Ricin A chain (RA), an N-glycosidase, is able to fatally disrupt protein synthesis by attacking the Achilles heel of the ribosome RNA (rRNA). As specific immunotoxins, emergence of inhibitors for RA may obtain access to antagonistics against ricin intoxication and contribute to ameliorate the concomitant side effects. Many experimental results showed that the engineered VHs, which possessed solubility, stability, small size and consequently easier to express, purify and manipulate in vitro, were self and long-lived molecules compared to synthetic peptides. In this study, based on the crystal structure of RA, a novel recombinant human single-domain antibody expressing a polypeptide against RA in the CDR3 loop (named rVH(PT)) was obtained using computer-guided molecular design method. Theoretically, rVH(PT) could penetrate deeply into the active cleft of RA and act as a potent antagonist analogue to block the RA-rRNA interaction. Followed results showed that the recombinant VH(PT) was easily expressed of high-yield production and in a partially soluble fusion form in Escherichia coli. In vitro cytotoxicity experiments demonstrated that it possessed remarkable ability to block ricin-induced cytotoxicity. This study highlights the potential of human VH to display biostructure and biofunction of peptides designed on RA functional domain and could be useful in developing new antidotes with potential therapeutic uses to neutralize unintended exposure to ricin.
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http://dx.doi.org/10.1016/j.molimm.2005.10.012 | DOI Listing |
J Biomol Struct Dyn
October 2024
Biomolecular Structure and Dynamics Group, Department of Biotechnology, National Institute of Technology, Warangal, India.
Ribosome Inactivating Proteins (RIPs) act by irreversibly depurinating the 28S rRNA ricin-sarcin loop (SRL) of the eukaryotic ribosome resulting in protein synthesis inhibition. In general, they consist of two variants: Type I which is single chained (∼30 kDa), and Type II, a more toxic variant which is a Type I N-glycosidase chain covalently linked to a lectin chain. These proteins are believed to play a pivotal role in defence mechanisms.
View Article and Find Full Text PDFToxins (Basel)
October 2024
The Manchester Institute of Biotechnology, Faculty of Biology, Medicine & Health, University of Manchester, Manchester M13 9PL, UK.
Malanin is a new type II ribosome-inactivating protein (RIP) purified from , a rare, endangered tree is only found in the southwest of Guangxi Province and the southeast of Yunnan Province, China. The gene coding sequence of malanin was found from the cDNA library of seeds by employing the ten N-terminal amino acid sequences of malanin, DYPKLTFTTS for chain-A and DETXTDEEFN (X was commonly C) for chain-B. The results showed a 65% amino acid sequence homology between malanin and ricin by DNAMAN 9.
View Article and Find Full Text PDFAnal Methods
November 2024
National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
A simple, accurate method for measuring ricin activity was developed by detecting depurinated nucleic acid stem-loops and adenine using a commercially available hydrophilic interaction liquid chromatography (HILIC) column and a quadrupole-Orbitrap tandem mass spectrometer. Ricin in beverages was isolated using magnetic beads conjugated with ricin B-chain antibodies, and then incubated with a 14 mer RNA or a 12 mer RNA/DNA chimera, in which adenosine at the depurination site of RNA was replaced by deoxyadenosine. The adenine and depurinated nucleic acids were separated by HILIC and both analytes were detected by high-resolution mass spectrometry.
View Article and Find Full Text PDFJ Virol
October 2024
Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA.
HIV-infected cells persisting in the face of suppressive antiretroviral therapy are the barrier to curing infection. Cytotoxic immunoconjugates targeted to HIV antigens on the cell surface may clear these cells. We showed efficacy in mouse and macaque models using immunotoxins, but immunogenicity blunted the effect.
View Article and Find Full Text PDFJ Immunol Methods
October 2024
Department of Biology, Yadegar-e-Imam Khomeini (RAH) Shahr-e-Rey Branch, Islamic Azad University, Tehran, Iran.
Breast cancer is one of the leading causes of cancer deaths worldwide. Thereafter, designing new treatments with higher specificity and efficacy is urgently required. In this regard, targeted immunotherapy using immunotoxins has shown great promise in treating cancer.
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