TY - JOUR
T1 - Photo-induced peptide cleavage in the green-to-red conversion of a fluorescent protein
AU - Mizuno, Hideaki
AU - Mal, Tapas Kumar
AU - Tong, Kit I.
AU - Ando, Ryoko
AU - Furuta, Toshiaki
AU - Ikura, Mitsuhiko
AU - Miyawaki, Atsushi
N1 - Funding Information:
We thank Dr. M. Usui, Dr. K. Otsuki, Dr. N. Hirotani, Dr. T. Suenaga, and Dr. M. Ito for assistance and encouragement. We also acknowledge Dr. Roger Y. Tsien for valuable advice, and Dr. Markus Waelchli (Bruker-Biospin Japan) for help in recording NMR. This work was supported by grants from CREST of JST (Japan Science and Technology), the Japanese Ministry of Education, Science and Technology, and HFSP (Human Frontier Science Program) to A.M. and by a grant from Cancer Research Society Inc/Canadian Institute of Health Research to M.I.
PY - 2003/10
Y1 - 2003/10
N2 - Green fluorescent protein from the jellyfish (Aequorea GFP) and GFP-like proteins from coral species encode light-absorbing chromophores within their protein sequences. A coral fluorescent protein, Kaede, contains a tripeptide, His62-Tyr63-Gly64, which acts as a green chromophore that is photoconverted to red. Here, we present the structural basis for the green-to-red photoconversion. As in Aequorea GFP, a chromophore, 4-(p-hydroxybenzylidene)-5-imidazolinone, derived from the tripeptide mediates green fluorescence in Kaede. UV irradiation causes an unconventional cleavage within Kaede protein between the amide nitrogen and the α carbon (Cα) at His62 via a formal β-elimination reaction, which requires the whole, intact protein for its catalysis. The subsequent formation of a double bond between His62-Cα and -Cβ extends the π-conjugation to the imidazole ring of His62, creating a new red-emitting chromophore, 2-[(1E)-2-(5-imidazolyl)ethenyl]-4-(p- hydroxybenzylidene)-5-imidazolinone. The present study not only reveals diversity in the chemical structure of fluorescent proteins but also adds a new dimension to posttranslational modification mechanisms.
AB - Green fluorescent protein from the jellyfish (Aequorea GFP) and GFP-like proteins from coral species encode light-absorbing chromophores within their protein sequences. A coral fluorescent protein, Kaede, contains a tripeptide, His62-Tyr63-Gly64, which acts as a green chromophore that is photoconverted to red. Here, we present the structural basis for the green-to-red photoconversion. As in Aequorea GFP, a chromophore, 4-(p-hydroxybenzylidene)-5-imidazolinone, derived from the tripeptide mediates green fluorescence in Kaede. UV irradiation causes an unconventional cleavage within Kaede protein between the amide nitrogen and the α carbon (Cα) at His62 via a formal β-elimination reaction, which requires the whole, intact protein for its catalysis. The subsequent formation of a double bond between His62-Cα and -Cβ extends the π-conjugation to the imidazole ring of His62, creating a new red-emitting chromophore, 2-[(1E)-2-(5-imidazolyl)ethenyl]-4-(p- hydroxybenzylidene)-5-imidazolinone. The present study not only reveals diversity in the chemical structure of fluorescent proteins but also adds a new dimension to posttranslational modification mechanisms.
UR - http://www.scopus.com/inward/record.url?scp=0242361312&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0242361312&partnerID=8YFLogxK
U2 - 10.1016/S1097-2765(03)00393-9
DO - 10.1016/S1097-2765(03)00393-9
M3 - Article
C2 - 14580354
AN - SCOPUS:0242361312
SN - 1097-2765
VL - 12
SP - 1051
EP - 1058
JO - Molecular cell
JF - Molecular cell
IS - 4
ER -