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From Proteopedia
INTERACTION OF A LEGUME LECTIN WITH THE N2 FRAGMENT OF HUMAN LACTOTRANSFERRIN OR WITH THE ISOLATED BIANTENNARY GLYCOPEPTIDE: ROLE OF THE FUCOSE MOIETY
Structural highlights
Function[TRFL_HUMAN] Transferrins are iron binding transport proteins which can bind two Fe(3+) ions in association with the binding of an anion, usually bicarbonate.[1] [2] Lactotransferrin has antimicrobial activity which depends on the extracellular cation concentration.[3] [4] Lactoferroxins A, B and C have opioid antagonist activity. Lactoferroxin A shows preference for mu-receptors, while lactoferroxin B and C have somewhat higher degrees of preference for kappa-receptors than for mu-receptors.[5] [6] The lactotransferrin transferrin-like domain 1 functions as a serine protease of the peptidase S60 family that cuts arginine rich regions. This function contributes to the antimicrobial activity.[7] [8] Isoform DeltaLf: transcription factor with antiproliferative properties and inducing cell cycle arrest. Binds to DeltaLf response element found in the SKP1, BAX, DCPS, and SELH promoters.[9] [10] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: Lectins mediate cell-cell interactions by specifically recognizing oligosaccharide chains. Legume lectins serve as mediators for the symbiotic interactions between plants and nitrogen-fixing microorganisms, an important process in the nitrogen cycle. Lectins from the Viciae tribe have a high affinity for the fucosylated biantennary N-acetyllactosamine-type glycans which are to be found in the majority of N-glycosylproteins. While the structures of several lectins complexed with incomplete oligosaccharides have been solved, no previous structure has included the complete glycoprotein. RESULTS: We have determined the crystal structures of Lathyrus ochrus isolectin II complexed with the N2 monoglycosylated fragment of human lactotransferrin (18 kDa) and an isolated glycopeptide (2.1 kDa) fragment of human lactotransferrin (at 3.3 A and 2.8 A resolution, respectively). Comparison between the two structures showed that the protein part of the glycoprotein has little influence on either the stabilization of the complex or the sugar conformation. In both cases the oligosaccharide adopts the same extended conformation. Besides the essential mannose moiety of the monosaccharide-binding site, the fucose-1' of the core has a large surface of interaction with the lectin. This oligosaccharide conformation differs substantially from that seen in the previously determined isolectin I-octasaccharide complex. Comparison of our structure with that of concanavalin A (ConA) suggests that the ConA binding site cannot accommodate this fucose. CONCLUSIONS: Our results explain the observation that Viciae lectins have a higher affinity for fucosylated oligosaccharides than for unfucosylated ones, whereas the affinity of ConA for these types of oligosaccharides is similar. This explanation is testable by mutagenesis experiments. Our structure shows a large complementary surface area between the oligosaccharide and the lectin, in contrast with the recently determined structure of a complex between the carbohydrate recognition domain of a C-type mammalian lectin and an oligomannoside, where only the non-reducing terminal mannose residue interacts with the lectin. Structures of a legume lectin complexed with the human lactotransferrin N2 fragment, and with an isolated biantennary glycopeptide: role of the fucose moiety.,Bourne Y, Mazurier J, Legrand D, Rouge P, Montreuil J, Spik G, Cambillau C Structure. 1994 Mar 15;2(3):209-19. PMID:8069634[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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