Title |
Neofunctionalization of a duplicate hatching enzyme gene during the evolution of teleost fishes
|
---|---|
Published in |
BMC Ecology and Evolution, October 2014
|
DOI | 10.1186/s12862-014-0221-0 |
Pubmed ID | |
Authors |
Kaori Sano, Mari Kawaguchi, Satoshi Watanabe, Shigeki Yasumasu |
Abstract |
BackgroundDuplication and subsequent neofunctionalization of the teleostean hatching enzyme gene occurred in the common ancestor of Euteleostei and Otocephala, producing two genes belonging to different phylogenetic clades (clades I and II). In euteleosts, the clade I enzyme inherited the activity of the ancestral enzyme of swelling the egg envelope by cleavage of the N-terminal region of egg envelope proteins. The clade II enzyme gained two specific cleavage sites, N-ZPd and mid-ZPd but lost the ancestral activity. Thus, euteleostean clade II enzymes assumed a new function; solubilization of the egg envelope by the cooperative action with clade I enzyme. However, in Otocephala, the clade II gene was lost during evolution. Consequently, in a late group of Otocephala, only the clade I enzyme is present to swell the egg envelope. We evaluated the egg envelope digestion properties of clade I and II enzymes in Gonorynchiformes, an early diverging group of Otocephala, using milkfish, and compared their digestion with those of other fishes. Finally, we propose a hypothesis the neofunctionalization process.ResultsThe milkfish clade II enzyme cleaved N-ZPd but not mid-ZPd, and did not cause solubilization of the egg envelope. We conclude that neofunctionalization is incomplete in the otocephalan clade II enzymes. Comparison of clade I and clade II enzyme characteristics implies that the specificity of the clade II enzymes gradually changed during evolution after the duplication event, and that a change in substrate was required for the addition of the mid-ZPd site and loss of activity at the N-terminal region.ConclusionsWe infer the process of neofunctionalization of the clade II enzyme after duplication of the gene. The ancestral clade II gene gained N-ZPd cleavage activity in the common ancestral lineage of the Euteleostei and Otocephala. Subsequently, acquisition of cleavage activity at the mid-ZPd site and loss of cleavage activity in the N-terminal region occurred during the evolution of Euteleostei, but not of Otocephala. The clade II enzyme provides an example of the development of a neofunctional gene for which the substrate, the egg envelope protein, has adapted to a gradual change in the specificity of the corresponding enzyme. |
Mendeley readers
Geographical breakdown
Country | Count | As % |
---|---|---|
Unknown | 29 | 100% |
Demographic breakdown
Readers by professional status | Count | As % |
---|---|---|
Student > Bachelor | 6 | 21% |
Student > Ph. D. Student | 3 | 10% |
Researcher | 3 | 10% |
Professor | 2 | 7% |
Student > Doctoral Student | 2 | 7% |
Other | 8 | 28% |
Unknown | 5 | 17% |
Readers by discipline | Count | As % |
---|---|---|
Agricultural and Biological Sciences | 16 | 55% |
Biochemistry, Genetics and Molecular Biology | 5 | 17% |
Environmental Science | 1 | 3% |
Unspecified | 1 | 3% |
Chemistry | 1 | 3% |
Other | 0 | 0% |
Unknown | 5 | 17% |