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.
Shimizu-Ibuka
Akiko
A
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.
Nakai
Yuji
Y
Nakamori
Keisuke
K
Morita
Yuji
Y
Nakajima
Ken-Ichiro
K
Kadota
Koji
K
Watanabe
Hirohito
H
Okubo
Satoshi
S
Terada
Tohru
T
Asakura
Tomiko
T
Misaka
Takumi
T
Abe
Keiko
K
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