Roles of Plant Proteases in Pathogen Defense (original) (raw)
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Indispensable Role of Proteases in Plant Innate Immunity
International Journal of Molecular Sciences, 2018
Plant defense is achieved mainly through the induction of microbe-associated molecular patterns (MAMP)-triggered immunity (MTI), effector-triggered immunity (ETI), systemic acquired resistance (SAR), induced systemic resistance (ISR), and RNA silencing. Plant immunity is a highly complex phenomenon with its own unique features that have emerged as a result of the arms race between plants and pathogens. However, the regulation of these processes is the same for all living organisms, including plants, and is controlled by proteases. Different families of plant proteases are involved in every type of immunity: some of the proteases that are covered in this review participate in MTI, affecting stomatal closure and callose deposition. A large number of proteases act in the apoplast, contributing to ETI by managing extracellular defense. A vast majority of the endogenous proteases discussed in this review are associated with the programmed cell death (PCD) of the infected cells and exhibit caspase-like activities. The synthesis of signal molecules, such as salicylic acid, jasmonic acid, and ethylene, and their signaling pathways, are regulated by endogenous proteases that affect the induction of pathogenesis-related genes and SAR or ISR establishment. A number of proteases are associated with herbivore defense. In this review, we summarize the data concerning identified plant endogenous proteases, their effect on plant-pathogen interactions, their subcellular localization, and their functional properties, if available, and we attribute a role in the different types and stages of innate immunity for each of the proteases covered.
The plant proteolytic machinery and its role in defence
Current Opinion in Plant Biology, 2004
The diverse roles of plant proteases in defence responses that are triggered by pathogens or pests are becoming clearer. Some proteases, such as papain in latex, execute the attack on the invading organism. Other proteases seem to be part of a signalling cascade, as indicated by protease inhibitor studies. Such a role has also been suggested for the recently discovered metacaspases and CDR1. Some proteases, such as RCR3, even act in perceiving the invader. These exciting recent reports are probably just the first examples of what lies beneath. More roles for plant proteases in defence, as well as the regulation and substrates of these enzymes, are waiting to be discovered.
The International Journal of Biochemistry & Cell Biology, 2003
Plants have evolved efficient mechanisms to resist pathogens. The earliest defense response is the hypersensitive response (HR) considered as the main step leading to plant systemic acquired resistance (SAR) that protects the whole plant against a large spectrum of pathogens. We showed previously that elicitation of defense reactions in tobacco cells by cryptogein, a proteinaceous elicitor of plant defense reactions, leads to a rapid and differential accumulation of transcripts corresponding to genes encoding defense-induced (din) subunits of 20S proteasome: 1din, ␣3din and ␣6din.
Frontiers in plant science, 2015
Upon host penetration, fungal pathogens secrete a plethora of effectors to promote disease, including proteases that degrade plant antimicrobial proteins, and protease inhibitors (PIs) that inhibit plant proteases with antimicrobial activity. Conversely, plants secrete proteases and PIs to protect themselves against pathogens or to mediate recognition of pathogen proteases and PIs, which leads to induction of defense responses. Many examples of proteases and PIs mediating effector-triggered immunity in host plants have been reported in the literature, but little is known about their role in compromising basal defense responses induced by microbe-associated molecular patterns. Recently, several reports appeared in literature on secreted fungal proteases that modify or degrade pathogenesis-related proteins, including plant chitinases or PIs that compromise their activities. This prompted us to review the recent advances on proteases and PIs involved in fungal virulence and plant defen...
Plant protease inhibitors: a defense strategy in plants
Biotechnology and Molecular Biology …, 2007
Proteases, though essentially indispensable to the maintenance and survival of their host organisms, can be potentially damaging when overexpressed or present in higher concentrations, and their activities need to be correctly regulated. An important means of regulation involves modulation of their activities through interaction with substances, mostly proteins, called protease inhibitors. Some insects and many of the phytopathogenic microorganisms secrete extracellular enzymes and, in particular, enzymes causing proteolytic digestion of proteins, which play important roles in pathogenesis. Plants, however, have also developed mechanisms to fight these pathogenic organisms. One important line of defense that plants have to fight these pathogens is through various inhibitors that act against these proteolytic enzymes. These inhibitors are thus active in endogenous as well as exogenous defense systems. Protease inhibitors active against different mechanistic classes of proteases have been classified into different families on the basis of significant sequence similarities and structural relationships. Specific protease inhibitors are currently being overexpressed in certain transgenic plants to protect them against invaders. The current knowledge about plant protease inhibitors, their structure and their role in plant defense is briefly reviewed.
Proteasomal degradation in plant-pathogen interactions
Seminars in cell & …, 2009
The ubiquitin/26S proteasome pathway is a basic biological mechanism involved in the regulation of a multitude of cellular processes. Increasing evidence indicates that plants utilize the ubiquitin/26S proteasome pathway in their immune response to pathogen ...
Defense and Offense Strategies: The Role of Aspartic Proteases in Plant–Pathogen Interactions
Biology, 2021
Plant aspartic proteases (APs; E.C.3.4.23) are a group of proteolytic enzymes widely distributed among different species characterized by the conserved sequence Asp-Gly-Thr at the active site. With a broad spectrum of biological roles, plant APs are suggested to undergo functional specialization and to be crucial in developmental processes, such as in both biotic and abiotic stress responses. Over the last decade, an increasing number of publications highlighted the APs’ involvement in plant defense responses against a diversity of stresses. In contrast, few studies regarding pathogen-secreted APs and AP inhibitors have been published so far. In this review, we provide a comprehensive picture of aspartic proteases from plant and pathogenic origins, focusing on their relevance and participation in defense and offense strategies in plant–pathogen interactions.
Plant Immunity and Pathogen Interfering Mechanisms: Effectors and Bodyguards
2017
There is an arm race between plants and their pathogens, by fungi, and bacteria, as well as between plants and insects. Plant proteases are hydrolytic enzymes, grouped on the basis of the catalytic amino acid, as serine, cysteine, aspartic acid, or metal dependent activity. Plant-fungi interactions, as well as plants with other invaders, have been elucidated in recent years, showing an evolutionary adaptation of hosts and invaders to produce proteases and evolve new protease inhibitors. Interactions between protease inhibitors and the target proteases provide information on the ways organisms interact and defend themselves from pathogens, recognizing symbionts from parasite organisms. A comparative analysis of protease inhibitors in plants with sequenced genomes have been recently performed. In the analysis of PIs, protease biochemical assays, protein-protein interaction studies and protease chips were used to analyze constitutive and inducible inhibitors under different conditions....
Intracellular Proteases and Resistance in Plants
In order to understand the potential role of intracellular proteolytic enzymes in the mechanism of herbicide and insect resistance in plants, we have compared the levels of activity of a representative range of protease types (acid, neutral & alkaline proteinases & peptidases) in plant tissues from herbicide resistant and susceptible biotypes of the weed species Chenopodium album, Amaranthus retroflexus and Lolium rigidum and insect resistant (Rathu Heenati) and susceptible (TN1) cultivars of rice (Oryza sativa). The activities of many protease types were significantly higher (typically by 1.5-3 fold) in both herbicide and insect resistant plant cultivars, suggesting that these enzymes may play a significant role in the defence against stress in plants.
Protective Roles of Cytosolic and Plastidal Proteasomes on Abiotic Stress and Pathogen Invasion
Plants
Protein malfunction is typically caused by abiotic stressors. To ensure cell survival during conditions of stress, it is important for plant cells to maintain proteins in their respective functional conformation. Self-compartmentalizing proteases, such as ATP-dependent Clp proteases and proteasomes are designed to act in the crowded cellular environment, and they are responsible for degradation of misfolded or damaged proteins within the cell. During different types of stress conditions, the levels of misfolded or orphaned proteins that are degraded by the 26S proteasome in the cytosol and nucleus and by the Clp proteases in the mitochondria and chloroplasts increase. This allows cells to uphold feedback regulations to cellular-level signals and adjust to altered environmental conditions. In this review, we summarize recent findings on plant proteolytic complexes with respect to their protective functions against abiotic and biotic stressors.