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Unique tuning of two cofactors in a cryptochrome framework
Author(s) -
Hitomi Kenichi,
Arvai Andrew S,
Getzoff Elizabeth D
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.lb228
Subject(s) - cryptochrome , photolyase , cofactor , flavin group , flavin adenine dinucleotide , flavin mononucleotide , biology , biochemistry , gene , dna repair , enzyme , circadian clock
We have determined the 1.75 Åresolution crystallographic structure of Synechocystis cryptochrome with both cofactors bound. This protein product from the Sll1629 gene of Synechocystis sp. PCC6803 belongs to the blue light photoreceptor cryptochrome/ photolyase family and binds both flavin adenine dinucleotide (FAD) and N5,N10‐methenyl‐5,6,7,8 tetrahydrofolate (MTHF). For many eukaryotic proteins of the cryptochrome/photolyase family, MTHF has been implicated by spectroscopic studies as a second "antenna" cofactor, in addition to the redox‐active FAD cofactor. In contrast, recent structural studies of prokaryotic proteins from this family have indicated alternative options for the second cofactor: 8‐hydroxy‐5‐deazaflavin, flavin mononucleotide (FMN) or another FAD. The cofactor‐binding sites in our Synechocystis protein structure are not only perfectly matched with those of plant homolog, but also well conserved among the cryptochrome DASH gene cluster, which has bacterial, plant and animal members. The binding of MTHF in our Synechocystis protein structure is more constrained by protein interactions than is MTHF binding in E. coli photolyase. Structural and mutational analyses indicate that both cofactors are regulated differently in the DASH cluster proteins than in the bacterial photolyase.