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.
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 sopII gene loci, sequences corresponding to the halobacterial transducer of rhodopsin (Htr) II were recognized. In N. pharaonis, psopII and phtrII are transcribed as a single transcript. Comparison of the amino acid sequences of vHtr-II and pHtr-II with Htr-I and the chemotactic methyl-accepting proteins from Escherichia coli revealed considerable identities in the signal domain and methyl-accepting sites. Similarities with Htr-I in Halobacterium salinarium suggest a common principle in the phototaxis of extreme halophiles. Alignment of all known retinal protein sequences from Archaea identifies both SR-IIs as an additional subgroup of the family. Positions defining the retinal binding site are usually identical with the exception of Met-118 (numbering is according to the bacteriorhodopsin sequence), which might explain the typical blue color shift of SR-II to approximately 490 nm. In archaeal retinal proteins, the function can be deduced from amino acids in positions 85 and 96. Proton pumps are characterized by Asp-85 and Asp-96; chloride pumps by Thr-85 and Ala-96; and sensors by Asp-85 and Tyr-96 or Phe-96.
Seidel
R
R
Max-Planck-Institut für Molekulare Physiologie, Dortmund, Germany.
Scharf
B
B
Gautel
M
M
Kleine
K
K
Oesterhelt
D
D
Engelhard
M
M
D000595:Amino Acid Sequence; D001105:Archaea / Q000378:metabolism*; D019843:Archaeal Proteins; D001436:Bacteriorhodopsins / Q000096:biosynthesis* / Q000737:chemistry*; D001483:Base Sequence; D015139:Blotting, Southern; D002338:Carotenoids; D003001:Cloning, Molecular; D017931:DNA Primers; D004269:DNA, Bacterial / Q000302:isolation & purification; D005798:Genes, Bacterial; D015698:Genomic Library; D016931:Halobacteriales / Q000378:metabolism*; D006217:Halobacterium / Q000378:metabolism; D025602:Halorhodopsins; D008969:Molecular Sequence Data; D018524:Phototropism; D016133:Polymerase Chain Reaction; D025603:Sensory Rhodopsins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D019843:Archaeal Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D025602:Halorhodopsins; D025603:Sensory Rhodopsins; C061508:sensory rhodopsin II protein, archaeal; D002338:Carotenoids; D001436:Bacteriorhodopsins