发布: 2017年03月20日第7卷第6期 DOI: 10.21769/BioProtoc.2180 浏览次数: 11621
评审: Zhaohui LiuTzvetina BrumbarovaFeng Li
Abstract
Ribosome-inactivating proteins (RIPs) are enzymes that irreversibly inactivate ribosomes as a consequence of their N-glycosylase (EC 3.2.2.22) activity. The enzyme cleaves the N-glycosidic bond between the adenine No. 4324 from the 28S rRNA and its ribose in rat ribosomes (or the equivalent adenine in sensitive ribosomes from other organisms). This adenine is located in the α-sarcin-ricin loop (SRL) that is crucial for anchoring the elongation factor (EF) G and EF2 on the ribosome during mRNA-tRNA translocation in prokaryotes and eukaryotes, respectively. RIPs have been isolated mainly from plants and examples of these proteins are ricin or Pokeweed Antiviral Protein (PAP). These proteins, either alone or as a part of immunotoxins, are useful tools for cancer therapy. The following protocol describes a method to detect the RNA fragment released when the RIP-treated apurinic RNA from rabbit reticulocyte lysate is incubated in the presence of acid aniline by electrophoresis on polyacrylamide gels. The fragment released (Endo’s fragment) is diagnostic of the action of RIPs.
Keywords: Ribosome-inactivating protein (RIP) (核糖体灭活蛋白(RIP))Background
N-glycosylase activity of RIPs on the eukaryotic 28S rRNA was first described by Endo and Tsurugi for ricin (Endo and Tsurugi, 1988) in rat ribosomes; subsequently it was shown that some RIPs can also depurinate ribosomes from plants, bacteria and fungi. The result of this effect, upon treatment with aniline, is the release of an RNA fragment of between 240 and 500 nucleotides (depending on species) from the rRNA of the large subunit (Figure 1). Most RIPs depurinate ribosomes at one site (the adenine 4,324), whereas other RIPs such as saporins, PAP-R and trichokirin depurinate the rRNA at multiple sites. The protocol described here uses rabbit reticulocyte lysate, a eukaryotic cell-free model system very sensitive to the action of RIPs, which shows high rates of depurination for most RIPs. This allows obtaining a large amount of fragment which facilitates its detection by electrophoresis. In this procedure we use denaturing polyacrylamide minigels which require small quantities of sample and have higher resolution than the agarose gels when staining with fluorescent dyes.
Figure 1. Sarcin Ricin Loop of the large rRNA from rat, yeast and Escherichia coli. The sequences (accession numbers NR_046246, J01355 and AB035926) were downloaded from the NCBI sequence database (http://www.ncbi.nlm.nih.gov/nucleotide/). The adenine released by the RIP action (boldfaced), the site of splitting by either the aniline or α-sarcin (arrows) and the size of the generated fragment are also indicated. Partial sequence of rabbit 28S rRNA (AF460236) indicates that rat and rabbit share the same SRL sequence.
Materials and Reagents
Note: All the reagents used in preparing buffers should be of molecular biology grade purity (RNase, DNase-free). Water and solutions should be autoclaved at 120 °C for 15 min (except of aniline and ethanol).
Equipment
Procedure
文章信息
版权信息
© 2017 The Authors; exclusive licensee Bio-protocol LLC.
如何引用
Iglesias, R., Citores, L. and Ferreras, J. M. (2017). Ribosomal RNA N-glycosylase Activity Assay of Ribosome-inactivating Proteins. Bio-protocol 7(6): e2180. DOI: 10.21769/BioProtoc.2180.
分类
植物科学 > 植物分子生物学 > 蛋白质
植物科学 > 植物生物化学 > 蛋白质
分子生物学 > 蛋白质 > 抗微生物分析
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