# Heterodisulfide

By [Esaydodo](https://paragraph.com/@esaydodo) · 2021-10-28

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Heterodisulfide reductase subunit A (HdrA) was the second most abundant selenoprotein family, which was represented by 10 selenoprotein genes. It is interesting that most of the HdrA sequences were found to cluster with FrhD sequences. This finding is consistent with our previous hypothesis that the _hdrA-frhD-frhG-frhA_ cluster could be laterally transferred between Sec-decoding archaea and _Deltaproteobacteria_ . A rhodanese-related sulfurtransferase \[8 genes, \], AhpD-like (7 genes), Prx-like thiol:disulfide oxidoreductase (6 genes) and proline reductase (PR, 5 genes) were the next most abundant selenoprotein families. These six families accounted for 58.5% of known selenoprotein sequences, suggesting importance of their functions in the symbiosis involving _Deltaproteobacteria_ and the host worm. Other detected selenoprotein families included formate dehydrogenase alpha subunit (FdhA), F420-reducing hydrogenase alpha subunit (FrhA), selenophosphate synthetase (SelD), HesB-like, Fe-S oxidoreductase (GlpC), methionine sulfoxide reductase A (MsrA) and several other selenoprotein families.

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*Originally published on [Esaydodo](https://paragraph.com/@esaydodo/heterodisulfide)*