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Updated: Feb 25, 2026
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Published on: March 1, 2012
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Symplectin evolved from multiple duplications in bioluminescent squid.
Warren R Francis1,2, Lynne M Christianson1, Steven H D Haddock1
1Monterey Bay Aquarium Research Institute, Moss Landing, CA, United States of America.
Peerj
|August 9, 2017
Summary
Bioluminescent squid use a unique enzyme, symplectin, for light production. This study reveals symplectin belongs to a larger protein family with conserved functional sites, suggesting multiple roles beyond bioluminescence.
Area of Science:
- Marine Biology
- Biochemistry
- Evolutionary Biology
Background:
- Bioluminescence in cephalopods, particularly squid like Sthenoteuthis oualaniensis, relies on the luciferin coelenterazine and a specific enzyme, symplectin.
- Limited genetic data exists for bioluminescent cephalopods, with proteins like symplectin often appearing as isolated sequences in databases.
Purpose of the Study:
- To investigate the distribution and evolutionary history of the symplectin/pantetheinase protein family in Metazoa.
- To analyze the occurrence of this protein family in cephalopods, including four newly sequenced luminous squid species.
Main Methods:
- Transcriptome sequencing of four additional luminous squid species.
- Analysis of publicly available cephalopod genomic data.
- Comparative analysis of the symplectin/pantetheinase protein family across Metazoa.
Main Results:
- Four distinct protein groups within the symplectin/pantetheinase family were identified in cephalopods, with one group corresponding to symplectin.
- A critical cysteine residue essential for symplectin function is conserved across most family members.
- Active site residues for pantetheinase catalysis are also conserved, indicating potential dual functions for symplectin.
Conclusions:
- Symplectin likely possesses hydrolase activity in addition to its role in bioluminescence.
- The evolution of bioluminescence in squid involved modifications to symplectin beyond its primary binding pocket.
- The symplectin/pantetheinase protein family exhibits a broader distribution and evolutionary history than previously understood.
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