Plumieribetin, a Fish Lectin Homologous to Mannose-binding B-type Lectins, Inhibits the Collagen-binding α1β1 Integrin

Abstract

Recently, a few fish proteins have been described with a high homology to B-type lectins of monocotyledonous plants. Because of their mannose binding activity, they have been ascribed a role in innate immunity. By screening various fish venoms for their integrin inhibitory activity, we isolated a homologous protein from the fin stings and skin mucus of the scorpionfish (Scorpaena plumieri). This protein inhibits ␣1␤1 integrin binding to basement membrane collagen IV. By protein chemical and spectroscopic means, we demonstrated that this fish protein, called plumieribetin, is a homotetramer and contains a high content of anti-parallel ␤ strands, similar to the mannose-binding monocot B-lectins. It lacks both N-linked glycoconjugates and common O-glycan motifs. Despite its B-lectin-like structure, plumieribetin binds to ␣1␤1 integrin irrespective of N-glycosylation, suggesting a direct protein-protein interaction. This interaction is independent of divalent cations. On the cellular level, plumieribetin failed to completely detach hepatocarcinoma HepG2 cells and primary arterial smooth muscle cells from the collagen IV fragment CB3. However, plumieribetin weakened the cell-collagen contacts, reduced cell spreading, and altered the actin cytoskeleton, after the compensating ␣2␤1 integrin was blocked. The integrin inhibiting effect of plumieribetin adds a new function to the B-lectin family, which is known for pathogen defense.

Expressed sequence tags in venomous tissue of Scorpaena plumieri (Scorpaeniformes: Scorpaenidae)

“…The inhibition contributes to the local and systemic effect of envenomation by scorpionfish (De Santana Evangelista, 2009). Plumieribetin is a homotetrameric protein displaying high content of antiparallel B-strands, similar to the mannosebinding monocotiledons-B-lectins.…”

“…However, local envenomation effects are also attributed to the presence of the β-lectin plumieribetin isolated from S. plumieri (De Santana Evangelista, 2009). The fully characterized protein (14.4 kDa) acts as α1β1 integrin inhibitor similar to monocot mannose-binding B-lectins and to pufflectin found in skin and intestine of Japanese pufferfish/Fugu fish (Takifugu rubripes) (Tsutsui et al, 2003).…”

Nattectin a fish C-type lectin drives Th1 responses in vivo: Licenses macrophages to differentiate into cells exhibiting typical DC function

“…Fish lectins have been extensively described within tissues and cells associated with host defensive functions (branchial epithelium, renal interstitium, hepatic sinusoidal, intestinal sub-mucosal granular layer, skin and particularly within circulating granulocytes), however only recently, a tetrameric lectin belonging to the family of mannosebinding B-type was isolated from the mucus and sting of Scorpaena plumieri venomous fish [15].…”

The binding capacity of α1β1-, α2β1- and α10β1-integrins depends on non-collagenous surface macromolecules rather than the collagens in cartilage fibrils

“…Soluble recombinant human integrins α1β1 and α2β1, in which the transmembrane-and intracellular domains were replaced by a jun-/fos-zipper motif, were prepared as described [53,54]. The cDNA encoding α10 integrin chain [55] within the plasmid pcDNA3 α10 was digested with Acc65I-and AvrII and a fragment of 2900 bp encoding the N-terminal portion of the α10 integrin ectodomain was isolated.…”

“…This cDNA was cloned into the pUC-HMT-α1fos construct by replacing the integrin α1 ectodomain-encoding sequence via the AgeI site as well as the blunted AvrII and SalI sites of the insert and vector, respectively. The plasmid was transfected into Drosophila S2 Schneider cells together with the pUC-HMT-β1jun-construct, and the ectodomain of integrin α10β1 was isolated and purified as described [53,54].…”