Study on the interaction between methyl jasmonate and the coiled-coil domain of rice blast resistance protein Pi36 by spectroscopic methods

Interaction between the coiled-coil domain of rice blast resistance protein Pi36 and methyl-jasmonate (MeJA) was studied by fluorescence and UV–vis spectroscopic techniques. The quenching mechanism of fluorescence of MeJA by this domain was discussed to be a static quenching procedure. Fluorescence quenching was explored to measure the number of binding sites n and apparent binding constants K. The thermodynamics parameters ΔH, ΔG, ΔS were also calculated. The results indicate the binding reaction was not entropy-driven but enthalpy-driven, and hydrophobic binding played major role in the interaction. The binding sites of MeJA with the coiled-coil structural domain of rice blast resistance protein Pi36 were found to approach the microenvironment of both Tyr and Trp by the synchronous fluorescence spectrometry. The distance r between donor (the coiled-coil domain of rice blast resistance protein Pi36) and acceptor (MeJA) was obtained according to Förster theory of non-radioactive energy transfer.

At the excitation wavelength of 280 nm, two fluorescence emission peaks of protein appeared at 208 nm and 304 nm. The fluorescence intensity of protein increased with the increasing of MeJA concentration at 208 nm, and a gradually decreased peak of fluorescence emission appeared at 304 nm. These results indicated that the coiled-coil domain interacted with methyl jasmonate, and the interaction resulted in fluorescence quenching of protein.Figure optionsDownload as PowerPoint slideHighlights
► The interaction between methyl jasmonate and the protein CC domain of Rice blast resistance gene Pi36 was studied.
► The conjugates constant K and the number of binding sites n were calculated.
► The distance of the donor–acceptor between methyl jasmonate and the coiled-coil domain of the blast resistance protein Pi36 was obtained.
► The result of binding site of methyl jasmonate with the coiled-coil domain of the resistance protein Pi36 was close to both tyrosine and tryptophan residues was concluded.