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A Spectroscopic Study on Secondary Structure and Thermal Unfolding of the Plant Toxin Gelonin Confirms Some Typical Structural Characteristics and Unravels the Sequence of Thermal Unfolding Events.
Toxins (Basel) 2019; 11(9)T

Abstract

Gelonin from the Indian plant Gelonium multiflorum belongs to the type I ribosome-inactivating proteins (RIPs). Like other members of RIPs, this toxin glycoprotein inhibits protein synthesis of eukaryotic cells; hence, it is largely used in the construction of immunotoxins composed of cell-targeted antibodies. Lysosomal degradation is one of the main issues in targeted tumor therapies, especially for type I RIP-based toxins, as they lack the translocation domains. The result is an attenuated cytosolic delivery and a decrease of the antitumor efficacy of these plant-derived toxins; therefore, strategies to permit their release from endosomal vesicles or modifications of the toxins to make them resistant to degradation are necessary to improve their efficacy. Using infrared spectroscopy, we thoroughly analyzed both the secondary structure and the thermal unfolding of gelonin. Moreover, by the combination of two-dimensional correlation spectroscopy and phase diagram method, it was possible to deduce the sequence of events during the unfolding, confirming the typical characteristic of the RIP members to denature in two steps, as a sequential loss of tertiary and secondary structure was detected at 58 °C and at 65 °C, respectively. Additionally, some discrepancies in the unfolding process between gelonin and saporin-S6, another type I RIP protein, were detected.

Authors+Show Affiliations

Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, 60131 Ancona, Italy.Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, 60131 Ancona, Italy.Departamento de Bioquímica y Biología Molecular "A", Facultad de Veterinaria, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, 30100 Murcia, Spain. aausili@um.es.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31443430

Citation

Scirè, Andrea, et al. "A Spectroscopic Study On Secondary Structure and Thermal Unfolding of the Plant Toxin Gelonin Confirms some Typical Structural Characteristics and Unravels the Sequence of Thermal Unfolding Events." Toxins, vol. 11, no. 9, 2019.
Scirè A, Tanfani F, Ausili A. A Spectroscopic Study on Secondary Structure and Thermal Unfolding of the Plant Toxin Gelonin Confirms Some Typical Structural Characteristics and Unravels the Sequence of Thermal Unfolding Events. Toxins (Basel). 2019;11(9).
Scirè, A., Tanfani, F., & Ausili, A. (2019). A Spectroscopic Study on Secondary Structure and Thermal Unfolding of the Plant Toxin Gelonin Confirms Some Typical Structural Characteristics and Unravels the Sequence of Thermal Unfolding Events. Toxins, 11(9), doi:10.3390/toxins11090483.
Scirè A, Tanfani F, Ausili A. A Spectroscopic Study On Secondary Structure and Thermal Unfolding of the Plant Toxin Gelonin Confirms some Typical Structural Characteristics and Unravels the Sequence of Thermal Unfolding Events. Toxins (Basel). 2019 Aug 22;11(9) PubMed PMID: 31443430.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A Spectroscopic Study on Secondary Structure and Thermal Unfolding of the Plant Toxin Gelonin Confirms Some Typical Structural Characteristics and Unravels the Sequence of Thermal Unfolding Events. AU - Scirè,Andrea, AU - Tanfani,Fabio, AU - Ausili,Alessio, Y1 - 2019/08/22/ PY - 2019/07/30/received PY - 2019/08/19/revised PY - 2019/08/21/accepted PY - 2019/8/25/entrez KW - Gelonin KW - Immunotoxins KW - Infrared spectroscopy KW - Ribosome-inactivating protein KW - Thermal unfolding KW - Two-dimensional correlation spectroscopy JF - Toxins JO - Toxins (Basel) VL - 11 IS - 9 N2 - Gelonin from the Indian plant Gelonium multiflorum belongs to the type I ribosome-inactivating proteins (RIPs). Like other members of RIPs, this toxin glycoprotein inhibits protein synthesis of eukaryotic cells; hence, it is largely used in the construction of immunotoxins composed of cell-targeted antibodies. Lysosomal degradation is one of the main issues in targeted tumor therapies, especially for type I RIP-based toxins, as they lack the translocation domains. The result is an attenuated cytosolic delivery and a decrease of the antitumor efficacy of these plant-derived toxins; therefore, strategies to permit their release from endosomal vesicles or modifications of the toxins to make them resistant to degradation are necessary to improve their efficacy. Using infrared spectroscopy, we thoroughly analyzed both the secondary structure and the thermal unfolding of gelonin. Moreover, by the combination of two-dimensional correlation spectroscopy and phase diagram method, it was possible to deduce the sequence of events during the unfolding, confirming the typical characteristic of the RIP members to denature in two steps, as a sequential loss of tertiary and secondary structure was detected at 58 °C and at 65 °C, respectively. Additionally, some discrepancies in the unfolding process between gelonin and saporin-S6, another type I RIP protein, were detected. SN - 2072-6651 UR - https://www.unboundmedicine.com/medline/citation/31443430/A_Spectroscopic_Study_on_Secondary_Structure_and_Thermal_Unfolding_of_the_Plant_Toxin_Gelonin_Confirms_Some_Typical_Structural_Characteristics_and_Unravels_the_Sequence_of_Thermal_Unfolding_Events L2 - http://www.mdpi.com/resolver?pii=toxins11090483 DB - PRIME DP - Unbound Medicine ER -