Structural modeling of marine mammal melanopsin (Opn4) spectral tuning amino acid positions.

• Main Authors: Jeffry I. Fasick (3624569), Haya Algrain (11570761), Courtland Samuels (11570764), Padmanabhan Mahadevan (475388), Lorian E. Schweikert (3624572), Zaid J. Naffaa (11570767), Phyllis R. Robinson (204369)
• Format: Still Image
• Language: unknown
• Published: 2021
• Subjects: Biochemistry; Cell Biology; Molecular Biology; Neuroscience; Evolutionary Biology; Ecology; Virology; Environmental Sciences not elsewhere classified; water &# 8217; serve light detection; retinal ganglion cells; carboxyl terminal domain; available light spectra; marine mammal rhodopsins; thus longer mydriasis; extended pupillary constriction; amino acid substitutions; marine mammal species; div >< p; marine mammals may; marine mammals; pupil constriction; mydriasis occurs; identify substitutions; given species; values tuned; values relative; terrestrial counterparts; terrestrial controls; spectral tuning; spectral sensitivity; solar irradiance; significant change; rod retina; rod monochromacy; results suggest; results show; previous work; prevent photobleaching; orders sirenia; likely involved; infraorder cetacea; highly photosensitive; foraging depths; deactivation kinetics; condition known; cdna sequences; absorbance maxima; Weddell; Weddell Seal; walrus*
• Online Access: https://doi.org/10.1371/journal.pone.0257436.g004

3-D images of marine mammal Opn4 proteins (teal) were aligned with squid Rh1 (green) to determine relative positions of helices and residues. (A) squid rhodopsin (Protein Data Bank accession number 2Z73) showing the relative position of the ten nonconservative amino acid substitutions from Fig 3 . A proposed protonated Schiff base counterion (Glu214) [ 77 – 79 ] is shown in orange. Panels B-D highlight nonconservative amino acids potentially involved in spectral tuning and their relative predicted distance to the retinal Schiff base lysine (red) terminal NZ atom or the β-ionone ring of the chromophore (yellow): (B) manatee Thr123 (9.5 Å); (C) Yangtze river dolphin Thr128 (11.8 Å); and (D) Weddell seal Ala311 (9.3 Å); Weddell seal and walrus Thr315 (11.2 Å). Opn4 numbering is from mouse.