Ebulitins: A new family of type 1 ribosome‐inactivating proteins (rRNA N‐glycosidases) from leaves of Sambucus ebulus L. that coexist with the type 2 ribosome‐inactivating protein ebulin 1

Abstract

A new family of single chain (type 1) ribosome-inactivating proteins (RIPs), that we have named ebulitins, have been found in mature leaves of Sambucus ebulus L., a caprifoliaceae plant also known to contain a non-toxic two chain (type 2) RIP named ebulin 1 in its leaves. Ebulitins are basic proteins of Mr 32,000, 29,000 and 29,000 for ebulitins a,/3 and T, respectively. The simultaneous presence of different basic type 1 and acidic type 2 RIPs in the same plant and in the same tissue is described here for the first time and opens a new door in research into RIPs.

Elderberries: A Source of Ribosome-Inactivating Proteins with Lectin Activity

“…Ebulitins are basic proteins that belong to single-chain (type 1) RIPs and have been isolated from leaves of S. ebulus L. by cation-exchange chromatography, gel filtration and Blue-Sepharose affinity chromatography [ 27 ]. Three ebulitins named α, β, and γ have been isolated to date.…”

“…In contrast, they do not inhibit translation in plant cell-free systems. The three ebulitins display N -glycosidase activity on 28S rRNA rabbit reticulocyte lysates [ 27 ].…”

“…In rat-liver cell-free systems, they show IC 50 values of 15 nM for nigritin f1 and 268 nM for nigritin f2. As occurs with ebulitins, they do not inhibit translation in plant cell-free systems and display N -glycosidase activity on 28S rRNA rabbit reticulocyte lysates [ 27 ]. Additionally, they display topological activity, turning supercoiled circular DNA into linear and relaxed circular DNA forms [ 28 ].…”

Use of Ribosome-Inactivating Proteins from Sambucus for the Construction of Immunotoxins and Conjugates for Cancer Therapy

“…They have been found in S. ebulus leaves (ebulitins α, β, and γ) [33] and S. nigra fruits (nigritins f1 and f2) [34]. …”

“…These monomeric lectins could be encoded by a truncated type 2 RIP gene which has lost a substantial part, if not all, coding for the A chain and therefore lost its enzymic activity. To date, there is no sequence data available on type 1 RIPs from Sambucus because the N -terminals of the proteins studied are blocked [33]. …”