The primary structure of mantid opsin

Area of Science:

• Molecular Biology
• Biochemistry
• Evolutionary Biology

Background:

• Opsins are crucial proteins in visual pigments, responsible for light detection.
• Insect opsins typically bind 3-hydroxy retinal, but variations exist across species.
• Understanding opsin diversity provides insights into visual system evolution.

Purpose of the Study:

• To determine the sequence and structural characteristics of opsin from the mantid Sphodromantis sp.
• To compare mantid opsin with known insect opsins to identify evolutionary relationships.
• To investigate the cofactor binding preference of mantid rhodopsin.

Main Methods:

• Dideoxynucleotide sequencing of PCR products from mantid eye cup cDNA.
• Bioinformatic analysis of amino acid sequence and predicted protein structure (hydropathy profile).
• Comparative analysis of transmembrane sequences within the opsin family.

Main Results:

• The Sphodromantis sp. opsin sequence was determined, encoding a 376-amino-acid protein.
• The protein exhibits a seven-transmembrane structure characteristic of rhodopsins.
• Mantid opsin shows significant identity (56%) and similarity (85%) to Drosophila and Calliphora opsins.
• Crucially, mantid rhodopsin binds 11-cis retinal, differing from the 3-hydroxy retinal found in other characterized insect visual pigments.

Conclusions:

• Mantid opsin represents a distinct evolutionary lineage within insect visual pigments.
• The binding of 11-cis retinal in mantids suggests an alternative biochemical pathway for vision.
• Further research into specific amino acid substitutions may elucidate the mechanism for cofactor selection in insect opsins.