Structure and Activity of a Cytosolic Ribosome-Inactivating Protein from Rice (original) (raw)
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Ribosome-Inactivating Proteins from Plants: A Historical Overview
This review provides a historical overview of the research on plant ribosome-inactivating proteins (RIPs), starting from the first studies at the end of eighteenth century involving the purification of abrin and ricin, as well as the immunological experiments of Paul Erlich. Interest in these plant toxins was revived in 1970 by the observation of their anticancer activity, which has given rise to a large amount of research contributing to the development of various scientific fields. Biochemistry analyses succeeded in identifying the enzymatic activity of RIPs and allowed for a better understanding of the ribosomal machinery. Studies on RIP/cell interactions were able to detail the endocytosis and intracellular routing of ricin, thus increasing our knowledge of how cells handle exogenous proteins. The identification of new RIPs and the finding that most RIPs are single-chain polypeptides, together with their genetic sequencing, has aided in the development of new phylogenetic theories. Overall, the biological properties of these proteins, including their abortifacient, anticancer, antiviral and neurotoxic activities, suggest that RIPs could be utilized in agriculture and in many biomedical fields, including clinical drug development.
Evolution of Plant Ribosome-Inactivating Proteins
Plant Cell Monographs, 2010
This contribution presents an updated analysis of the evolution of ribosome-inactivating proteins (RIPs) in plants. All evidence suggests that an ancestor of modern seed plants developed the RIP domain at least 300 million years ago. This ancestral RIP domain gave rise to a direct lineage of type 1 RIPs (i.e., primary type 1 RIPs) still present today in many monocots and at least one dicot. In a later stage, a plant succeeded in fusing the RIP domain to a duplicated ricin-B domain acquired from a bacterium. The resulting ancestral type 2 RIP gave rise to all modern type 2 RIPs and by domain deletion, to different lines of "secondary" type 1 RIPs and ricin-B type lectins. In the recent past, at least three other domain fusions took place in the Poaceae family, whereby type AC1 (type 3), type AC2, and type AD chimeric forms were generated.
Expressing of rice ribosome inactivating protein as tool for treatment of cancer cells
Scientific Research and Essays, 2012
Ribosome-inactivating proteins (RIPs) are toxic proteins synthesized by many plants and some bacteria, that specifically depurinate the 28S RNA and thus interrupt protein translation. RIPs hold broad interest because of their potential use as plant defense factors against pathogens and cancer cells. The most promising way to exploit plant RIPs as weapons against cancer cells is either by designing molecules in which the toxic domains of RIPs are linked to selective tumor targeting domains or directly delivered as suicide genes for cancer gene therapy. In this research the sequence of rice RIP gene was synthesized in PUC57 plasmid. The gene was cloned in pPICZαA vector and expressed in Pichia pastoris KM71H (mut s) strain. The expected protein which had an apparent molecular mass of 34 kDa was detected by SDS-PAGE analysis and confirmed by Western blot.
The rice tapetum-specific gene RA39 encodes a type I ribosome-inactivating protein
Sexual Plant Reproduction, 2002
A tapetum-specific cDNA encoded by a rice gene, RA39, was isolated by cDNA subtractive hybridization, differential screening and rapid amplification of cDNA ends. RA39 is a single-copy gene in the rice genome. mRNA in situ hybridization indicates that this gene is a tapetum-specific gene, and highly expressed in the tapetal cells at the meiosis and tetrad stages. The RA39 cDNA is 1,013 bp in length with an open reading frame encoding 298 amino acid residues. This cDNA sequence does not show significant homology to any known sequences in GenBank databases, but its deduced amino acid sequence (RA39) has between 19 and 34% sequence identity to ribosome-inactivating proteins (RIPs). Optimal alignment reveals that the five amino acid residues constituting the active site of the ricin A-chain (Tyr 80 , Tyr 123 , Glu 177 , Arg 180 and Trp 211 ), which are invariant among all RIPs published to date, are conserved in RA39. Recombinant RA39 protein expressed in Escherichia coli was purified to homogeneity. The purified protein exhibits the RNA N-glycosidase activity of RIPs. This demonstrates that RIPs occur in the reproductive organs of rice. The possible function of RA39 in anther development is discussed.
Plant Physiology, 2004
Ribosome-inactivating proteins (RIPs) are N-glycosidases that remove a specific adenine from the sarcin/ricin loop of the large rRNA, thus arresting protein synthesis at the translocation step. In the present study, a protein termed tobacco RIP (TRIP) was isolated from tobacco (Nicotiana tabacum) leaves and purified using ion exchange and gel filtration chromatography in combination with yeast ribosome depurination assays. TRIP has a molecular mass of 26 kD as evidenced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and showed strong N-glycosidase activity as manifested by the depurination of yeast rRNA. Purified TRIP showed immunoreactivity with antibodies of RIPs from Mirabilis expansa. TRIP released fewer amounts of adenine residues from ribosomal (Artemia sp. and rat ribosomes) and non-ribosomal substrates (herring sperm DNA, rRNA, and tRNA) compared with other RIPs. TRIP inhibited translation in wheat (Triticum aestivum) germ more efficiently than in rabbit reticu...
Cofactor requirement of ribosome-inactivating proteins from plants
Journal of …, 1997
A large number of type 1 ribosome-inactivating proteins (RIPs) from plants (families of Caryophyllaceae, Cucurbitaceae, Euphorbiaceae, Phytolaccaceae, and Poaceae) were examined for their requirement for ATP and supernatant factors for full activity. A marked requirement was observed with agrostin among Caryophyllaceae, gelonin among Euphorbiaceae, and with both barley RIP and tritin-S among Poaceae. The distribution of cofactor requirement in Phytolaccaceae discriminates leaf forms (cofactor-independent) from seed and root forms (cofactor-dependent). The results are discussed on the basis of the present knowledge on the tissue localization of RIPs and on the sensitivity of ribosomes to conspecific RIPs.
Type 1 ribosome-inactivating proteins from the ombú tree (phytolacca dioica L.)
2010
The toxicity of plant proteins, later identified as ribosome-inactivating proteins (RIPs), was described more than a century ago and their enzymatic activity was established more than 30 years ago. However, their physiological role and related biological activities are still uncertain. Therefore, despite the body of literature, research on RIPs is ongoing. This review deals with new RIPs being purified, sequenced, characterized, and cloned, and an increasing number of 3D-structures that are determined at high resolution. This is the case of the five type 1 RIPs (PD-S1-3, PD-L1/2, PD-L3/4, dioicin 1, and dioicin 2) from seeds and leaves of the ombú tree (Phytolacca dioica L.), native of the grassy pampas of Argentina. The data collected so far will contribute to our understanding of important issues of RIP research: (1) identifying structural determinants responsible for new enzymatic activities such as the DNA cleaving activity; (2) glycosylation and its influence on the catalytic and biological activities; (3) cellular localization of endogenous RIPs and their physiological role(s).