Biochemical and genomic analysis of neoculin compared to monocot mannose-binding lectins.
Neoculin occurring in an edible tropical fruit is a heterodimeric protein which has both sweetness and a taste-modifying activity that converts sourness to sweetness. Both the primary and the overall tertiary structures of neoculin resemble those of monocot mannose-binding lectins. This study investigated differences in biochemical properties between neoculin and the lectins. Structural comparison between the mannose-binding sites of lectins and the corresponding regions of neoculin showed that there is at least one amino acid substitution at each site in neoculin, suggesting a reason for the lack of its mannose-binding ability. This was consistent with hemagglutination assay data demonstrating that neoculin had no detectable agglutinin activity. DNA microarray analysis indicated that neoculin had no significant influence on gene expression in Caco-2 cell, whereas kidney bean lectin (Phaseolus vulgaris agglutinin) greatly influenced various gene expressions. These data strongly suggest that neoculin has no lectin-like properties, encouraging its practical use in the food industry.
Department of Applied Biological Chemistry and Agricultural Bioinformatics Research Unit, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Akiko
A
Shimizu-Ibuka
Yuji
Y
Nakai
Keisuke
K
Nakamori
Yuji
Y
Morita
Ken-Ichiro
K
Nakajima
Koji
K
Kadota
Hirohito
H
Watanabe
Satoshi
S
Okubo
Tohru
T
Terada
Tomiko
T
Asakura
Takumi
T
Misaka
Keiko
K
Abe
D000595:Amino Acid Sequence; D018938:Caco-2 Cells; D002470:Cell Survival / Q000187:drug effects; D018360:Crystallography, X-Ray; D015870:Gene Expression / Q000187:drug effects; D023281:Genomics; D006384:Hemagglutination; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000502:physiology; D037241:Mannose-Binding Lectins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D010944:Plants / Q000145:classification / Q000235:genetics; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
D037241:Mannose-Binding Lectins; D010940:Plant Proteins; C511659:neoculin protein, Curculigo latifolia