The primary structure of sensory rhodopsin II: a member of an additional retinal protein subgroup is coexpressed with its transducer, the halobacterial transducer of rhodopsin II.

Abstract

The blue-light receptor genes (sopII) of sensory rhodopsin (SR) II were cloned from two species, the halophilic bacteria Haloarcula vallismortis (vSR-II) and Natronobacterium pharaonis (pSR-II). Upstream of both soplI gene loci, sequences corresponding to the halobacterial transducer of rhodopsin (Htr) II In bacterial taxis, the cell recognizes and reacts actively to numerous chemical and physical stimuli. A well-studied example is found in the chemotactic behavior ofEscherichia coli. The chemoreceptors of E. coli display two functional properties, the reception of the signal on the external side of the cell and the signal transduction to cytoplasmic proteins (reviewed in ref. 1). Characteristic of transducer proteins is their ability to adapt to a constant signal input by reversible methylation of specific sites flanking a cytoplasmic domain (signal domain), which links the incoming signal with cytoplasmic components.In a similar signal transduction system, the phototactic activity of the archaeon Halobacterium salinarium is mediated by photoreceptors (reviewed in refs. 2 and 3) that have a close structural relationship to the ion pumps of bacteriorhodopsin (BR) and halorhodopsin (reviewed in ref. 4). The bacteria are attracted to light >520 nm and repelled by light <500 nm. The photoattractant response of Halobacteria is mediated by sensory rhodopsin (SR) I. In a two-photon reaction, it can also trigger a negative response toward near-UV light. Moreover, repellent light of wavelengths <500 nm is recognized by a second pigment, SR-II, which absorbs at -490 nm.

A Microbial Rhodopsin with a Unique Retinal Composition Shows Both Sensory Rhodopsin II and Bacteriorhodopsin-like Properties

“…S1 and S2). Sensory rhodopsin genes previously identified are followed by the genes of cognate transducers, in an operon that is under control of the same promoter (42). The transducer proteins HtrI for SRI and HtrII for SRII belong to a family of two transmembrane helical proteins similar to chemoreceptors Tar and Tsr in E. coli (31), and they are termed methyl-accepting chemotaxis proteins (31).…”

Shape and oligomerization state of the cytoplasmic domain of the phototaxis transducer II from Natronobacterium pharaonis

“…In SANS, the scattering intensity I(Q) is proportional to the scattering contrast between the protein particle and the solvent ⌬ 2 ϭ ( p Ϫ solvent ) 2 , where p and solvent refer to the scattering length density (SLD) of the particle and the solvent, respectively. For a particle of volume V consisting of atoms with coherent scattering lengths b i the average SLD is defined as…”

“…he photosensory system of the halophilic archaeon Natronobacterium pharaonis consists of sensory rhodopsin II (pSRII) and transducer II (pHtrII) proteins (1,2). Upon absorption of a photon, the seven-transmembrane helical membrane protein pSRII undergoes conformational changes that are transmitted to pHtrII (3).…”

“…Upon absorption of a photon, the seven-transmembrane helical membrane protein pSRII undergoes conformational changes that are transmitted to pHtrII (3). pHtrII is composed of two transmembrane helices and a long intracellular domain that has a CheA͞ CheW kinase-binding site (2). In the light-activated, ''repellent'' state pHtrII enhances the autophosphorylation rate of CheA, which, in turn, phosphorylates CheY.…”

Dynamic structure of pharaonis phoborhodopsin (sensory rhodopsin II) and complex with a cognate truncated transducer as revealed by site‐directed 13C solid‐state NMR

“…In particular, bR and hR are light-driven ion pumps transporting proton and chloride, respectively [1], while the two sensory rhodopsins are photoreceptors active for positive and negative phototaxis, respectively [2]. Here, pharaonis phoborhodopsin (ppR) is a pigment protein from Natronobacterium pharaonis and corresponds to pR of Halobacterium salinarum with 50% homology of amino acid sequence [3,4]. These two photoreceptors with proton transport ability are activated to yield signaling for phototaxis, through their plausible conformational changes, after receiving incoming light by tightly complexed to their respective cognate transducers consisting of two transmembrane helices (TM1 and TM2), Htr I and Htr II, respectively [5].…”