Phytepsin, a barley vacuolar aspartic proteinase, is highly expressed during autolysis of developing tracheary elements and sieve cells

Runeberg-Roos, Pia; Saarma, Märt

doi:10.1046/j.1365-313x.1998.00187.x

Cited by 67 publications

(39 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Plant aspartic proteases have been implicated in a variety of physiological processes where cell death events play a key role (7,(22)(23)(24)(25). Activation of these proteases therefore triggers the onset of these events and determines the fate of the plant cell.…”

Section: Discussionmentioning

confidence: 99%

Activation, Proteolytic Processing, and Peptide Specificity of Recombinant Cardosin A

Castanheira

Samyn

Sergeant

et al. 2005

Journal of Biological Chemistry

View full text Add to dashboard Cite

Cardosins are model plant aspartic proteases, a group of proteases that are involved in cell death events associated with plant senescence and stress responses. They are synthesized as single-chain zymogens, and subsequent conversion into two-chain mature enzymes is a crucial step in the regulation of their activity. Here we describe the activation and proteolytic processing of recombinant procardosin A. The cleavage sites involved in this multi-step autocatalytic process were determined, some of them using a novel method for C-terminal sequence analysis. Even though the two-chain recombinant enzyme displayed similar properties as natural cardosin A, a single-chain mutant form was engineered based on the processing results and produced in Escherichia coli. Determination of its primary specificity using two combinatorial peptide libraries revealed that this mutant form behaved like the natural enzyme. The primary specificity of the enzyme closely resembles those of cathepsin D and plasmepsins, suggesting that cardosin A shares the same peptide scissile bond preferences of its vacuolar/lysosomal mammalian and protozoan homologues.Sequencing of the Arabidopsis genome unveiled over 50 genes coding for aspartic proteases of the pepsin type (1, 2). These genes have been assigned to three different categories: typical, nucellin-like, and atypical proteases (2). With the exception of the products of cnd41 (3-5) and cdr1 (6) genes, very little is known about the nucellin and the atypical subgroups. In fact, most of the knowledge acquired during the last decade relates to the typical subgroup of plant aspartic proteases and has been generated predominantly from the study of phytepsin from barley seeds and cardosins from the flowers of cardoon (7).Typical plant aspartic proteases constitute a set of enzymes that share many structural and functional features not only among them but also with some of their mammalian and microbial homologues. They display activity at acidic pH and are inhibited by pepstatin A, a natural hexapeptide from Streptomyces. Common features also include the overall three-dimensional structure of mature enzymes, the catalytic apparatus, and a conserved DT/SG motif. A distinguishing feature of typical plant aspartic proteases is the occurrence of an extra 100-amino acid-long internal segment, known as the plant-specific insert (PSI), in the sequence of their precursors. This domain displays structural and functional similarities to saposins (8, 9), sphingolipid-activating proteins from animals, and some antimicrobial peptides such as NK-lysin, granulysin, and amoebapores (10); it folds as an independent domain in the precursor form (11) and is subsequently excised to generate the mature two-chain form (7). Even though the function of PSI 1 is not yet fully elucidated, it seems to play an important role in targeting plant aspartic protease precursors to the vacuole (11,12).Little is known regarding the function of typical plant aspartic proteases. Colocalization studies with putative substrates and thei...

show abstract

Section: Discussionmentioning

confidence: 99%

Activation, Proteolytic Processing, and Peptide Specificity of Recombinant Cardosin A

Castanheira

Samyn

Sergeant

et al. 2005

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Saposin-like proteins like NK-lysin, granulysin, and amoebapores are known for their antimicrobial activities (12,15,33), and granulysin has also been implicated in apoptotic mechanisms (34). On the other hand, plant aspartic proteinases such as phytepsin (35), nucellin (36), and cardosin B (37) have been found in tissues undergoing programmed cell death. It is possible therefore that the vesicle leakage of PSI may function as part of a defensive mechanism against pathogens and as an effector of cell death.…”

Section: Discussionmentioning

confidence: 99%

The Saposin-like Domain of the Plant Aspartic Proteinase Precursor Is a Potent Inducer of Vesicle Leakage

Egas¹,

Lavoura²,

Resende³

et al. 2000

Journal of Biological Chemistry

View full text Add to dashboard Cite

A unique feature of plant aspartic proteinase precursors is the presence of an internal domain, known as plant-specific insert, whose function is not completely understood. The three-dimensional structure of the plant-specific insert resembles that of saposin-like proteins, a group of lipid-binding proteins involved in a variety of physiological processes. Here we show that recombinant plant-specific insert is able to interact with phospholipid vesicles and to induce leakage of their contents in a pH-and lipid-dependent manner. The leakage activity is higher at pH 4.5 and requires the presence of acidic phospholipids such as phosphatidylserine. To determine whether the same effect could be observed when the plant-specific insert is part of the precursor form, procardosin A and a mutant form lacking this specific domain were produced and characterized. Procardosin A displays a similar activity profile, whereas the mutant without the plant-specific insert shows only residual activity. These findings indicate that the plant-specific insert domain of plant aspartic proteinases mediates an interaction of their precursors with phospholipid membranes and induces membrane permeabilization. It is therefore possible that the plantspecific insert, alone or in conjunction with the proteolytic activity of plant aspartic proteinases, may function either as a defensive weapon against pathogens or in late autolysis of plant cells.Plant aspartic proteinases have been purified and characterized from several species. They share high sequence and structure homology, as well as general biochemical properties, with the animal and microbial aspartic proteinases (1). A unique feature present in most aspartic proteinases of plant origin is an extra protein domain of about 100 amino acids, generally named plant-specific insert (PSI) 1 , that has no homology to any other aspartic protease sequence (2). The PSI is present in the precursors of plant aspartic proteinases but is absent from the mature form of the enzymes (2-6). The function of this plantspecific insert is still unclear. An important role in the vacuolar targeting of aspartic proteinase precursors has been proposed, either by its direct interaction with the membrane, where it would act as a targeting signal (4), or by the interaction of a putative membrane binding region, formed by a cluster of the mature protein and the PSI in prophytepsin, with the membrane itself or with a receptor in the Golgi apparatus (7). It has been suggested (8) that the PSI would interact with the membrane probably in the endoplasmic reticulum as a prerequisite for signaling plant aspartic proteases into the vacuole, because previous work identified a putative vacuolar targeting sequence on the C terminal end of the aspartic protease of cardoon (5). On the other hand, the PSI could be implicated in the correct folding of the enzyme, as suggested by the lack of activation of a mutant of recombinant procyprosin bearing a deletion of the PSI sequence (2).The plant-specific insert bears high homology wit...

show abstract

“…PCD also has been associated with several processes in plants, including senescence (Bleecker and Patterson, 1997;Miller et al, 1999;Schmid et al, 2001), stress (Katsuhara, 1997;Solomon et al, 1999), development (Runeberg-Roos and Saarma, 1998;Groover and Jones, 1999;Schmid et al, 1999), and the hypersensitive response (HR) to pathogens (Dangl et al, 1996;Mittler et al, 1997;Pontier et al, 1998;Mackey et al, 2002;Abramovitch et al, 2003). Currently, very little is known about the fundamental processes that control and regulate PCD in plants.…”

Section: Introductionmentioning

confidence: 99%

“…Studies have described proteases associated with several types of plant PCD, including senescence (Delorme et al, 2000;Schmid et al, 2001;Eason et al, 2002), oxidative stress (Solomon et al, 1999), seed development (Schmid et al, 1998(Schmid et al, , 1999Wan et al, 2002), tracheary element development (Runeberg-Roos and Saarma, 1998;Groover and Jones, 1999), and the HR (Vera and Conejero, 1988;D'Silva et al, 1998;Krü ger et al, 2002). However, characterization of these proteases reveals that they are degradative, not processive enzymes; thus, they are unlike caspases or other proteases involved in signaling pathways.…”

Section: Introductionmentioning

confidence: 99%

Purification and Characterization of Serine Proteases That Exhibit Caspase-Like Activity and Are Associated with Programmed Cell Death in Avena sativa

2004

View full text Add to dashboard Cite

Victoria blight of Avena sativa (oat) is caused by the fungus Cochliobolus victoriae, which is pathogenic because of the production of the toxin victorin. The victorin-induced response in sensitive A. sativa has been characterized as a form of programmed cell death (PCD) and displays morphological and biochemical features similar to apoptosis, including chromatin condensation, DNA laddering, cell shrinkage, altered mitochondrial function, and ordered, substrate-specific proteolytic events. Victorin-induced proteolysis of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is shown to be prevented by caspase-specific and general protease inhibitors. Evidence is presented for a signaling cascade leading to Rubisco proteolysis that involves multiple proteases. Furthermore, two proteases that are apparently involved in the Rubisco proteolytic cascade were purified and characterized. These proteases exhibit caspase specificity and display amino acid sequences homologous to plant subtilisin-like Ser proteases. The proteases are constitutively present in an active form and are relocalized to the extracellular fluid after induction of PCD by either victorin or heat shock. The role of the enzymes as processive proteases involved in a signal cascade during the PCD response is discussed.

show abstract

Phytepsin, a barley vacuolar aspartic proteinase, is highly expressed during autolysis of developing tracheary elements and sieve cells

Cited by 67 publications

References 46 publications

Activation, Proteolytic Processing, and Peptide Specificity of Recombinant Cardosin A

Activation, Proteolytic Processing, and Peptide Specificity of Recombinant Cardosin A

The Saposin-like Domain of the Plant Aspartic Proteinase Precursor Is a Potent Inducer of Vesicle Leakage

Purification and Characterization of Serine Proteases That Exhibit Caspase-Like Activity and Are Associated with Programmed Cell Death in Avena sativa

Contact Info

Product

Resources

About