Genomic survey and biochemical analysis of recombinant candidate cyanobacteriochromes reveals enrichment for near UV/Violet sensors in the halotolerant and alkaliphilic cyanobacterium Microcoleus IPPAS B353

摘要: Cyanobacteriochromes (CBCRs), which are exclusive to and widespread among cyanobacteria, photoproteins that sense the entire range of near-UV visible light. CBCRs related red/far-red phytochromes utilize linear tetrapyrrole (bilin) chromophores. Best characterized from unicellular cyanobacterium Synechocystis sp. PCC 6803 multicellular heterocyst forming filamentous cyanobacteria Nostoc punctiforme ATCC 29133 Anabaena 7120, have been poorly investigated in mat-forming, nonheterocystous cyanobacteria. In this study, we sequenced genome one such species, Microcoleus IPPAS B353 (Microcoleus B353), identified two seven with or more bilin-binding cGMP-specific phosphodiesterase, adenylyl cyclase FhlA (GAF) domains. Biochemical spectroscopic measurements 23 purified GAF proteins phycocyanobilin (PCB) producing recombinant Escherichia coli indicated 13 these formed light-absorbing covalent adducts: 10 GAFs contained PCB chromophores, whereas three isomer, phycoviolobilin (PVB). Furthermore, complement is enriched violet sensors, but lacks red/green green/red widely distributed other We hypothesize enrichment short wavelength-absorbing critical for acclimation high-light environments where organism found.