (ROS) metabolism is also affected during fruit ripening, leading to major changes in total soluble reducing equivalents in fruits and the antioxidant capacity [42]. The profile of the major non-enzymatic antioxidants, including ascorbate, glutathione, carotenoids and polyphenols, have been followed during ripening in pepper fruits [4,11,12,[43][44][45], but less is known on how enzymatic antioxidants evolve with this physiological process.…”