Identification and Functional Analysis of Photoreceptors in Blakeslea trispora.

In this study, we isolated and characterized three photoreceptor genes, btwc-1a, btwc-1b and btwc-1c in B. trispora Bioinformatics analyses of these genes and their protein sequences revealed that their functional domains (PAS/LOV domain and zinc finger structure) have significant homology to other fungal blue-light regulator proteins from Mucor circinelloides and Neurospora crassa The photoreceptor proteins were synthesized by heterologous expression in Escherichia coli The chromogenic groups FAD and FMN were detected to accompany BTWC-1 proteins by using high performance liquid chromatography (HPLC) and fluorescence spectrometry, demonstrating that the proteins may be photosensitive. The absorbance change of the purified BTWC-1 proteins in dark and light indicated that they were light responsive and underwent a characteristic photocycle by light induction. Site-directed mutagenesis of the cysteine residual (Cys) in BTWC-1 did not affect the normal expression of the protein in E. coli, but led to the loss of photocycle response, indicating that Cys is flavin-binding domain for photon detection. We then analyzed the functions of BTWC-1 proteins by complementing btwc-1a, btwc-1b and btwc-1c into their counterpart knockout strains of M. circinelloides for each mcwc-1 gene. Transformation of the btwc-1a-complement into mcwc-1a knockout strains restored the positive phototropism, while the addition of btwc-1c-complement remedied the deficiency of carotene biosynthesis in the mcwc...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research