Crucial Role of Antioxidant Proteins and Hydrolytic Enzymes in Pathogenicity of Penicillium expansum

Abstract

Penicillium expansum, a widespread filamentous fungus, is a major causative agent of fruit decay and may lead to the production of mycotoxin that causes harmful effects on human health. In this study, we compared the cellular and extracellular proteomes of P. expansum in the absence and presence of borate, which affects the virulence of the fungal pathogen. The differentially expressed proteins were identified using ESI-Q-TOF-MS/MS. Several proteins related to stress response (glutathione S-transferase, catalase, and heat shock protein 60) and basic metabolism (glyceraldehyde-3-phosphate dehydrogenase, dihydroxy-acid dehydratase, and arginase) were identified in the cellular proteome. Catalase and glutathione S-transferase, the two antioxidant enzymes, exhibited reduced levels of expression upon exposure to borate. Because catalase and glutathione S-transferase are related to oxidative stress response, we further investigated the reactive oxygen species (ROS) levels and oxidative protein carbonylation (damaged proteins) in P. expansum. Higher amounts of ROS and carbonylated proteins were observed after borate treatment, indicating that catalase and glutathione S-transferase are important in scavenging ROS and protecting cellular proteins from oxidative damage. Additionally to find secretory proteins that contribute to the virulence, we studied the extracellular proteome of P. expansum under stress condition with reduced virulence. The expression of three protein spots were repressed in the presence of borate and identified as the same hydrolytic enzyme, polygalacturonase.

Fruit ripening mutants reveal cell metabolism and redox state during ripening

“…Previous studies has shown the increased levels of H 2 O 2 in peach (Qin et al 2009), muskmelon (Lacan and Baccou 1998), and tomato (Jimenez et al 2002) fruits. It is also reported that fruit senescence can be reduced by lowering reactive oxygen species (ROS) content by decreasing oxygen concentration in storage environment, whereas H 2 O 2 enhances senescence of fruits (Tian et al 2004;Qin et al 2007). Moreover, high level of oxygen also increases the level of H 2 O 2 in mitochondria (Turrens et al 1982) and affects the antioxidant enzymes activity in fruit and accelerates fruit senescence (Wang et al 2005).…”

Exogenous Calcium Improves Viability of Biocontrol Yeasts Under Heat Stress by Reducing ROS Accumulation and Oxidative Damage of Cellular Protein

“…1b). As high amounts of ROS usually lead to increased levels of carbonylated proteins in yeast cells [19], a high level of carbonylated proteins were also detected in the D. hansenii cells, and adding exogenous calcium could markedly reduce the protein carbonylation of the yeasts (Fig. 3a, b).…”

Effect of inoculum size of yeastDebaryomyces hanseniito controlPenicillium italicumon Mexican lime (Citrus aurantiifolia) during storage

“…Torres et al (2006) report that variations in the adaptability of yeasts to particular fruit are an important factor in reducing colonization of fungal pathogens, while concentration of yeast inoculum perhaps influences competition for space and nutrients, thereby reducing energy sources for germination of spores and mycelium development and reducing infection. Di grak and Ö zc¸elik (2001), Miedes and Lorences (2006), and Qin, Tian, Chan, and Li (2007) remark that P. italicum requires carbon sources for spore germination and production of enzymes, such as b-1,3-and b-1,6-glucanase, which are essential in the process of infecting fruits. There are other mechanisms in yeast to limit growth of P. italicum.…”