Selenoproteins are proteins containing selenium in the form of the 21st amino acid, selenocysteine (Sec), encoded in the genome with an UAG triplet. Members of this protein family have many diverse functions, but their synthesis is dependent on a common set of cofactors and on dietary selenium. The fact that UAG is at the same time Sec's codeword and a stop codon, has made it difficult to obtain predictions of selenoproteins from a bioinformatic approach.
In the present study we attempted to find the selenoproteins in S. hypoxantha, the tawny-bellied seedeater, a species which selenoproteome has never been studied before, using bioinformatic tools such as tBLASTn, Exonerate, Genewise, T-Coffee and Seblastian through a semi-automized program designed by our group. The same process was done using as query the proteome of a selected evolutionary close species, Gallus gallus, as well as the H. Sapiens for a better and more robust prediction.
After our analysis, we have been able to conclude that Sporophila hypoxantha's genome has the following selenoproteins: GPx1, GPx3, GPx4, the three selenoprotiens of the DIO/DI family, Sel15, SelH, Selenoprotein I, SELENOK(1), SelM, Selenoprotein N, SelO/SELENOO(3), the Selenoprotein P family, Selenoprotein S, Selenoprotein T, Selenoprotein U, TXNRD(2) and two homologs of TXNRD(1)/TR1. As for Cys-containing homologs and machinery, we found the following proteins: eEFsec, GPx7, GPx8, MsrA, PSTK, SBP2(1)/SBP2, SecS(1), SecS(2), SEPHS/SPS1, SELENOO(2), SelR2, MSRB3/SelR3, SelU2, SelW2 and SECp43.
Sporophila hypoxantha