Pulsed EPR Study of the light-induced redox active in a blue light sensor protein TePixD

Abstract

BLUF domain is a flavin-binding domain that functions as a blue light. The structure of BLUF-domain protein TePixD Thermosynechococcus elongatus BP-1 was reported by Kita et al. [1]. Upon illumination, the absorption band of flavin shows the 10-20 nm red shift. Further illumination induced FAD radical [2]. The illumination of the TePixD at 80-150 K was found to induce a new EPR signal at g=2 region, which was composed of the main two lines separated by 85 gauss, estimated as 6.9 A of the inter-distance. Pulsed ENDOR results suggested that the signal involves the falvosemiquinone and tyrosine neutral radicals. It can be interpreted by the interaction between flavosemiquinone and Y8 neutral radical.
[1] Kita et al., J. Mol. Biol., 2005, 349, 1-9.
[2]Fukushima et al. Biochemistry, 2007, in press