A novel spectral tuning in the short wavelength-sensitive (SWS1 and SWS2) pigments of bluefin killifish (Lucania goodei)

Gene. 2007 Jul 1;396(1):196-202. doi: 10.1016/j.gene.2007.03.019. Epub 2007 Apr 14.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Fish Proteins / chemistry*
  • Killifishes / metabolism*
  • Phylogeny
  • Retinal Pigments / chemistry*
  • Spectrophotometry

Substances

  • Fish Proteins
  • Retinal Pigments