Characterization of Cyanobacteriochrome TePixJ from a Thermophilic Cyanobacterium Thermosynechococcus elongatus Strain BP-1

Abstract

A putative photoreceptor gene, TepixJ, of a thermophilic cyanobacterium is homologous to SypixJ1 that mediates positive phototaxis in the unicellular motile cyanobacterium Synechocystis sp. PCC 6803. The putative chromophore-binding GAF domain of TePixJ protein was overexpressed as a fusion with a polyhistidine tag (His-TePixJ_GAF) in Synechocystis cells and isolated to homogeneity. The photoreversible conversion of His-TePixJ_GAF showed peaks at 531, 341 and 266 nm for the green light-absorbing form (Pg form), and peaks at 433 and 287 nm for the blue light-absorbing form (Pb form). At 77K, the Pg form fluoresced at 580 nm, while the Pb form did not emit any fluorescence. Mass spectrometry of the tryptic chromopeptide demonstrated that a phycocyanobilin isomer binds to the conserved cysteine at ring A via a thioether bond. It is established that TePixJ and SyPixJ1 are novel photoreceptors in cyanobacteria ('cyanobacteriochromes') that are similar, but distinct from the phytochromes and bacteriophytochromes.

Green/red cyanobacteriochromes regulate complementary chromatic acclimation via a protochromic photocycle

“…The PCR products were cloned individually into pPCR-Script (Agilent) and confirmed by DNA sequencing. The constructs then were excised by NdeI and BamHI digestion and subcloned into the N-terminally hexahistidine-tagged vectors pET28a (Merck) and pTCH2031v (15) for expression in E. coli or in Synechocystis cells, respectively. Site-directed mutagenesis was performed according to the manufacturer's instructions using QuikChange kit reagents (Agilent) and the primer sets shown in Table S1.…”

“…* Cyanobacteriochromes (CBCRs) are widespread cyanobacterial photosensors with phytochrome-related GAF domains (1,2,13,14). Although CBCRs also convert between two photostates via bilin photoisomerization at C15, they exhibit much more spectral diversity, with peak absorptions ranging from 330 to 680 nm and hence spanning the entire visible spectrum and near UV (13,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24). CBCR subfamilies that sense light in the near-UV to blue region (330-470 nm) have been studied extensively.…”

Shedding new light on the regulation of complementary chromatic adaptation

“…TePixJ, a phytochrome-like protein found in the cyanobacterium Thermosynechococcus elongatus, purportedly bears linear tetrapyrrole phycoviolobilin (PVB) as its chromophore in vivo [7]. TePixJ was the first member of a family of related proteins to be characterized as a sensory photoreceptor that responds to blue light (BL) and GL [8]. TePixJ is a homologue of a protein that was shown to function as a photoreceptor involved in the regulation of phototaxis through a CheA/CheY-type signaling pathway in the cyanobacterium Synechocystis sp.…”

“…Most recently reviewed in 2006 by Kehoe and Gutu [3], a number of seminal insights have been made regarding the regulation of CCA during the past few years. These advances include progress in our understanding of the mechanisms utilized by transcriptional regulators that control CCA responses [4,5], and the identification of novel roles for sensory photoreceptors involved in the regulation of distinct aspects of the CCA process [6], in addition to other related novel developments [7][8][9][10][11][12]. The photoregulation of pigmentation -i.e.…”

Construction of a photo-responsive chimeric histidine kinase in <i>Escherichia coli</i>

“…Cyanobacteria have evolved a diverse set of photo-sensing proteins, cyanobacteriochromes, such as AnPixJ of Anabaena sp. PCC7120 (Fukushima et al, 2011), SyPixJ (Yoshihara et al, 2000), SyPixD (Okajima et al, 2005), TePixJ (Ishizuka et al, 2006), and CcaS proteins of Synechocystis sp. PCC 6803 and Nostoc punctiforme (Hirose et al, 2008(Hirose et al, , 2010.…”