Molecular modelling of miraculin: Structural analyses and functional hypotheses.
Miraculin is a plant protein that displays the peculiar property of modifying taste by swiching sour into a sweet taste. Its monomer is flavourless at all pH as well as at high concentration; the dimer form elicits its taste-modifying activity at acidic pH; a tetrameric form is also reported as active. Two histidine residues, located in exposed regions, are the main responsible of miraculin activity, as demonstrated by mutagenesis studies. Since structural data of miraculin are not available, we have predicted its three-dimensional structure and simulated both its dimer and tetramer forms by comparative modelling and molecular docking techniques. Finally, molecular dynamics simulations at different pH conditions have indicated that at acidic pH the dimer assumes a widely open conformation, in agreement with the hypotheses coming from other studies.
Paladino
Antonella
A
Laboratory of Bioinformatics and Computational Biology, National Council of Researches, Institute of Food Sciences ISA - CNR, via Roma 52A/C, 83100 Avellino, Italy.
Costantini
Susan
S
Colonna
Giovanni
G
Facchiano
Angelo M
AM
D000465:Algorithms; D003198:Computer Simulation; D019281:Dimerization; D006023:Glycoproteins / Q000032:analysis / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D010940:Plant Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D013549:Sweetening Agents / Q000032:analysis / Q000737:chemistry*
D006023:Glycoproteins; D010940:Plant Proteins; D013549:Sweetening Agents; C008533:miraculin protein, Synsepalum dulcificum; D006639:Histidine