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A trypsin homolog in amphioxus: expression, enzymatic activity and evolution
1Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Room 205, Ke Xue Guan, 5 Yushan Road, Qingdao 266003, China.
Molecular Biology Reports
|June 1, 2011
Summary
Researchers identified a trypsin gene in amphioxus (Branchiostoma japonicum), a key organism for understanding vertebrate evolution. This study details its gene expression and evolutionary relationships, offering insights into digestive enzyme origins.
Area of Science:
- * Evolutionary Biology
- * Molecular Biology
- * Genomics
Background:
- * Trypsin, a digestive enzyme, is found across diverse species, but its role in amphioxus, crucial for vertebrate evolutionary studies, remains largely uncharacterized.
- * Understanding amphioxus trypsin provides insights into the evolution of digestive systems and vertebrate origins.
Purpose of the Study:
- * To identify and characterize a trypsin gene in the amphioxus species Branchiostoma japonicum.
- * To investigate the functional properties and expression patterns of amphioxus trypsin.
- * To explore the evolutionary position of amphioxus trypsin relative to other species.
Main Methods:
- * Molecular cloning and sequencing of the amphioxus trypsin gene.
- * Expression and purification of recombinant amphioxus trypsin protein.
- * Enzymatic activity assays using a prototypic substrate and specific inhibitor.
- * Gene expression analysis using Northern blotting and in situ hybridization (tissue section and whole mount).
- * Phylogenetic analysis of trypsin sequences.
Main Results:
- * A trypsin gene was identified in Branchiostoma japonicum, encoding a protein with characteristic trypsinogen features.
- * Recombinant amphioxus trypsin exhibited enzymatic activity, hydrolyzing BAEE substrate and being inhibited by soybean trypsin inhibitor.
- * The trypsin gene displayed tissue-specific expression, predominantly in the hepatic caecum, mid-gut, and ovary.
- * Expression was observed early in larval development in the primitive gut, preceding hepatic caecum formation.
- * Phylogenetic analysis revealed that amphioxus and ascidian trypsins are more closely related to each other than to vertebrate trypsins.
Conclusions:
- * The identified amphioxus trypsin possesses functional characteristics similar to other known trypsins.
- * Tissue-specific expression suggests a significant role in digestion and reproduction in amphioxus.
- * Evolutionary analysis indicates that vertebrate trypsins diverged after the split from the protochordate/vertebrate common ancestor.
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