Neoculin as a New Taste-modifying Protein Occurring in the Fruit of<i>Curculigo latifolia</i>

Shirasuka, Yukako; Nakajima, Ken-ichiro; Asakura, Tomiko; Yamashita, Haruo; Yamamoto, Atsuko; Hata, Shoji; Nagata, Shinji; Abo, Mitsuru; Sorimachi, Hiroyuki; Abe, Keiko

doi:10.1271/bbb.68.1403

Cited by 68 publications

(57 citation statements)

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“…MCL and NCL were isolated from the fruits of R. dulcifica and Curculigo latifolia, respectively, and purified as described previously (7,11). Recombinant brazzein has been expressed using the yeast Pichia pastoris.…”

Section: Methodsmentioning

confidence: 99%

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Human sweet taste receptor mediates acid-induced sweetness of miraculin

Koizumi¹,

Tsuchiya²,

Nakajima³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Miraculin (MCL) is a homodimeric protein isolated from the red berries of Richadella dulcifica. MCL, although flat in taste at neutral pH, has taste-modifying activity to convert sour stimuli to sweetness. Once MCL is held on the tongue, strong sweetness is sensed over 1 h each time we taste a sour solution. Nevertheless, no molecular mechanism underlying the taste-modifying activity has been clarified. In this study, we succeeded in quantitatively evaluating the acid-induced sweetness of MCL using a cell-based assay system and found that MCL activated hT1R2-hT1R3 pHdependently as the pH decreased from 6.5 to 4.8, and that the receptor activation occurred every time an acid solution was applied. Although MCL per se is sensory-inactive at pH 6.7 or higher, it suppressed the response of hT1R2-hT1R3 to other sweeteners at neutral pH and enhanced the response at weakly acidic pH. Using human/mouse chimeric receptors and molecular modeling, we revealed that the amino-terminal domain of hT1R2 is required for the response to MCL. Our data suggest that MCL binds hT1R2-hT1R3 as an antagonist at neutral pH and functionally changes into an agonist at acidic pH, and we conclude this may cause its taste-modifying activity.G protein-coupled receptor | positive allosteric modulator | taste-modifying protein | calcium imaging

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Section: Methodsmentioning

confidence: 99%

“…Unlike MCL, NCL per se tastes sweet, but tastes much sweeter at acidic pH (7,8). We have recently revealed that NCL is functionally in pH-dependent equilibrium between the active and inactive forms because it activates hT1R2-hT1R3 at acidic pH but inhibits the activation of the receptor at neutral pH (9,10).…”

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confidence: 99%

Human sweet taste receptor mediates acid-induced sweetness of miraculin

Koizumi¹,

Tsuchiya²,

Nakajima³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…The fruit of Curculigo latifolia produces a protein named neoculin (Shirasuka et al, 2004;Yamashita et al, 1990). Neoculin is approximately 500 times sweeter than sucrose by weight and has unique activity to convert a sour to a sweet taste.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Pistil Size and Self-incompatibility on Fruit Production in Curculigo latifolia (Liliaceae)

Okubo

Yamada

Yamaura

et al. 2010

J. Japan. Soc. Hort. Sci.

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The shapes of flowers and the cross-compatibility of Curculigo latifolia, which produces a taste-modifying protein, neoculin, were investigated for the purpose of setting fruits in Japan as a resource of neoculin. C. latifolia is an andromonoecious plant, that is, flowers in a lower position in an inflorescence are hermaphrodite with long styles, although flowers in higher positions are staminate with short styles. This shows that 22% of all flowers were hermaphroditic in an inflorescence. By the hand-pollination study, the largest rate of setting C. latifolia fruits was shown by the 5th day from the first flowering. The rates of fruit set were gradually reduced after that day. The number of fruits peaked by the 13th day from first flowering. On the other hand, the rate of fruit setting was shown to be 45% by cross-pollination and 4% by self-pollination. These results indicate that C. latifolia has selfincompatibility. To improve the rate of fruit setting of C. latifolia, it is necessary to pollinate compatible pollen by around the 15th day after the first flowering.

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“…9,11) This indicates that not only acidic substances but others can induce the intense sweet taste of neoculin. This is the first report on compounds with this activity.…”

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confidence: 98%

“…9,10) Neoculin can be isolated from the edible fruit of Curculigo latifolia, found in West Malaysia. It has a weak sweet taste of its own and elicits strong sweetness shortly after tasting an acidic solution.…”

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confidence: 99%