KM+, a mannose‐binding lectin from artocarpus integrifolia: Amino acid sequence, predicted tertiary structure, carbohydrate recognition, and analysis of the β‐prism fold

Abstract

The complete amino acid sequence of the lectin KMϩ from Artocarpus integrifolia~jackfruit!, which contains 149 residues0mol, is reported and compared to those of other members of the Moraceae family, particularly that of jacalin, also from jackfruit, with which it shares 52% sequence identity. KMϩ presents an acetyl-blocked N-terminus and is not posttranslationally modified by proteolytic cleavage as is the case for jacalin. Rather, it possesses a short, glycine-rich linker that unites the regions homologous to the a-and b-chains of jacalin. The results of homology modeling implicate the linker sequence in sterically impeding rotation of the side chain of Asp141 within the binding site pocket. As a consequence, the aspartic acid is locked into a conformation adequate only for the recognition of equatorial hydroxyl groups on the C4 epimeric center~a-d-mannose, a-d-glucose, and their derivatives!. In contrast, the internal cleavage of the jacalin chain permits free rotation of the homologous aspartic acid, rendering it capable of accepting hydrogen bonds from both possible hydroxyl configurations on C4. We suggest that, together with direct recognition of epimeric hydroxyls and the steric exclusion of disfavored ligands, conformational restriction of the lectin should be considered to be a new mechanism by which selectivity may be built into carbohydrate binding sites. Jacalin and KMϩ adopt the b-prism fold already observed in two unrelated protein families. Despite presenting little or no sequence similarity, an analysis of the b-prism reveals a canonical feature repeatedly present in all such structures, which is based on six largely hydrophobic residues within a b-hairpin containing two classic-type b-bulges. We suggest the term b-prism motif to describe this feature.

Real-time monitoring and kinetic parameter estimation of the affinity interaction of jArtinM and rArtinM with peroxidase glycoprotein by the electrogravimetric technique

“…ArtinM is a tetrameric non-glycosylated protein composed of identical 16 kDa protomers, each one consisting of a single polypeptide chain of 149 amino acid residues (Rosa et al, 1999). The protein CRDs (1 per protomer and 4 per whole protein) binds to D-mannose, preferentially recognizing N-linked glycans containing the trimannoside core Man␣1-3[Man␣1-6]Man (Jeyaprakash et al, 2004), such as those linked to the horseradish peroxidase (HRP), TLR2 (Coltri et al, 2008), laminin (Ganiko et al, 2005) and CXCR2 glycoproteins (Pereira- .…”

Determinação da Constante de Afinidade da Lectina ArtinM-Célula Leucêmica (NB4) por meio da Técnica Piezoelétrica de Microbalança a Cristal de Quartzo (QCM)

“…Como é possível observar, o valor de K a é maior para a primeira situação e isto pode estar relacionado à diferença na oligomerização da cadeia peptídica. Enquanto em ArtinM nativa os monômeros (13kD) se associam de forma não-covalente e originam tetrâmeros de 54 kD 11 , rArtinM apresenta-se na forma monomérica. Possivelmente, a lectina nativa, por ser tetramérica, tem uma maior possibilidade de interagir com maior número de receptores da NB4 simultaneamente, gerando assim, um valor mais alto de K a .…”

Inhibition of Hepatocarcinogenesis by ArtinM via Anti-proliferative and Pro-apoptotic Mechanisms

“…Lectins are carbohydrate-binding proteins or glycoproteins of non-immune origin that recognize and reversibly bind to glycans without altering their covalent structure. Plant lectins are important tools in cell biology and immunology because they show potential for clinical application (8,9). Lectins can identify glycan determinants that are markers of clinical interest and possess antitumor and anti-carcinogenic properties that could be useful in the development of cancer therapeutics.…”