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Evolution of selenoproteins in the metazoan.

Jiang L, Ni J, Liu Q - BMC Genomics (2012)

Bottom Line: Amphioxus was found to have the most abundant and variant selenoproteins of any animal currently characterized, including a special selenoprotein P (SelP) possessing 3 repeated Trx-like domains and Sec residues in the N-terminal and 2 Sec residues in the C-terminal.During evolutionary history, only a few new selenoproteins have emerged and few were lost.Furthermore, the massive loss of selenoproteins in nematodes and insects likely occurred independently in isolated partial evolutionary branches.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Life Sciences, Shenzhen University, Shenzhen, 518060, Guangdong Province, PR, China.

ABSTRACT

Background: The selenocysteine (Sec) containing proteins, selenoproteins, are an important group of proteins present throughout all 3 kingdoms of life. With the rapid progression of selenoprotein research in the post-genomic era, application of bioinformatics methods to the identification of selenoproteins in newly sequenced species has become increasingly important. Although selenoproteins in human and other vertebrates have been investigated, studies of primitive invertebrate selenoproteomes are rarely reported outside of insects and nematodes.

Result: A more integrated view of selenoprotein evolution was constructed using several representative species from different evolutionary eras. Using a SelGenAmic-based selenoprotein identification method, 178 selenoprotein genes were identified in 6 invertebrates: Amphimedon queenslandica, Trichoplax adhaerens, Nematostella vectensis, Lottia gigantean, Capitella teleta, and Branchiostoma floridae. Amphioxus was found to have the most abundant and variant selenoproteins of any animal currently characterized, including a special selenoprotein P (SelP) possessing 3 repeated Trx-like domains and Sec residues in the N-terminal and 2 Sec residues in the C-terminal. This gene structure suggests the existence of two different strategies for extension of Sec numbers in SelP for the preservation and transportation of selenium. In addition, novel eukaryotic AphC-like selenoproteins were identified in sponges.

Conclusion: Comparison of various animal species suggests that even the most primitive animals possess a selenoproteome range and variety similar to humans. During evolutionary history, only a few new selenoproteins have emerged and few were lost. Furthermore, the massive loss of selenoproteins in nematodes and insects likely occurred independently in isolated partial evolutionary branches.

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Multiple alignments of Metazoan SelU proteins. Sec residues are highlighted with a green background.
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Figure 3: Multiple alignments of Metazoan SelU proteins. Sec residues are highlighted with a green background.

Mentions: More than 10 Sec-containing SelU proteins were found in the 6 invertebrates examined in the present study. Among these, only 3 belonged to the SelU1 protein family, and many more belonged to SelU2 or SelU3 families. Multiple alignment and phylogenic analysis showed that all of these 3 SelU family proteins are widespread and highly conserved in vertebrates, including fishes, amphibians, birds, and mammals (seen in Figure 2 and Figure 3). Additionally, the SelU proteins of invertebrates diverged into 3 groups, classified into different families in accordance with the proteins of their vertebrate descendants. The Sec residues in these proteins were often changed into Cys residues in different stages of these 3 lineages, as shown in the phylogenic tree in Figure 2. In the SelU2 lineage, only one Sec-containing member was found in the primitive invertebrate Trichoplax adhaerens, suggesting that Sec to Cys events likely occurred in the early era of invertebrates. The SelU3 lineage represented the most abundant group of invertebrate SelU proteins identified, as 8 SelU3 proteins were found in the 7 species that constituted this group. Interestingly, of these 8 SelU3 proteins, 3 were in Cys form and belonged to more advanced invertebrates, such as sea urchin, amphioxus, and sea squirt. This suggests a clear timeframe during which Sec changed into Cys in the evolution of the SelU3 family. All Cys forms of SelU3 belonged to the deuterostome phylum. Thus, the Sec to Cys change event may have occurred before the divergence of this phylum.


Evolution of selenoproteins in the metazoan.

Jiang L, Ni J, Liu Q - BMC Genomics (2012)

Multiple alignments of Metazoan SelU proteins. Sec residues are highlighted with a green background.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3473315&req=5

Figure 3: Multiple alignments of Metazoan SelU proteins. Sec residues are highlighted with a green background.
Mentions: More than 10 Sec-containing SelU proteins were found in the 6 invertebrates examined in the present study. Among these, only 3 belonged to the SelU1 protein family, and many more belonged to SelU2 or SelU3 families. Multiple alignment and phylogenic analysis showed that all of these 3 SelU family proteins are widespread and highly conserved in vertebrates, including fishes, amphibians, birds, and mammals (seen in Figure 2 and Figure 3). Additionally, the SelU proteins of invertebrates diverged into 3 groups, classified into different families in accordance with the proteins of their vertebrate descendants. The Sec residues in these proteins were often changed into Cys residues in different stages of these 3 lineages, as shown in the phylogenic tree in Figure 2. In the SelU2 lineage, only one Sec-containing member was found in the primitive invertebrate Trichoplax adhaerens, suggesting that Sec to Cys events likely occurred in the early era of invertebrates. The SelU3 lineage represented the most abundant group of invertebrate SelU proteins identified, as 8 SelU3 proteins were found in the 7 species that constituted this group. Interestingly, of these 8 SelU3 proteins, 3 were in Cys form and belonged to more advanced invertebrates, such as sea urchin, amphioxus, and sea squirt. This suggests a clear timeframe during which Sec changed into Cys in the evolution of the SelU3 family. All Cys forms of SelU3 belonged to the deuterostome phylum. Thus, the Sec to Cys change event may have occurred before the divergence of this phylum.

Bottom Line: Amphioxus was found to have the most abundant and variant selenoproteins of any animal currently characterized, including a special selenoprotein P (SelP) possessing 3 repeated Trx-like domains and Sec residues in the N-terminal and 2 Sec residues in the C-terminal.During evolutionary history, only a few new selenoproteins have emerged and few were lost.Furthermore, the massive loss of selenoproteins in nematodes and insects likely occurred independently in isolated partial evolutionary branches.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Life Sciences, Shenzhen University, Shenzhen, 518060, Guangdong Province, PR, China.

ABSTRACT

Background: The selenocysteine (Sec) containing proteins, selenoproteins, are an important group of proteins present throughout all 3 kingdoms of life. With the rapid progression of selenoprotein research in the post-genomic era, application of bioinformatics methods to the identification of selenoproteins in newly sequenced species has become increasingly important. Although selenoproteins in human and other vertebrates have been investigated, studies of primitive invertebrate selenoproteomes are rarely reported outside of insects and nematodes.

Result: A more integrated view of selenoprotein evolution was constructed using several representative species from different evolutionary eras. Using a SelGenAmic-based selenoprotein identification method, 178 selenoprotein genes were identified in 6 invertebrates: Amphimedon queenslandica, Trichoplax adhaerens, Nematostella vectensis, Lottia gigantean, Capitella teleta, and Branchiostoma floridae. Amphioxus was found to have the most abundant and variant selenoproteins of any animal currently characterized, including a special selenoprotein P (SelP) possessing 3 repeated Trx-like domains and Sec residues in the N-terminal and 2 Sec residues in the C-terminal. This gene structure suggests the existence of two different strategies for extension of Sec numbers in SelP for the preservation and transportation of selenium. In addition, novel eukaryotic AphC-like selenoproteins were identified in sponges.

Conclusion: Comparison of various animal species suggests that even the most primitive animals possess a selenoproteome range and variety similar to humans. During evolutionary history, only a few new selenoproteins have emerged and few were lost. Furthermore, the massive loss of selenoproteins in nematodes and insects likely occurred independently in isolated partial evolutionary branches.

Show MeSH
Related in: MedlinePlus