Phylogenetic Analysis of Canonical/non-canonical Dicers and RNase III Containing Proteins in Fungal Kingdom

Background: Dicers were member of RNase III containing proteins family with important RNAi function in eukaryotes. In this study, we tried to address the potential distribution of all RNase III containing proteins among the fungal kingdom, as well as their possible evolution paths including canonical Dicers, non-canonical Dicers and non-canonical Dicer-like proteins.Result: RNase III containing proteins were collected from 83 species, and discussed the features and possible evolution pathways of RNase III containing protein family. In general, RNase III containing protein family could be characterized into three different groups as canonical Dicer, non-canonical Dicers and Dicer-like proteins based on their domain structures and functional annotation. Most eukaryotes obtained multiple RNase III protein of different types at the same time, including canonical Dicers and Dicer-like proteins. Phylogenetic analysis showed that the RNase III domains were different between canonical Dicers and Dicer-like proteins, for the first and second RNase III domains had different insertions in different regions with certain extent of conservation. Regardless of the types, RNA-binging domains in RNase III protein family were very similar to each other. Furthermore, short insertions were found in different positions from the first and second RNase III domains in canonical Dicers separately. RNA-binging domains from all types were quite similar to each other.Conclusion: RNase III containing proteins in general widely exist in eukaryotes with minor divergent among different types and groups. Suggested by the RNase III and RDB domains, the canonical/non-canonical Dicers Dicer-like proteins might share the same ancestor and have evolved from separate mild-types through different directions.