A novel spectral tuning in the short wavelength-sensitive (SWS1 and SWS2) pigments of bluefin killifish (Lucania goodei).
The molecular bases of spectral tuning in the UV-, violet-, and blue-sensitive pigments are not well understood. Using the in vitro assay, here we show that the SWS1, SWS2-A, and SWS2-B pigments of bluefin killifish (Lucania goodei) have the wavelengths of maximal absorption (lambda(max)'s) of 354, 448, and 397 nm, respectively. The spectral difference between the SWS2-A and SWS2-B pigments is largest among those of all currently known pairs of SWS2 pigments within a species. The SWS1 pigment contains no amino acid replacement at the currently known 25 critical sites and seems to have inherited its UV-sensitivity directly from the vertebrate ancestor. Mutagenesis analyses show that the amino acid differences at sites 44, 46, 94, 97, 109, 116, 118, 265, and 292 of the SWS2-A and SWS2-B pigments explain 80% of their spectral difference. Moreover, the larger the individual effects of amino acid changes on the lambda(max)-shift are, the larger the synergistic effects tend to be generated, revealing a novel mechanism of spectral tuning of visual pigments.
Yokoyama
Shozo
S
Department of Biology, Rollins Research Center, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA. syokoya@emory.edu
Takenaka
Naomi
N
Blow
Nathan
N
D019943:Amino Acid Substitution; D000818:Animals; D029941:Fish Proteins / Q000737:chemistry*; D007695:Killifishes / Q000378:metabolism*; D010802:Phylogeny; D012168:Retinal Pigments / Q000737:chemistry*; D013053:Spectrophotometry
D029941:Fish Proteins; D012168:Retinal Pigments