Taste-Modifying Protein from Miracle Fruit

Kurihara, Kenzo; Beidler, Lloyd M.

doi:10.1126/science.161.3847.1241

Cited by 174 publications

(91 citation statements)

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“…Miraculin is a taste-modifying protein made by miracle fruit (Richadella dulcifica) (Theerasilp and Kurihara 1988) that causes sour tastes to be perceived as sweet (Brouwer et al 1968;Kurihara and Beidler 1968). Individuals suffering from diseases such as obesity, diabetes, hyperglycemia and caries could use miraculin as a natural low-calorie sweetener (Kant 2005).…”

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Gene dosage and genetic background affect miraculin accumulation in transgenic tomato fruits

Kim

Hirai

Kato

et al. 2010

Plant Biotechnology

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Gene dosage and genetic background are factors that influence transgene expression in transgenic plants. In our previous studies, we produced transgenic tomato plants that accumulate miraculin, a taste-modifying protein, in a genetically stable manner. To elucidate the effects of gene dosage and genetic background on miraculin accumulation in transgenic tomato fruits, we generated hybrid tomato lines between the homozygous transgenic line 56B (background cultivar 'Moneymaker') and the pure cultivars 'Micro-Tom,' 'Moneymaker,' 'Ailsa Craig,' 'M82,' 'Rutgers' and 'Aichi-first' and analyzed them for miraculin mRNA expression and miraculin protein accumulation. The hybrid lines exhibited variation in their fruit structures. Among the hybrid lines heterozygous for the miraculin gene, miraculin accumulation in the fruits varied from 111.0 mg g Ϫ1 fresh weight (FW) to 159.4 mg g Ϫ1 FW. Furthermore, the homozygous line 56B showed higher miraculin accumulation and miraculin mRNA expression than the heterozygous line 56Bϫ'Moneymaker.' These results demonstrate the profound effects of gene dosage and genetic background on miraculin accumulation in transgenic tomato fruits.Key words: Gene dosage, genetic background, miraculin, taste-modifying protein.Plant Biotechnology 27, 333-338 (2010) Original PaperThis article can be found at http://www.jspcmb.jp/ allelic composition and genetic background affect transgene expression and inheritance in white clover. Another study in rice showed that the expression pattern of Xa3/Xa26, which is a rice disease resistance gene, was affected by the genetic background (Cao et al. 2007). The full effects of gene dosage and genetic background on transgene expression and translation remain to be elucidated.In this study, we generated hybrid lines between transgenic line 56B (background cultivar 'Moneymaker'), which is homozygous for the miraculin gene, and the pure line cultivars 'Micro-Tom,' 'Moneymaker,' 'Ailsa Craig,' 'M82,' 'Rutgers' and 'Aichi-first.' Characterization of the hybrids' miraculin mRNA expression and miraculin protein accumulation, revealed the effects of gene dosage and genetic background on miraculin accumulation in transgenic tomato fruits, and in addition we discuss the significance of combining molecular breeding with cross-breeding to produce transgenic tomatoes that accumulate miraculin. Materials and methods Plant material and growth conditionsThe transgenic tomato line 56B was produced in our previous work (Sun et al. 2007). In brief miraculin encoding 660-bp DNA fragment was inserted into the XbaI/SacI sites of the plant transformation vectors pBI121 (Sun et al. 2006). Line 56B possesses a single copy of the miraculin gene driven by the CaMV 35S promoter.In the present study, the miraculin-accumulating transgenic tomato line 56B (background cultivars 'Moneymaker') was crossed with six other cultivars: 'Micro-Tom (accession number TOMJPF00001), ' 'Moneymaker (accession number TOMJPF00002), ' 'Aichi-first (accession number TOMJPF00003), ' 'Ailsa Cra...

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Gene dosage and genetic background affect miraculin accumulation in transgenic tomato fruits

Kim

Hirai

Kato

et al. 2010

Plant Biotechnology

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“…Miraculin (MCL), a protein found in the fruit of a West-African plant, Richadella dulcifica, is famous for its unique sweet sensation (1,2), which is a homodimeric glycosylated protein composed of 191 amino acid residues (3). Although flat in taste at neutral pH, MCL has taste-modifying activity to convert sour stimuli to sweetness.…”

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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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“…The active principle has recently been purified and characterized by Henning, Brouwer, van der Wei, and Francke (in press), Kurihara and Beidler (1968), and Kurihara, Kurihara, and Beidler (in press). The former group has termed the principle, "miraculin," and the latter groups, "taste modifying protein.…”

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