Abstract
BLUF is the FAD binding blue-light sensory domain that is widely distributed among the genomes of photosynthetic bacteria, cyanobacteria and Euglena. Tll0078 protein of thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 has the BLUF domain. The absorption spectrum of this protein showed 10 nm red shift upon the light illumination at room temperature. We studied the photocycle of purified Tll0078 protein expressed in E.coli. The fluorescence decay of the Tll0078 protein showed three exponential decay components with a lifetime of 120 ps (95 %, relative amplitude), 710 ps (4 %) and 4.56 ns (1%). The transient absorption change showed the formation of 10 nm red shifted form at 10 ns after the laser excitation at room temperature. These results indicate the extremely fast primary photoconversion process of BLUF domain at room temperature.
