The 2·5 Å Structure of Pokeweed Antiviral Protein

Monzingo, A.F.; Collins, Edward J.; Ernst, S.R.; Irvin, James D.; Robertus, Jon D.

doi:10.1006/jmbi.1993.1547

Cited by 118 publications

(97 citation statements)

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“…The t&dimensional structure of PAP II is not known, however, the superposition of the X-ray structures of the ricin A-chain and PAP revealed a very similar folding pattern with similar positions of key active residues [24]. Therefore, it can be thought that the overall structure and mechanism of the action of PAP II is similar to that of ricin.…”

Section: Sequence Comparisonmentioning

confidence: 98%

Isolation and characterization of a cDNA clone encoding the pokeweed antiviral protein II from Phytolacca americana and its expression in E. coli

1994

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Three distinct ribosome-inactivating proteins (RIPS) were isolated from pokeweed (Phytolacca americana). We identified and sequenced for the first time a complete cDNA encoding the pokeweed antiviral protein II (PAP II), which is expressed in the late summer leaves of pokewecd. The cDNA of PAP II consists of 1,187 nucleotides and encodes a mature protein of 285 amino acids. Its predicted amino acid sequence is only 33% similar to PAP and PAP-S. The NH2 terminal extrapeptide (25 amino acid residues) was similar but not identical to that of PAP's extrapeptide. The cDNA of PAP II was expressed in E. coli. The growth of the transformants was strongly inhibited after induction of the gene. Furthermore, PAP II, which was produced in E. coli, inhibited protein synthesis in a rabbit reticulocyte translation system. Thus, recombinant PAP II would appear to be as functional as native PAP in inhibiting protein synthesis in both prokaryotes and eukaryotes.

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Section: Sequence Comparisonmentioning

confidence: 98%

Isolation and characterization of a cDNA clone encoding the pokeweed antiviral protein II from Phytolacca americana and its expression in E. coli

1994

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“…Taken together with the differential effect of DEPC on the DNase and RNA N-glycosidase activities, the latter seems more reasonable. Furthermore, the active site of PAP lies in a cleft between two domains [33], suggesting that full refolding of both domains would be required to restore N-glycosidase activity. It therefore seems unlikely that such refolding would restore only one of two intrinsic activities.…”

Section: Pap Heat Treatment Of Pap Eliminates Dnase Activity But Notmentioning

confidence: 99%

The deoxyribonuclease activity attributed to ribosome‐inactivating proteins is due to contamination

Day

Lord

Roberts

1998

European Journal of Biochemistry

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The mode of action of ribosome-inactivating proteins (RIPs) has, for many years, been considered to be depurination of a specific adenyl residue of ribosomal RNA, resulting in inhibition of protein synthesis. Recently, this view has been challenged by the observation that many RIP preparations have significant DNase activity in addition to their N-glycosidase activity. In this study, we have investigated the putative DNase activity of two RIPs, ricin and pokeweed antiviral protein (PAP), and show that, in both cases, the DNase activity is due to the presence of contaminating nucleases. The N-glycosidase and DNase activities of PAP were separately and specifically inactivated by chemical modification and heat. Gel filtration of ricin allowed physical separation of the two activities. Furthermore, neither recombinant PAP nor recombinant ricin A-chain purified from Escherichia coli displayed DNase activity.Keywords : deoxyribonuclease; ribosome-inactivating protein; RNA N-glycosidase.Ribosome-inactivating proteins (RIPs) are a group of structurally related proteins which depurinate a specific adenyl residue of 28-S ribosomal RNA (A4324 in rat, [1]). Depurination of this residue prevents binding of elongation factors, thereby inhibiting protein synthesis and resulting in cell death. RIPs can be divided into two classes: type I, which consist of a single subunit possessing RNA N-glycosidase activity, and type II, which have a type I-like catalytic subunit (A chain) linked to a cell-binding subunit (B chain). The B chains of plant toxins, e.g. ricin, are typically galactose/N-acetylgalactosamine-specific lectins and are linked to the A chain via a disulphide bond. Bacterial toxins that catalyse the same depurination reaction as RIPs, e.g. Shiga toxin, have a non-covalently bound glycolipidbinding B-chain pentamer.Most type-II RIPs are potent cytotoxins due to their ability to bind to and enter mammalian cells. Once inside the cell, the toxins exploit the cellular retrograde transport system to reach the endoplasmic reticulum from where they translocate into the cytosol by an as yet undetermined mechanism [2]. As holotoxins show no catalytic activity against ribosomes, separation of the A chain and B chain following intoxication is essential in order to exhibit a toxic effect.Type-I RIPs are, by comparison, only weakly cytotoxic when added exogenously to cells. A number of roles have been proposed for type-I RIPs, including defence mechanisms and promotion of senescence. Those which are active on con-specific ribosomes are typically stored in non-cytosolic compartments or as inactive precursors. Such RIPs are believed to be released into the cytosol following cellular damage, such as that caused by viral infection, resulting in local cell suicide around infected areas. An antifungal role has been proposed for RIPs that are inactive against con-specific ribosomes. Barley RIP is co-expressed with a chitinase, and [1, 3] β glucanase, which, while having intrinsic antifungal activity themselves, also facilitate RIP entry i...

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“…Esta proteína pertence à família das proteínas inibidoras de ribossomo (RIPs) do tipo II (OLSNES, 2004;LORD et al, 1994;. MONZINGO et al, 1993).…”

Section: Introductionunclassified

Influência da concentração de NaCl e pH na extração de ricina em torta de mamona (Ricinus communis L.) e sua caracterização por eletroforese

et al. 2012

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The 2·5 Å Structure of Pokeweed Antiviral Protein

Cited by 118 publications

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Isolation and characterization of a cDNA clone encoding the pokeweed antiviral protein II from Phytolacca americana and its expression in E. coli

Isolation and characterization of a cDNA clone encoding the pokeweed antiviral protein II from Phytolacca americana and its expression in E. coli

The deoxyribonuclease activity attributed to ribosome‐inactivating proteins is due to contamination

Influência da concentração de NaCl e pH na extração de ricina em torta de mamona (Ricinus communis L.) e sua caracterização por eletroforese

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